ACUS48 KWNS 010821
SWOD48
SPC AC 010819

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0319 AM CDT Tue Oct 01 2024

Valid 041200Z - 091200Z

...DISCUSSION...
Recent model guidance has come into better agreement with regard to
the upper-level pattern this weekend into early next week. As zonal
flow begins to break down this Friday, an upper-level trough will
dig southeastward and strengthen. Though conditional and uncertain,
some severe threat could develop in association with this trough.
After this trough exits the East Coast, ridging aloft and at the
surface is expected to develop in its wake.

On Saturday, a cold front will move through the Upper Midwest. Some
moisture return is possible on the western flank of the surface
ridge, but the quality of this moisture is highly uncertain. Wind
fields would support organized storms in parts of the upper
Mississippi Valley, but predictability remains quite low.

For Sunday, the upper-level trough will continue southeastward with
some intensification expected, especially towards Monday morning. A
similar setup to Saturday will occur in parts of the upper Ohio
Valley region. The strongest shear will likely be post-frontal, but
some stronger storms could develop along the front during the
afternoon. Moisture return ahead of the boundary remains a question
and will be the key to severe potential.

A strong mid-level jet will dig into the Mid-Atlantic Monday
morning. Given the misaligned timing of the trough with diurnal
heating, it is not clear that sufficient buoyancy will be present
for an organized severe threat.

..Wendt.. 10/01/2024

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ACUS48 KWNS 020833
SWOD48
SPC AC 020832

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0332 AM CDT Wed Oct 02 2024

Valid 051200Z - 101200Z

...DISCUSSION...
A strong upper trough will move through the Northern Plains and into
the upper Great Lakes region on Saturday. An attendant cold front
will move eastward along with the trough. This system will then move
into the lower Great Lakes/Ohio Valley on Sunday before digging
southeastward into the Mid-Atlantic on Monday. Thereafter, models
forecast upper ridging to build in across much of the CONUS by the
middle of next week, broadly reducing severe weather potential in
the process.

...Upper Mississippi Valley...
Forcing from the upper-level trough will be strong on Saturday.
Storms could develop along the cold front and wind shear would be
sufficient for organized storms. Uncertainty remains rather high as
the quality of moisture return along the western flank of the
anticyclone to the east will be key to overall magnitude of severe
potential, should any materialize.

...Upper Ohio Valley...
As the upper trough and cold front continue eastward, some
destabilization could occur ahead of the front on Sunday afternoon.
As with Saturday, moisture quality ahead of the front remains a
major question. Severe potential remains uncertain.

..Wendt.. 10/02/2024

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ACUS48 KWNS 030841
SWOD48
SPC AC 030839

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0339 AM CDT Thu Oct 03 2024

Valid 061200Z - 111200Z

...DISCUSSION...
A strong upper trough will broaden across the Upper Midwest into
parts of the Northeast on Sunday. An associated cold front will move
through the upper Ohio Valley on Sunday and off the Mid-Atlantic
Coast early to mid morning on Monday. Thereafter, broad troughing
will remain in the Northeast until late in the week as an expansive
upper ridge envelops much of the CONUS.

...Upper-Ohio Valley Vicinity...
The cold front will continue eastward on Sunday, moving through Ohio
during the mid/late afternoon. Moisture return ahead of the front
will be the main source of uncertainty in terms of how much severe
threat there could be. Mid-level forcing will be sufficient, but
low-level veering ahead of the front suggests uncertain storm
coverage. A conditional threat for damaging winds exists during the
late afternoon.

..Wendt.. 10/03/2024

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ACUS48 KWNS 040836
SWOD48
SPC AC 040834

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0334 AM CDT Fri Oct 04 2024

Valid 071200Z - 121200Z

...DISCUSSION...
Medium-range guidance continues to show cyclonic flow aloft
persisting over the northeast CONUS from D4/Monday into D6/Wednesday
before extensive upper ridging over the western and central CONUS
builds eastward and displaces the cyclone. Even with this cyclonic
flow persisting early next week, much of the low-level moisture will
likely be off the Northeast coast by early D4/Monday. Modest
low-level moisture will likely linger across much of the Southeast
and Gulf Coast for much of the week, with some thunderstorm threat
persisting, predominately across the FL Peninsula.

Dry and stable conditions are currently expected elsewhere across
the CONUS as upper ridging builds eastward and the continental
airmass remains in place.

..Mosier.. 10/04/2024

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ACUS48 KWNS 050845
SWOD48
SPC AC 050843

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0343 AM CDT Sat Oct 05 2024

Valid 081200Z - 131200Z

...DISCUSSION...
A mature mid-latitude cyclone is forecast to gradually shift
eastward across southern Quebec on D4/Tuesday and D5/Wednesday as a
series of shortwave troughs rotate through the enhanced mid-level
flow throughout its base. At the same time, expansive upper ridging
will build eastward. By early D6/Thursday, this ridging is expected
to extend from the Southwest northward across the Plains and Upper
MS Valley into Ontario. Further eastward progression/expansion of
this ridging is anticipated on D7/Friday, although some dampening is
possible along its northern periphery over the Canadian Prairies.
This pattern evolution will maintain a stable airmass across the
majority of the CONUS.

The only exception is across FL, where a tropical airmass will
remain in place throughout the period. Additionally, medium-range
guidance continues to suggest tropical cyclone development could
occur over the Gulf of Mexico, with potential impacts across the FL
Peninsula on D4/Tuesday and D5/Wednesday.

..Mosier.. 10/05/2024

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ACUS48 KWNS 060835
SWOD48
SPC AC 060833

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0333 AM CDT Sun Oct 06 2024

Valid 091200Z - 141200Z

...DISCUSSION...
The National Hurricane Center is forecasting Tropical Cyclone Milton
to move across the Florida Peninsula on Wednesday/Day 4. A tornado
threat, associated with Milton, will likely affect parts of the
Florida Peninsula throughout much of the day, and possibly into the
night period. The magnitude of Milton as it crosses the Florida
Peninsula, and any associated severe threat, is highly uncertain at
this time. It seems probable that Milton will be in the western
Atlantic by Thursday morning, which would push the tornado threat
away from the Florida Peninsula. From Friday to Sunday, a
quasi-stationary front is forecast to remain in the vicinity of the
Gulf Coast, with the moist airmass to the south of the front
forecast to remain mostly offshore across the Gulf of Mexico.
Although some thunderstorms could occur over parts of the Florida
Peninsula from Thursday to Sunday, instability is forecast to be too
week for a severe threat.

..Broyles.. 10/06/2024

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ACUS48 KWNS 070832
SWOD48
SPC AC 070830

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0330 AM CDT Mon Oct 07 2024

Valid 101200Z - 151200Z

...DISCUSSION...
Current forecast track from the National Hurricane Center places
Hurricane Milton just off the east-central FL Coast early
D4/Thursday morning. This system is expected to interact with a
larger scale upper trough moving across the eastern CONUS throughout
the day on D4/Thursday, causing it to eject quickly northeastward
into the Atlantic. Upper ridging will likely be in place from the
Southwest into the Upper Great Lakes on D4/Thursday, and this
ridging is expected to shift eastward in the wake of the eastern
CONUS troughing. Some dampening of this ridge is possible on
D4/Thursday and D5/Friday as a shortwave trough progresses
throughout its northern periphery across central Canada and
Ontario/Upper Great Lakes. The northern stream is expected to stay
fairly active during the weekend, with another shortwave trough
likely dropping from the Canadian Prairies and Great Lakes on
D7/Sunday.

Any stronger mid-level flow will be displaced north of the better
low-level moisture on D4/Thursday and D5/Friday. Some moisture
return into the Mid MS and OH Valleys is possible on D6/Saturday and
D7/Sunday, ahead of a potential cold front that is currently
expected to move through on D7/Sunday. Current guidance suggest the
moisture return will be limited, tempering the overall buoyancy and
keeping the severe potential low.

..Mosier.. 10/07/2024

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ACUS48 KWNS 080818
SWOD48
SPC AC 080816

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0316 AM CDT Tue Oct 08 2024

Valid 111200Z - 161200Z

...DISCUSSION...
A pair of fast-moving, low-amplitude shortwave troughs are expected
to progress through the enhanced westerly flow over southern Canada
throughout the period. The first shortwave is forecast to move from
Ontario through the St. Lawrence Valley and New England on
D4/Friday. The second shortwave will follow quickly in the wake of
the first, progressing from the Canadian Prairies through the Upper
Midwest and Upper Great Lakes on D5/Saturday. Beginning late
D5/Saturday or early D6/Sunday, this second shortwave may further
mature into a cyclone over eastern Ontario. This cyclone is then
forecast to drift eastward early next week, with upper troughing
associated with this system expanding over the central and eastern
CONUS.

Some modest moisture return is possible into the Mid MS and OH
Valleys on D5/Saturday and D6/Sunday, ahead of a potential cold
front that is currently expected to move through on D6/Sunday.
Current guidance suggest the moisture return, and associated
buoyancy, will be limited, tempering the overall buoyancy and
keeping the severe potential low. A dry continental airmass will
build in behind the front, promoting stable conditions the majority
of the central and eastern CONUS early next week.

..Mosier.. 10/08/2024

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ACUS48 KWNS 090832
SWOD48
SPC AC 090830

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0330 AM CDT Wed Oct 09 2024

Valid 121200Z - 171200Z

...DISCUSSION...
Overall upper pattern across the central and eastern CONUS is
expected to undergo significant amplification from D4/Saturday into
D7/Tuesday as a series of shortwave troughs move through
progressively deeper troughing. By early D7/Tuesday, upper troughing
is expected to extend from the primary cyclone over the Canadian
Maritimes into the central Plains.

A cold front is expected to accompany the first shortwave trough,
moving across the eastern CONUS on D4/Saturday and D5/Sunday.
Limited buoyancy should keep the thunderstorm potential along this
front low. Strong ridging will follow in the wake of this front,
with dry and stable conditions precluding thunderstorms across the
majority of the CONUS. The only exception is along the Gulf
Coast/Florida, where enough low-level moisture may be in place to
support some thunderstorms.

..Mosier.. 10/09/2024

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ACUS48 KWNS 100832
SWOD48
SPC AC 100831

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0331 AM CDT Thu Oct 10 2024

Valid 131200Z - 181200Z

...DISCUSSION...
Upper troughing is expected to deepen across the central and eastern
CONUS from D4/Sunday through at least D6/Tuesday. At the same time,
ridging will build across the western CONUS. This overall pattern
will likely shift eastward by D7/Wednesday as another upper trough
approaches the West Coast. As a result, an amplified
trough/ridge/trough pattern will likely extend across the CONUS by
early D7/Wednesday.

Stable conditions are expected to prevail across the majority of the
CONUS from D5/Monday through D8/Thursday. A few thunderstorms do
appear possible from the middle to upper OH Valley into Upstate NY
and central PA on D4/Sunday as a shortwave trough and associated
surface low/cold front move through the region. Strong large-scale
ascent is anticipated ahead of the shortwave, with robust mid-level
flow moving across the region as well. However, the better low-level
moisture and associated buoyancy will be displaced south, likely
keeping the overall severe threat low.

..Mosier.. 10/10/2024

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ACUS48 KWNS 110842
SWOD48
SPC AC 110840

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0340 AM CDT Fri Oct 11 2024

Valid 141200Z - 191200Z

...DISCUSSION...
Medium-range guidance indicates that there will be substantive
further amplification of large-scale mid-level troughing to the east
of the Mississippi Valley early next week. Peak amplitude may occur
near/east of the Atlantic Seaboard early Wednesday, when cool
surface ridging may encompass much of the interior U.S. into areas
offshore of the Gulf and southern Atlantic coasts.

Although another vigorous digging short wave impulse may reinforce
the larger-scale mid-level troughing near the northern Atlantic
Seaboard into late week, a southerly return flow may develop across
the southern Great Plains toward the Upper Midwest, ahead of
significant mid-level troughing emerging from the mid-latitude
Pacific. It is possible that this could be accompanied by at least
some increase in thunderstorm development ahead of an associated
cold front Thursday through Friday. However, it is not yet clear
that low-level moistening will contribute to sufficient
destabilization to support more than low probabilities for severe thunderstorms.

..Kerr.. 10/11/2024

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ACUS48 KWNS 120850
SWOD48
SPC AC 120849

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0349 AM CDT Sat Oct 12 2024

Valid 151200Z - 201200Z

...DISCUSSION...
It still appears that an evolving large-scale eastern U.S. upper
trough will reach peak amplitude near the Atlantic Seaboard around
the middle of next week, when cool surface ridging may encompass
much of the interior U.S. into areas offshore of the Gulf and south
Atlantic coasts. Thereafter, even as the mid-level troughing
progresses into the Atlantic and loses amplitude, medium-range
guidance indicates that surface ridging will be maintained across
the northwestern Gulf coast vicinity, on the southwestern flank of a
retreating surface high.

There appears greater spread within the model output concerning
possible subsequent significant surface cyclogenesis from the lee of
the Canadian/northern U.S. Rockies through the interior higher
latitudes of Canada, in response to forcing associated with a short
wave trough emerging from the mid-latitude Pacific during the middle
to latter portion of next week. Even though this may initially
include the development of fairly deep surface troughing from the
lee of the northern U.S. Rockies into the Great Plains, it appears
that low-level Gulf moisture return will be limited. While there
may be some increase in thunderstorm activity across parts of the
Great Plains by next Thursday and Friday, the lack of widespread
appreciable destabilization will probably tend to minimize the risk
for severe thunderstorms.

..Kerr.. 10/12/2024

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ACUS48 KWNS 130847
SWOD48
SPC AC 130845

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0345 AM CDT Sun Oct 13 2024

Valid 161200Z - 211200Z

...DISCUSSION...
Initially amplified mid-level troughing near the Atlantic Seaboard
is forecast to shift offshore and lose amplitude across the western
Atlantic during the middle to latter portion of the coming work
week. In its wake, medium-range guidance indicates at least a
couple of significant short wave perturbations will emerge from a
somewhat more progressive regime across the mid-latitude latitude
Pacific.

It still appears that the lead perturbation may provide support for
strong surface cyclogenesis to the lee of the Canadian and northern
U.S. Rockies during the latter portion of this week. While there is
variance among the models concerning early evolution south of the
international border, primary cyclone development is appearing most
probable across the Canadian Prairies into higher latitudes of
interior Canada. As this occurs, a trailing cold front may overtake
modestly deep surface troughing across the northern into central
U.S. Great Plains Thursday into Friday. This could become a focus
for a corridor of increasing thunderstorm development. However, it
still appears that rather modest to weak low-level moisture return,
in the wake of a prior cool/dry intrusion as far south as the
northern Gulf of Mexico, will tend to limit destabilization and
minimize the risk for severe storms.

Models indicate that the second impulse, quickly progressing inland
behind the lead wave, will tend to split off toward the southern
mid-latitudes. However, the differences between the ECENS/ECMWF and
GEFS/GFS remain quite large concerning the amplification and
progressiveness of this perturbation across the central/southern
U.S. late this week into next weekend. Even so, with low-level
moisture return off the Gulf of Mexico initially limited, and then
perhaps impeded by the progression of the lead system, it is not
clear whether these differences will have much impact on the overall
convective potential.

..Kerr.. 10/13/2024

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ACUS48 KWNS 140840
SWOD48
SPC AC 140838

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0338 AM CDT Mon Oct 14 2024

Valid 171200Z - 221200Z

...DISCUSSION...
There appears much better consensus between the ECENS/ECMWF and
GEFS/GFS concerning the evolution of the mid/upper flow late this
week into early next week. Within larger-scale mid-level troughing
developing inland of the Pacific coast by mid week, one embedded
short wave impulse progressing northeast of the Canadian Rockies at
the outset of the period is forecast to pivot across the Canadian
Prairies into the higher latitudes of interior Canada, accompanied
by the consolidating primary surface cyclone.

It now appears probable that the significant trailing short wave
perturbation will undergo considerable amplification and split off
the main belt of westerlies, while digging inland of the northern
Pacific coast. It appears that this will include the evolution of a
deepening mid-level low near/east of the Sierra Nevada into the
Southwest, where it may linger into next weekend as low-amplitude
ridging shifts inland within the westerlies across the Canadian Rockies/Prairies and adjacent international border vicinity. As
westerly mean flow then strengthens downstream of digging
large-scale troughing off the Pacific coast late this weekend into
early next week, it appears that the low will transition to an open
wave and accelerate across the Rockies through the central Great
Plains, around the northern periphery of building ridging in the
subtropical latitudes.

Preceding the emergence of the perturbation from the Southwest, the
models continue to indicate that the development of a moistening
southerly return flow off the Gulf of Mexico will be impeded by the
maintenance of surface ridging across much of the eastern U.S.
through northwestern Gulf coast vicinity. While some strong
thunderstorm development might not be entirely out of the question, particularly Friday with some modest initial moistening near
lingering relatively deep surface troughing across the central high
plains, the risk for severe weather appears generally low through
this period.

..Kerr.. 10/14/2024

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ACUS48 KWNS 150847
SWOD48
SPC AC 150846

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0346 AM CDT Tue Oct 15 2024

Valid 181200Z - 231200Z

...DISCUSSION...
Medium-range guidance indicates that a closed low will form within
an amplifying short wave trough digging southeast of the southern
Great Basin/lower Colorado Valley by early Friday. It appears
probable that this will become cut off from the westerlies, with the
center of the modestly broad circulation lingering near or southwest
of the Four Corners into early Sunday, as low-amplitude ridging
passes by to the north, near the western through central
Canadian/U.S. border area. Sunday into Monday, models suggest that
it may come under the influence of strengthening westerly mean flow, transitioning to an open wave and accelerating northeastward into
the central Great Plains, before continuing to migrate around the
northeastern periphery of building mid-level ridging centered over
the subtropics.

Models continue to indicate that this is unlikely to become
accompanied by significant surface cyclogenesis to the lee of the
southern Rockies. And low-level moisture return in the wake of
weakening cold surface ridging across the northwest Gulf Coast
region may remain modest to weak. While modestly steep lapse rates
may contribute to isolated to widely scattered strong diurnal
thunderstorm development near surface troughing to the lee of the
Front Range, Sangre de Cristo and Sacramento Mountains Friday
through Sunday, the overall severe weather potential still appears
generally low.

..Kerr.. 10/15/2024

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ACUS48 KWNS 160824
SWOD48
SPC AC 160822

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0322 AM CDT Wed Oct 16 2024

Valid 191200Z - 241200Z

...DISCUSSION...
Latest medium-range guidance is not much different that prior runs
for this period. A fairly significant lower/mid-tropospheric
cyclone may remain centered near the Four Corners, cut off from the
westerlies, before beginning to slowly accelerate eastward on
Sunday. As the southern/southwestern flank of cool surface ridging
is generally maintained across the northern Gulf of Mexico into
northwestern Gulf coast vicinity, and impedes low-level moistening
across the southern Great Plains, the potential for severe
thunderstorm development appears likely to remain rather limited.

As the remnant perturbation progresses more rapidly east of the
southern Rockies through the interior U.S., around the northeastern
periphery of building mid-level ridging centered over the
subtropics, models continue to indicate little in the way of
appreciable surface cyclogenesis and moistening southerly return
flow. As a result, the potential for severe thunderstorm
development is expected to remain generally low through the early to
middle portion of next week.

..Kerr.. 10/16/2024

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ACUS48 KWNS 170838
SWOD48
SPC AC 170837

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0337 AM CDT Thu Oct 17 2024

Valid 201200Z - 251200Z

...DISCUSSION...
An initially evolving mid-level low is still forecast to emerge from
the Four Corners vicinity late this weekend, before accelerating
east of the southern Rockies and across the remainder of the
interior U.S., generally around the northern/northeastern periphery
of ridging centered over the subtropics. As this occurs, models
indicate similar pattern developments upstream, but over the
southern mid-latitude Pacific, with another notable mid-level low
evolving to the northwest of 30N/140W early next week, before
accelerating toward the U.S. Pacific coast by the end of the period.

While there appears at least some risk for a couple of strong storms
across the Texas/Oklahoma Panhandle vicinity into the lower central
Great Plains Sunday into Monday, the lack of a substantive return
flow of moisture from the Gulf of Mexico is still expected to
minimize the overall convective potential. Models indicate that
weak surface ridging may linger across the Gulf Coast vicinity
through much of the period, impeding the development of a moistening
southerly inland return flow and maintaining generally low risk for
severe thunderstorm activity.

..Kerr.. 10/17/2024

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ACUS48 KWNS 180834
SWOD48
SPC AC 180833

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0333 AM CDT Fri Oct 18 2024

Valid 211200Z - 261200Z

...DISCUSSION...
For this coming Monday, a shortwave trough is forecast to move into
the central Plains. Models indicate that a narrow, and increasingly
limited, band of moisture will be present ahead of the trough and
associated surface front. Though thunderstorms are possible in parts
of eastern Kansas with this activity, severe weather potential
appears low at this time.

As the central Plains trough moves east, it is expected to lose
amplitude and eventually phase with a stronger, broader upper trough
moving through the Upper Midwest and Ohio Valley region around the
middle of next week. While models begin to diverge on the
upper-level pattern at that time, the general consensus is for a
cold font to push into parts of the southern Plains as well as to
near the Gulf Coast and off the Atlantic Coast. With moisture ahead
of the front still looking limited, severe thunderstorms do not
appear probable along the boundary. Thereafter, surface ridging in
the eastern third of the CONUS, along with another upper ridge over
the Divide, will keep severe weather potential low through at least
the end of next week and possibly into next weekend.

..Wendt.. 10/18/2024

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ACUS48 KWNS 190849
SWOD48
SPC AC 190848

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0348 AM CDT Sat Oct 19 2024

Valid 221200Z - 271200Z

...DISCUSSION...
A shortwave trough is expected to move into the Midwest before
phasing with a broader upper-level trough in the Great Lakes region
by the middle of next week. Access to Gulf moisture will become more
restricted as this feature moves eastward. Across parts of the West
and Plains, an upper-level ridge will develop and shift east through
the remainder of the week into the weekend. The upper-level pattern
becomes less certain during the weekend, but at least a brief period
of quasi-zonal flow aloft is currently expected. With another
cold-frontal intrusion into the Gulf expected to occur late this
week, moisture availability/quality for any shortwave troughs moving
through the westerlies is highly uncertain. Severe weather potential
continues to appear low through next weekend.

..Wendt.. 10/19/2024

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ACUS48 KWNS 200906
SWOD48
SPC AC 200904

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0404 AM CDT Sun Oct 20 2024

Valid 231200Z - 281200Z

...DISCUSSION...
A progressive mid-level pattern will be in place across the CONUS by
the middle of this week and through the weekend. A cold front will
move through the northeast CONUS on Wednesday with occasional
lightning possible. High pressure will build in across the eastern
CONUS in the wake of this cold front. This will result in fair
weather and minimal severe weather concerns at the end of this week.
Weak lee troughing will resume late Friday and into Saturday across
the central CONUS. Some showers and thunderstorms are possible along
a cold front that will develop and move south. However, moisture
will be quite minimal and thus, the severe weather threat will be
low.

..Bentley.. 10/20/2024

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ACUS48 KWNS 211302
SWOD48
SPC AC 211300

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0800 AM CDT Mon Oct 21 2024

Valid 241200Z - 291200Z

...DISCUSSION...
A mid-level trough will cross the central and eastern CONUS on
D4/Thursday and D5/Friday with a surface front advancing east
through the period. Moisture will remain limited ahead of this front
and thus, severe weather is not expected. In the wake of this front,
high pressure will build into the Midwest on D6/Saturday and move
into the Mid-Atlantic by D7/Sunday. This will result in tranquil
weather through the weekend. Extended range guidance does suggest
the potential for some return moisture flow by early next week, but
there is considerable uncertainty in the upper-level pattern and any
potential severe weather threat would likely be after Monday/D8.

..Bentley.. 10/21/2024

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ACUS48 KWNS 220843
SWOD48
SPC AC 220842

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0342 AM CDT Tue Oct 22 2024

Valid 251200Z - 301200Z

...DISCUSSION...
Severe weather concerns will be minimal D4/Friday to D7/Monday as a
mid-level trough amplifies across the Northeast and a strong surface
high pressure center moves across the eastern CONUS in its wake. By
late in the weekend to early next week, lee troughing will return to
the Plains as a trough traverses the western CONUS. There is still
considerable uncertainty regarding the timing and evolution of this
trough, but in general, there is a consistent signal for a strong
trough to eject out of the western CONUS in the early to middle part
of next week.

Dry air has infiltrated the northern Gulf of Mexico this week with
consistent east-northeasterly flow reinforcing this more continental
airmass through the weekend. Richer low-level moisture is not
forecast to return to the entire Gulf Basin until Tuesday/D8. This
may result in limited inland moisture and instability Monday/D7 and
Tuesday D8, particularly if the trough follows some of the more
progressive guidance. However, if return flow continues for a longer
period before the primary trough ejects, a greater severe weather
threat is possible, but it would likely be beyond Tuesday/D8.

..Bentley.. 10/22/2024

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ACUS48 KWNS 230859
SWOD48
SPC AC 230857

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0357 AM CDT Wed Oct 23 2024

Valid 261200Z - 311200Z

...DISCUSSION...
Severe weather concerns will be minimal D4/Saturday to D6/Monday as
a mid-level trough amplifies across the Northeast and a strong
surface high pressure center moves across the eastern CONUS in its
wake. By late in the weekend to early next week, lee troughing will
return to the Plains as a trough traverses the western CONUS. There
is still considerable uncertainty regarding the timing and evolution
of this trough, but in general, there is a consistent signal for a
strong trough to eject out of the western CONUS in the early to
middle part of next week.

Dry air has infiltrated the northern Gulf of Mexico this week with
consistent east-northeasterly flow reinforcing this more continental
airmass through the weekend. Richer low-level moisture is not
forecast to return to the entire Gulf Basin until Tuesday/D7.
Limited moisture may surge northward on Tuesday/D7 and Wednesday/D8
with some thunderstorms possible. However, there is no clear signal
for severe weather at this time.

..Bentley.. 10/23/2024

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ACUS48 KWNS 240849
SWOD48
SPC AC 240847

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0347 AM CDT Thu Oct 24 2024

Valid 271200Z - 011200Z

...DISCUSSION...
High pressure will dominate the surface pattern across the eastern
CONUS on Sunday. Strong lee troughing will begin across the central
CONUS early next week as a large mid-level trough shifts across the
western CONUS. There is consistency among extended range guidance
for a strong ridge to build across the eastern CONUS which will
result in a positively tilted mid-level trough with multiple
embedded shortwave troughs. As these advect through the flow,
several surface lows will move from the Plains to the Upper
Midwest/Great Lakes next week. Initially, surface moisture will be
lacking across the Plains, but by the middle of the week
Day7/Wednesday, the continued southerly flow will result in better
low-level moisture with 60sF dewpoints potentially as far north as
the Midwest with mid 60s dewpoints into the southern Plains. Once
more robust low-level moisture moves inland and interacts with the
sharp surface front/trough, thunderstorms will be possible. Once
this moisture is in place, severe weather will become more possible
from Day7/Wednesday and beyond. At this time it is unclear how the
evolution of these individual shortwave troughs will occur which
will impact severe weather potential.

..Bentley.. 10/24/2024

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ACUS48 KWNS 250702
SWOD48
SPC AC 250700

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0200 AM CDT Fri Oct 25 2024

Valid 281200Z - 021200Z

...DISCUSSION...
A mid/upper trough will progress eastward from the western U.S. to
the Upper Midwest Days 4-7/Mon-Thu. As this occurs, a belt of strong
mid/upper southwesterly flow will overspread portions of the
southern/central Plains to the upper MS Valley on Day 5/Tue, and
much of the Upper Midwest/Great Lakes vicinity on Day 6/Wed. In
response, a series of surface lows will migrate across the central
Plains to the upper Great Lakes on Days 5-6/Tue-Wed. Increasing
southerly low-level flow will transport 50s to possibly low 60s F
dewpoints northward across the central/southern Plains to the
Mid/Upper MS Valley during this time. Thunderstorm potential will
increase on Day 5/Tue in this warm advection regime ahead of the
trough, and into Day 6/Wed as a cold front is forecast to progress
eastward over the central CONUS. Given strong deep-layer
southwesterly flow and increasing boundary-layer moisture to aid in destabilization, some strong to severe thunderstorms are possible.
However, capping may preclude a greater severe risk on Day 5/Tue as
midlevel temperatures are forecast to be fairly warm. By Day 6/Wed,
strong large-scale ascent may be lifting into the Great Lakes/Canada
and out of phase with better low-level moisture and modest
instability. Given uncertainty, will not introduce any 15 percent
delineations at this time, but outlook areas may be needed in
subsequent outlooks for parts of the central Plains to Upper Midwest
vicinity around Days 5-6/Tue-Wed.

Toward the end of the period, another upper shortwave trough may
eject from the western U.S. into the Plains. However, large spread
in timing and position of this feature is resulting in low
predictability from Day 7/Thu and beyond.

..Leitman.. 10/25/2024

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ACUS48 KWNS 260734
SWOD48
SPC AC 260733

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0233 AM CDT Sat Oct 26 2024

Valid 291200Z - 031200Z

...DISCUSSION...
...Tuesday/Day 4 and Wednesday/Day 5...
An upper-level trough and an associated mid-level speed max are
forecast to move across the Desert Southwest on Tuesday. Southwest
mid-level flow is forecast ahead of the system from the southern
High Plains northeastward into the upper Mississippi Valley.
Moisture advection is forecast on Tuesday within a belt of strong
low-level flow across the southern and central Plains. The moist
airmass may reach the mid Missouri Valley by Tuesday evening where
model forecasts develop scattered thunderstorms. A severe threat
will be possible across parts of the mid Missouri Valley as the
airmass moistens in response to large-scale ascent and relatively
strong deep-layer shear. Some model forecasts suggest that
convective development may be delayed until the late evening and
overnight period. The late initiation would probably keep any severe
threat isolated and marginal due the weakness in instability. Will
not add a threat area at this time due to timing uncertainty
concerning convective initiation.

On Wednesday, convective development with greater coverage is
forecast during the day from the southern Plains north-northeastward
into the upper Mississippi Valley. A moist airmass combined with
strong low-level flow and sufficient instability may result in a
severe threat during the afternoon. At this time, the potential for
severe storms appears conditional along much of the corridor from
eastern Oklahoma northeastward into Wisconsin. A severe threat area
could be needed as confidence increases over the next few model runs
concerning the area with the greatest severe potential.

...Thursday/Day 6 to Saturday/Day 8...
From Thursday to Saturday, multiple shortwave troughs are forecast
to move across the northern tier of the United States. A moist
airmass is forecast to remain in place from the southern Plains
eastward into the Gulf Coast states. Isolated to scattered
thunderstorm development will be possible over parts of this airmass
each day. However, instability and large-scale ascent is forecast to
remain relatively weak suggesting that any severe threat that
develops could remain isolated and marginal.

..Broyles.. 10/26/2024

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ACUS48 KWNS 270900
SWOD48
SPC AC 270858

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0358 AM CDT Sun Oct 27 2024

Valid 301200Z - 041200Z

...DISCUSSION...
...Wednesday/Day 4 and Thursday/Day 5...
An upper-level trough is forecast to move eastward into the central
Rockies and northern Plains on Wednesday, as an associated mid-level
jet translates eastward into the mid Missouri Valley. At the
surface, a cold front is forecast to move east-southeastward across
the Upper Midwest and central Plains. Scattered thunderstorm
development is expected along and ahead of the front during the
afternoon. Sufficient instability combined with strong low-level
flow, and lift associated with the upper-level trough will be
favorable for severe storms across parts of the region.

The most favorable area for severe storms appears to be from north
Texas and Oklahoma northeastward into western and northern Missouri.
GFS forecast soundings along this corridor during the late afternoon
suggest that MLCAPE will peak in the 1000 to 1500 J/kg range. 0-6 km
shear is forecast to be between 40 and 50 knots, with 700-500 mb
lapse in the 7 to 7.5 C/km range. If this environement can
materialize, supercell development with large hail and severe wind
gusts could occur. A chance for very large hail will be possible
with the more intense cells. An isolated tornado threat also appears
possible.

On Thursday, the upper-level trough is forecast to move into the
Great Lakes region, as the cold front advances southeastward into
the Ohio Valley and Ark-La-Tex. Isolated strong to severe storms
will be possible along parts of the front where surface temperatures
are able to warm sufficiently. The strongest low to mid-level flow
is forecast over the mid Mississippi and lower Ohio Valley
suggesting that the potential for organized severe convection could
be displaced away from the strongest instability. Even so,
instability is forecast to remain weak which appears to be the main
limiting factor.

...Friday/Day 6 to Sunday/Day 8...
On Friday, an upper-level trough is forecast to move northeastward
into the north-central U.S., as moisture return takes place in
western parts of the southern Plains. It appears that thunderstorm
development will be possible across parts of west Texas within the
northwestern part of a moist airmass. Large-scale ascent is forecast
to remain relative weak suggesting that any severe threat could be
isolated.

On Sunday, southwesterly mid-level flow is forecast over the Great
Plains, as low-level moisture advection continues. Scattered
thunderstorms will be possible within this moist airmass as surface temperatures warm during the day. At this time, forecast instability
and shear appear marginal for severe storms, and any organized
convection should be relatively isolated.

..Broyles.. 10/27/2024

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ACUS48 KWNS 280858
SWOD48
SPC AC 280857

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0357 AM CDT Mon Oct 28 2024

Valid 311200Z - 051200Z

...DISCUSSION...
...Thursday/Day 4 to Saturday/Day 6...
An upper-level trough is forecast to move eastward into the upper
Mississippi Valley on Thursday, and into the Northeast on Friday. At
the surface, a cold front is forecast to advance southeastward into
the Gulf Coast states. Thunderstorm development will be likely near
and ahead of the front Thursday afternoon and evening. Weak
instability and limited large-scale ascent should keep any severe
threat marginal.

From Friday into Saturday, low-level moisture return is expected to
take place further west into the southern Plains. Thunderstorms are
forecast to develop on Friday over parts of eastern New Mexico and
west Texas, with an isolated severe threat possible. On Saturday,
moisture and instability is forecast to increase across the southern
and central Plains, which could result in an expansion of severe
threat coverage. However, the latest models suggest that instability
will be relatively weak in most areas, helping to marginalize the
severe threat.

...Sunday/Day 7 and Monday/Day 8...
On Sunday and Monday, an upper-level system is forecast to move from
near the southern California coast into northwestern Mexico. Ahead
of the system, an anticyclonic and subtle southwesterly mid-level
flow pattern is forecast in the south-central U.S, where a moist
airmass should be located. Isolated to scattered thunderstorms are
expected to develop on both Sunday and Monday afternoons with this
airmass. The strongest instability is forecast to be near the
western edge of the moist airmass, suggesting the greatest severe
potential could be from west Texas extending north-northeastward
into the central Plains. Forecast instability should be relatively
weak, keeping any severe threat marginal.

..Broyles.. 10/28/2024

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ACUS48 KWNS 290852
SWOD48
SPC AC 290851

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0351 AM CDT Tue Oct 29 2024

Valid 011200Z - 061200Z

...DISCUSSION...
...Friday/Day 4 to Sunday/Day 6...
An upper-level trough is forecast to dig south-southeastward into
California on Friday, as southwesterly mid-level flow remains over
the Great Plains. On Saturday, an upper-level low is forecast to
close off over southern California. The southwesterly flow pattern
will be favorable for moisture advection in the southern Plains over
the weekend. Surface dewpoints are forecast to return into the 60s F
across much of the southern Plains, where scattered thunderstorms
are expected to develop both Friday and Saturday. The latest model
forecasts for this period suggest that MLCAPE will peak each
afternoon in the 500 to 1000 J/kg range, with 0-6 km shear remaining
around 30 knots. This, combined with a lack of large-scale ascent,
is expected to keep any severe threat marginal across the region.
Strong wind gusts and hail should be the primary threats.

The upper-level low is forecast to move slowly eastward towards
southwestern Arizona on Sunday, as the exit region of a mid-level
jet overspreads the southern High Plains. Weak destabilization and
moderate deep-layer shear associated with the jet should support an
isolated severe threat across parts of west Texas Sunday afternoon
and evening.

...Monday/Day 7 and Tuesday/Day 8...
On Monday and Tuesday, the mid-level jet is forecast to move across
the southern and central Plains over a weakly unstable airmass.
Thunderstorm development is expected each day from parts of central
and north Texas northward into Kansas. Although a severe threat will
be possible each afternoon, weak instability is expected to keep any
severe potential relatively isolated.

..Broyles.. 10/29/2024

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ACUS48 KWNS 300804
SWOD48
SPC AC 300803

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0303 AM CDT Wed Oct 30 2024

Valid 021200Z - 071200Z

...DISCUSSION...
...Saturday/Day 4 to Monday/Day 6...
An upper-level trough is forecast to move into the Desert Southwest
on Saturday, as southwesterly mid-level flow remains over the
Rockies and Great Plains. A moist airmass will be in place over much
of the southern and central Plains. Along the western edge of the
moist airmass, moderate instability is forecast to develop from
eastern New Mexico into west Texas. Thunderstorms that develop along
and near this instability axis will have a chance to be severe.
Supercells could produce large hail and isolated severe wind gusts.

On Sunday, low-level moisture advection is expected to continue over
much of the Great Plains, as the upper-level trough moves across the
Desert Southwest. Model forecasts are in reasonably good agreement,
with an axis of moderate instability developing Sunday afternoon
from northwest Texas into western and central Oklahoma northward
into Kansas. Moderate deep-layer shear and steep mid-level lapse
rates should support supercell development, with a potential for
isolated large hail and wind damage. The threat should persist into
the evening as scattered severe storms move eastward across the
southern and central Plains.

On Monday, the upper-level trough is forecast to move through the
southern High Plains, as an 80 to 100 knot mid-level jet ejects
northeastward into the southern and central Plains. Thunderstorms
are expected to develop along a corridor of weak instability from
central and north Texas northeastward into the Ozarks. Moderate
deep-layer shear near the instability axis should support a severe
threat during the afternoon and evening, with damaging wind gusts
and isolated large hail as the primary threats. At this time, the
timing of the ejecting mid-level jet, and magnitude of instability
remain too uncertain to issue a threat area.

...Tuesday/Day 7 and Wednesday/Day 8...
The upper-level trough is forecast to move quickly northeastward
into the Great Lakes region on Tuesday, as mid-level flow remains
southwesterly across the lower to mid Mississippi Valley. Isolated
to scattered thunderstorms are expected to form Tuesday afternoon
ahead of a cold front from the lower to mid Mississippi Valley north-northeastward into the lower Ohio Valley. On Wednesday, the
front is forecast to move southeastward into the Ohio and Tennessee
Valleys, suggesting the potential for isolated severe thunderstorms
would be greatest from Kentucky southwestward into western Tennessee
and northern Mississippi. However, spatial and magnitude uncertainty
are substantial at this range.

..Broyles.. 10/30/2024

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ACUS48 KWNS 010900
SWOD48
SPC AC 010859

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0359 AM CDT Fri Nov 01 2024

Valid 041200Z - 091200Z

...DISCUSSION...
Primary severe potential is focused on D4/Monday from parts of the south-central states into the Mid-MS Valley. An emerging squall line
should develop early morning Monday (late D3 into early D4) across
parts of west TX. This should occur ahead of strong forcing for
ascent attendant to a shortwave impulse and mid-level speed max
moving through the basal portion of a Southwest trough. Consensus of
guidance supports a positive-tilt ejection of this wave into the
central states, with multi-day trends of a weaker surface cyclone.
This should yield meridional deep-layer flow predominantly
paralleling the enlarging squall line. This will also support a
largely asymmetrical low-level flow regime, with the core of the
low-level jet rapidly advancing north-northeast from the
south-central states towards the southern Great Lakes. This should
become increasingly separated from the plume of mid 60s surface dew
points that should struggle to advect beyond the Mid-MS Valley.

The degree of instability with northward extent in OK/KS across the
Mid-MS Valley is questionable with abundant preceding convection
ahead of the probable squall line. Primary daytime severe threat may
be confined to parts of the Red River Valley and TX, with a
late-day/nocturnal severe threat extending northeast towards the
Mid-MS Valley. With weak mid-level lapse rates limiting instability
in the open warm-moist sector, along with the aforementioned
synoptic concerns, confidence is low in how widespread and vigorous
severe wind/tornado potential will be.

..Grams.. 11/01/2024

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ACUS48 KWNS 020842
SWOD48
SPC AC 020841

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0341 AM CDT Sat Nov 02 2024

Valid 051200Z - 101200Z

...DISCUSSION...
A benign pattern for appreciable severe appears likely to commence
by D4/Tuesday, although low-probability severe potential may exist
during the period. In the wake of a dampening positive-tilt
mid/upper trough near the Great Lakes on D4, an upstream shortwave
trough digging over the northern Intermountain West should evolve
into a cutoff low across the Southwest mid-week. A cold front
slowing and then stalling along the western Gulf Coast to Lower MS
Valley should be a focus for convection lingering from D3 into D4.
Weakening of both deep-layer winds and forcing for ascent will be
limiting factors to the severe-storm threat.

Modified moisture return will eventually spread back towards the
southern High Plains, in advance of the cutoff low. This suggests
increasing thunder potential on D6/Thursday, along an inverted
surface trough. Even with some ensemble members suggesting ejection
of the cutoff low onto the central/southern Great Plains late in the
period, the overall pattern appears unlikely to support greater than
15-percent severe probabilities.

..Grams.. 11/02/2024

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ACUS48 KWNS 030941
SWOD48
SPC AC 030939

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0339 AM CST Sun Nov 03 2024

Valid 061200Z - 111200Z

...DISCUSSION...
NHC is forecasting a high probability of TC formation in the
Caribbean by D2. Predictability is low along the FL Gulf Coast
vicinity regarding downstream tornado potential during D4-5, with
large spread in guidance at this time frame and beyond.

Meanwhile, modified moisture return will ensue on D4-5 over the
southern High Plains, in advance of a shortwave trough evolving into
a cutoff low across the Southwest. Given an initially inverted
surface trough, severe potential should be limited/mesoscale-focused
on D5/Thursday. With an emerging consensus of ensemble guidance
suggesting acceleration of the upper low onto the Great Plains,
severe potential may increase next weekend with broadening of the
warm-moist sector in the central states. Predictability is far too
low to warrant consideration of greater than 15 percent areas yet.

..Grams.. 11/03/2024

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ACUS48 KWNS 040906
SWOD48
SPC AC 040905

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0305 AM CST Mon Nov 04 2024

Valid 071200Z - 121200Z

...DISCUSSION...
Modified moisture return from the western Gulf will occur across TX
on D4/Thursday in advance of a slow-moving mid/upper trough over
AZ/NM. A surface anticyclone over the central High Plains to Mid-MO
Valley will support ridging southward across the southern High
Plains, with an inverted trough developing to its east. This
suggests convective development will primarily be elevated near and
west of the inverted trough. To its east, a mesoscale corridor of at
least low-probability severe should emerge across a part of west TX
in later outlooks.

Guidance suggests acceleration of the Southwest upper trough should
occur across the southern High Plains to central Great Plains on D5-6/Friday-Saturday. This overall synoptic pattern and related instability/shear combinations appear to be on the lower-end
spectrum for the OK/TX/AR/LA vicinity. But daily bouts of
mesoscale-driven severe risk are plausible. In the wake of this
wave, a lack of dry continental air intruding into the western Gulf
may yield a broader warm-moist sector beyond D8. Both 00Z ensemble
and deterministic guidance depict above-normal consistency with
indications of an amplifying upper trough around the Rockies
vicinity on D9/Tuesday.

Finally, the forecast evolution of PTC 18 into the Gulf later this
week will bear monitoring for a potential TC-tornado threat along
some portion of the coast.

..Grams.. 11/04/2024

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ACUS48 KWNS 050938
SWOD48
SPC AC 050937

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0337 AM CST Tue Nov 05 2024

Valid 081200Z - 131200Z

...DISCUSSION...
...D4-5/Friday-Saturday...
Guidance suggests acceleration of the Southwest upper trough should
occur across the southern High Plains to central Great Plains. After
an initially inverted surface trough on D3/Thursday, surface cyclone development is expected. Overall model trends have been for greater amplification of the trough and attendant surface reflection. But
spatial spread, that is noticeable on Thursday, increases further
into Friday-Saturday. In addition, very large spread persists with
the potential track of TC Rafael in the Gulf. This may render
peripheral impacts on the surrounding low-level moisture plume ahead
of the Great Plains wave. As such, confidence is low for determining
probable mesoscale-focused severe potential on D4-5 across the
south-central states.

...D8/Tuesday...
After a potential quiet period of severe potential on D6-7, guidance
consensus indicates an amplified upper trough should progress into
the West early next week. This may eventually overlap a broadening
warm/moist sector emanating north from the western Gulf and yield a
return to increasing severe potential towards mid-week. Poor
run-to-run continuity and large ensemble spread exists with the
evolution of this trough for now.

..Grams.. 11/05/2024

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ACUS48 KWNS 060938
SWOD48
SPC AC 060937

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0337 AM CST Wed Nov 06 2024

Valid 091200Z - 141200Z

...DISCUSSION...
Modest severe potential remains apparent during parts of the
extended period.

A mid/upper low over the central High Plains at 12Z Saturday should
pivot northeastward towards the Upper Midwest as it becomes an open
wave. A belt of strong mid-level southwesterlies should overlap with
the northwestern periphery of a modified low-level moisture plume
emanating north from the western Gulf. This plume is expected to be
narrower to the north-northwest of the Ark-La-Tex. Combined with
probable ongoing convection in the warm conveyor ahead of the weak
surface front, the overall severe threat on D4 should be
confined/low-end.

While outlier guidance indicates the possibility of TC Rafael
approaching the coastal LA vicinity this weekend, ensemble trends
and latest NHC forecast suggest it will probably remain over the
western Gulf.

Guidance consensus still indicates an amplified upper trough should
progress into the West early next week, with this feature reaching
the central states mid-week. This may eventually overlap a
broadening warm/moist sector emanating north from the western Gulf
across the south-central states. But poor run-to-run continuity and
large ensemble spread persist with the evolution of this trough.

..Grams.. 11/06/2024

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ACUS48 KWNS 070956
SWOD48
SPC AC 070955

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0355 AM CST Thu Nov 07 2024

Valid 101200Z - 151200Z

...DISCUSSION...
...D6-7/Tuesday-Wednesday...
Guidance consensus still indicates that an amplified upper trough
should progress into the West early next week, with this feature
reaching the central states mid-week. 00Z ensemble spread remains
large with multiple facets of the trough evolution and associated
cyclogenesis over the central states/southern Prairie Provinces. In
addition, the breadth of rich western Gulf moisture being drawn
north is uncertain. It will likely be dependent on the degree of
preceding surface ridging into the northern Gulf. The deterministic
ECMWF does appear bullish on a potential severe threat in parts of
the south-central states. This will be monitored for greater
predictability in later outlooks.

..Grams.. 11/07/2024

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ACUS48 KWNS 080840
SWOD48
SPC AC 080839

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0239 AM CST Fri Nov 08 2024

Valid 111200Z - 161200Z

...DISCUSSION...
Guidance consensus continues to indicate a broad upper trough
progressing into the West early next week, and then reaching the
central states around mid-week. Nevertheless, 00Z ensemble spread
remains large with both the degree of trough amplification and
spatiotemporal details. The GEFS has trended towards less
amplification over the West, instead favoring later over the Upper
Midwest. The ECMWF ensemble mean favors greater amplification over
the West, which is supported by its deterministic parent and
UKMET/CMC guidance. Run-to-run continuity is poor with the
degree/location of cyclogenesis east of the Rockies.

With greater confidence in a surface ridge holding across the
northern Gulf, modified moisture return appears more likely to be
limited in the southern to central Great Plains through D5/Tuesday.
The breadth of the warm-moist sector will probably enlarge by
D6/Wednesday, yielding concern for some severe potential over the
south-central states. But given poor predictability of
synoptic-scale details, consideration of an area is premature.

..Grams.. 11/08/2024

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ACUS48 KWNS 090947
SWOD48
SPC AC 090945

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0345 AM CST Sat Nov 09 2024

Valid 121200Z - 171200Z

...DISCUSSION...
Guidance agreement has increased with regard to poor-quality
moisture return ahead of an upper trough ejecting from the West into
the central states on D4-5/Tuesday-Wednesday. A preceding surface
ridge into the Gulf Coast region appears likely to inhibit
appreciable poleward advection of Gulf moisture through D5. While
differences remain in the evolution of the upper trough, guidance
has markedly shifted north with cyclogenesis centered on the
northern Great Plains. This setup appears unlikely to support an
organized severe threat.

Late week, the next broad upper trough has above-average agreement
in reaching the West Coast. Guidance indicates potentially greater
low-level moisture return from the western Gulf into the southern
Great Plains. This suggests at least a low-probability severe threat
may occur next weekend, as indicated by both SPC and NSSL GEFS-based
ML guidance, which appears supported by the 00Z ECMWF ensemble mean. Predictability is low with the evolution of embedded shortwave
impulse within this large-scale trough.

..Grams.. 11/09/2024

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ACUS48 KWNS 100926
SWOD48
SPC AC 100924

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0324 AM CST Sun Nov 10 2024

Valid 131200Z - 181200Z

...DISCUSSION...
Predictability concerns that are evident on D3/Tuesday appear to
affect the extended period. Non-GEFS/GFS models support a
slower/southward evolution of a shortwave trough across the central
states into the East on D4-5/Wednesday-Thursday. The 00Z
deterministic ECMWF/UKMET are quite similar with this scenario.
While the surface cyclone reflection may be weak, rich Gulf moisture
coupled with an increase in low-level flow may be sufficient for at
least a low-probability severe threat centered on the Lower MS
Valley to the northeast Gulf Coast/southern Deep South.

Late week, there continues to be above-average agreement with a
positive-tilt longwave trough developing from the Canadian Prairies
to off the southern CA coast. Despite typical predictability
concerns with the handling of embedded shortwave impulses, the
primary impactful difference is with the degree of moisture return
across the Great Plains. Non-GEFS/GFS models have trended towards poorer-quality return flow in the wake of the leading shortwave
trough on D4-5 and subsequent continental air mass intrusion into
the Gulf. As such, despite SPC and NSSL GEFS-based ML guidance
depicting 5-15 percent severe probabilities next weekend, other
models seemingly suggest a 5 percent or less threat for now.

..Grams.. 11/10/2024

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ACUS48 KWNS 110958
SWOD48
SPC AC 110956

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0356 AM CST Mon Nov 11 2024

Valid 141200Z - 191200Z

...DISCUSSION...
A shortwave trough should exit the Lower to Mid-Atlantic Coast on
D4/Thursday, with amplification discrepancies from D3 persisting.
The 00Z ECMWF appears to be the remaining holdout of the
deterministic guidance for a low-probability severe threat in the
northeast Gulf Coast vicinity. Still, even it suggests low-level
flow should both decrease and become veered through the day, where
rich low-level moisture exists. Instability appears likely to be
meager and overall severe potential appears low.

The next broad mid/upper trough should progress into the West by
D5/Friday. Guidance appears to be coalescing towards two distinct
shortwave impulses evolving within this longwave pattern. The lead
one is progged to track northeast into the northern Great Plains and
then pivot east across the Upper Midwest/south-central Canada over
the weekend. Meanwhile, a basal shortwave impulse should become
established off the southern CA coast. This may gradually move east
over the Desert Southwest and northwest Mexico late in the period.

Guidance continues to differ with the degree of continental airmass
intrusion into the northern Gulf, in the wake of the shortwave
trough departing the East on D4. Overall trends and likelihood of
surface ridging persisting across parts of the Gulf Coast suggest
that returning moisture will probably be of low quality in advance
of the north-central states wave. However, this may yield multiple
days of return flow and an increasingly moist warm sector becoming
established over the southern Great Plains by D8/Monday.

SPC GEFS-based ML guidance has trended down to a 2 percent
probability for D6/Saturday, after depicting a 15 percent area
yesterday. It has instead, increased probabilities to 15 percent on
D7/Sunday. Meanwhile, NSSL GEFS-based ML guidance has decreased
probabilities for D7 from 10 percent yesterday to 5 percent today.
Both of these are 5 percent or less on D8, when the ECMWF ensemble
mean would be more indicative of 15 percent potential. Given the
lack of consistency, a severe weather highlight for D7 or D8 appears
premature but bears watching in later cycles.

..Grams.. 11/11/2024

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ACUS48 KWNS 120935
SWOD48
SPC AC 120933

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0333 AM CST Tue Nov 12 2024

Valid 151200Z - 201200Z

...DISCUSSION...
Guidance still generally suggests some organized severe potential
may evolve across the south-central Plains and vicinity early next
week, though uncertainty remains high regarding the timing and
intensity of embedded shortwave troughs and the details regarding
low-level moisture return and destabilization.

On D5/Saturday, a mid/upper-level shortwave trough is forecast to
emerge from the deep, positively tilted trough over the West and
move across the northern Plains, accompanied by a deepening surface
low. While severe potential appears minimal on Saturday, the
ejecting wave is forecast to initiate low-level moisture return into
the southern Plains, which will continue into D6/Sunday and
D7/Monday.

For D6/Sunday into D7/Monday, the most important feature related to
severe potential will be a shortwave trough that may briefly evolve
into a closed mid/upper-level low somewhere over the Southwest,
before ejecting east-northeastward. Recent runs of the deterministic
ECMWF/GFS are in relatively good agreement in depicting a negatively
tilted shortwave trough ejecting into the south-central Plains on
D7/Monday. However, spread among GEFS ensemble members remains
rather high regarding the timing and evolution of shortwaves into
early next week, while the ECMWF is less aggressive with low-level
moisture return, showing only very minimal destabilization in
advance of the ejecting shortwave trough on D7/Monday.

Given the uncertainties regarding both shortwave timing and
magnitude of moisture return/destabilization, confidence is too low
to delineate a 15 percent area over some portion of the
south-central Plains for D7/Monday, the day which seems to have the
greatest relative potential at this time. It remains possible that
some severe threat could emerge as soon as D6/Sunday, and/or
potentially persist into D8/Tuesday.

..Dean.. 11/12/2024

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ACUS48 KWNS 131001
SWOD48
SPC AC 130959

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0359 AM CST Wed Nov 13 2024

Valid 161200Z - 211200Z

...DISCUSSION...
Some severe potential remains evident across parts of the
southern/central Plains (and potentially farther east) early next
week, though uncertainty remains regarding the most favored corridor
and the magnitude and sufficiency of low-level moisture/instability.

...D5/Sunday - D6/Monday...
On Saturday, a shortwave trough and attendant surface low are
forecast to move across the northern Great Plains. Low-level
southeasterly flow will result in early-stage moisture return into
the southern/central Plains, as a surface ridge shifts eastward
across the eastern CONUS. Meanwhile, a shortwave mid/upper-level
trough initially near the southern CA/Baja coast may evolve into a
closed upper-level low as it digs east-southeastward from late
Saturday into early Sunday. This trough/low is then forecast to
eject northeastward as a negatively tilted trough across parts of
the southern/central Plains from late Sunday into Monday,
accompanied by significant surface cyclogenesis.

The primary uncertainty regarding severe potential for D5/Sunday
into D6/Monday is the magnitude of low-level moisture return and destabilization across the warm sector of the developing surface
low. While low/mid 60s F dewpoints may return into parts of TX and
perhaps OK, with 50s F dewpoints farther north, limited heating and
relatively weak lapse rates will limit buoyancy, with the GFS/ECMWF
and their related ensembles suggesting MLCAPE of 500 J/kg or greater
may be confined to parts of central/south TX, with increasingly
limited buoyancy farther north.

Some severe potential could evolve on D5/Sunday, especially later in
the period when the ejecting shortwave trough may begin to impinge
on richer moisture from southwest into central TX. An intensifying
low-level jet may support development of widespread convection from
late on D5/Sunday into D6/Monday, with a strongly forced band of
convection potentially moving east-northeastward across a larger
portion of the southern/central Plains.

Despite the very limited instability that is currently anticipated
across much of the region, the intense wind fields and strong ascent
associated with the ejecting shortwave trough (as depicted by the
GFS/ECMWF and some ensemble members) could support an organized
severe threat within a low-CAPE/high-shear regime. Uncertainty
remains regarding the most favorable corridor, with the GFS/ECMWF
favoring parts of the southern/central Plains, while some ensemble
members favor a zone farther east from the ArkLaTex into the mid MS
Valley.

...D7/Tuesday - D8/Wednesday...
Some severe potential could continue into D7/Tuesday into parts of
the Midwest and Ohio Valley, though there may be a tendency for
stronger deep-layer flow and ascent to become increasingly displaced
from sufficient moisture and instability.

NHC is currently forecasting a high probability of tropical cyclone
formation late this week into the weekend across the central/western
Caribbean Sea. Predictability remains very low regarding the
possibility for this system to influence severe potential across the
Southeast toward the middle of next week.

..Dean.. 11/13/2024

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ACUS48 KWNS 141002
SWOD48
SPC AC 141000

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0400 AM CST Thu Nov 14 2024

Valid 171200Z - 221200Z

...DISCUSSION...
...D4/Sunday into D5/Monday...
Extended-range guidance generally agrees that a mid/upper-level
shortwave trough/closed low will move eastward across parts of the Southwest/northern Mexico through the day Sunday. This system will
eject northeastward as a negatively tilted shortwave trough Sunday
evening into Monday, accompanied by intense deep-layer flow fields
and significant surface cyclogenesis. Meanwhile, recent guidance has
trended toward somewhat richer low-level moisture return, with mid
to upper 60s F dewpoints spreading into parts of
southwest/central/north TX Sunday night into Monday, with at least
low 60s F dewpoints into parts of OK/KS.

Midlevel temperatures will remain relatively warm across the warm
sector, but there is greater confidence in at least modest
surface-based buoyancy (with MLCAPE of 500-1000 J/kg) developing
across parts of west/central TX Sunday night, accompanied by an
substantial increase in low-level and deep-layer shear. Isolated
severe storm potential cannot be ruled out by late afternoon into
early evening, but a notable increase in storm coverage is expected
Sunday night. Extensive convection may result in a tendency toward a linear/QLCS mode, but intense deep-layer flow and increasing
low-level shear will support a threat of severe wind gusts along
with some tornado potential. A 15% area has been added for
D4/Sunday, where intensifying flow is forecast to overlap sufficient instability amid as deep convection increases in coverage Sunday
night.

Some severe threat may persist from late D4/Sunday into at least
early D5/Monday, as the shortwave and attendant surface low continue
to eject northeastward. Uncertainty increases at this time range
regarding the northern and eastern extent of the severe threat on
D5/Monday, as richer low-level moisture potentially gets pinched off
from the stronger ascent from the ejecting shortwave trough, and
buoyancy becomes increasingly weak across the warm sector. Intense
wind fields will support some severe-wind and tornado potential
where convection can remain surface-based. There also may be some
potential for renewed storm development Monday afternoon in the
immediate vicinity of the ejecting shortwave and surface low across
the central Plains (as suggested in the 14/00Z ECMWF), though this
scenario remains quite uncertain.

A small 15% area has been included for D5/Monday, as a continuation
of the threat that begins late D4/Sunday. Depending on
destabilization trends during the day on Monday, probabilities may
eventually need to be expanded to the north and/or east of this
area.

...D6/Tuesday - D8/Thursday...
Some severe threat could linger on D6/Tuesday in the vicinity of the
MS Valley, though model spread increases substantially at this range
regarding the evolution of the upper-level pattern and occluding
cyclone over the northern Plains/upper Midwest. Otherwise, Tropical
Depression 19 has formed across the Caribbean, with the NHC forecast
track suggesting this system may eventually approach some portion of
the Gulf of Mexico. Uncertainty remains very high regarding any
severe threat with this system into mid/late next week.

..Dean.. 11/14/2024

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ACUS48 KWNS 190951
SWOD48
SPC AC 190950

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0350 AM CST Tue Nov 19 2024

Valid 221200Z - 271200Z

...DISCUSSION...
A relatively stable weather pattern will persist for much of the
Fri/D4 through Tue/D8 period, owing to a large upper trough over the
East and a ridge over the West. Low-level moisture across the CONUS
will with not return with any abundance until around Mon/D7. At that
time, models indicate a broad belt of west to southwest flow aloft
with general troughiness across the West, and rising heights
possibly over the East. Mid to upper 60s F are forecast from eastern
TX into the lower MS Valley, beneath increasing flow aloft which
could potentially yield areas of strong storms in the warm advection
regime.

..Jewell.. 11/19/2024

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ACUS48 KWNS 200906
SWOD48
SPC AC 200905

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0305 AM CST Wed Nov 20 2024

Valid 231200Z - 281200Z

...DISCUSSION...
An upper trough will move out of the northeastern states from Sat/D4
into Sun/D5, with the ridge flattening over the Plains. This will
result in a broad belt of near zonal flow across much of the CONUS,
with perhaps a slight propensity for cyclonic height curvature over
the Great Lakes into eastern Canada.

Low-level moisture return will occur gradually, especially from
Mon/D6 onward when 60s dewpoints may extend from eastern TX into the
lower MS Valley. However, not until around Tue Night/D7 do most
models show any appreciable instability, and even then it will
likely be weak. As such, severe storms are not forecast. However, a
few strong storms cannot be ruled out by around Wed/D8 due to
several days of persistent moistening, especially if a shortwave
trough can amplify within the strong flow regime.

..Jewell.. 11/20/2024

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ACUS48 KWNS 210946
SWOD48
SPC AC 210945

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0345 AM CST Thu Nov 21 2024

Valid 241200Z - 291200Z

...DISCUSSION...
Models indicate a relatively strong zonal pattern over much of the
CONUS for Sun/D4 into Mon/D5, with a shortwave trough skirting the
Great Lakes area. Then, through the Thu/D8 period, there is a
possibility of a low-amplitude trough amplification within this
strong belt of flow, moving across the southern Plains and
Southeast.

Predictability for this later scenario is low at this time, as there
is little run-to-run consistency. However, the air mass over the
western Gulf of Mexico, spreading into the lower MS Valley, will
become progressively more moist and unstable each day, and severe
weather may become possible in those areas. The initial more robust
moisture return from southeast TX across LA and southern MS/AL may
be accompanied by substantial clouds and precipitation, but stronger destabilization will be possible as the warm front potentially moves
north into the Wed/D7 to Thu/D8 time frame.

..Jewell.. 11/21/2024

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ACUS48 KWNS 220939
SWOD48
SPC AC 220938

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0338 AM CST Fri Nov 22 2024

Valid 251200Z - 301200Z

...DISCUSSION...
Models are in good agreement with the general pattern on Mon/D4,
depicting a midlevel speed max nosing into the central Plains Monday
morning, then phasing with an upper trough over the northern Plains.
This should then result in an amplified shortwave trough moving
across the Midwest and Great Lakes through Tue/D5 morning. An
associated cold front will shunt the young moist plume back south
toward the Gulf Coast.

This trough is then expected to eject northeastward toward Quebec
into Tue/D5, with a zonal flow regime across the CONUS on Wed/D6,
with slow moisture return.

Beyond this time frame, subtle differences exist regarding how
quickly the pattern may amplify, as ridging occurs over the West,
and a possible trough develops from the southern Plains into the
southeastern states. Any appreciable low-level moisture return and destabilization would likely be tied to such a trough amplification,
which is low predictability. In short, a non-zero threat of severe
storms may develop over parts of the Gulf Coast states, Thu/D7 into
Fri/D8, as moisture increases and flow aloft remains strong.

..Jewell.. 11/22/2024

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ACUS48 KWNS 230922
SWOD48
SPC AC 230920

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0320 AM CST Sat Nov 23 2024

Valid 261200Z - 011200Z

...DISCUSSION...
On Tue/D4, an upper trough will pivot northeastward from the Great
Lakes into southern Quebec, with temporary zonal flow across much of
the CONUS. Moisture along the central Gulf Coast will be quickly
shunted offshore as a cold front pushes south.

Models are in good agreement depicting another shortwave trough over
the central Rockies on Wed/D5, with some amplification possible into
the southern Plains Wed night. This trough will maintain a positive
tilt on Thu/D6 with a 65-75 kt 500 mb speed max extending from TX to
the TN/OH Valleys by 00Z Fri/D7.

During the day on Wed/D5, low pressure is forecast to develop over
OK, and will translate east/northeast into KY/TN Wed night ahead of
a cold front. South of this front, a relatively large area of mid to
upper 60s F dewpoints will develop, especially Wed night, from
eastern TX across LA and MS. Given the positive tilt of the upper
trough, winds around 850 mb will be out of the west/southwest,
reducing low-level shear somewhat. In addition, speeds are not
expected to be particularly strong. Still, thunderstorms will likely
develop late Wed/D5 over the lower MS and TN Valleys near the cold
front. Greater thunderstorm coverage is expected on Thu/D6 over much
of the Southeast and ahead of a strengthening cold front. Even with
veered low-level winds, the strong deep-layer shear and focus along
the front may provide a risk of severe/wind storms. This area will
be monitored for upgrades in later outlooks as predictability
increases.

From Fri/D7 into Sat/D8, a secondary speed max moving out of the
upper MS Valley/Great Lakes will likely phase with the southern
trough, eventually enveloping the eastern CONUS, and reinforcing
stable air behind the cold front.

..Jewell.. 11/23/2024

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ACUS48 KWNS 240933
SWOD48
SPC AC 240932

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0332 AM CST Sun Nov 24 2024

Valid 271200Z - 021200Z

...DISCUSSION...
Run-to-run model trends indicate generally faster solutions to the
evolving upper trough forecast to move across the central and
eastern CONUS.

On Wed/D4, a positive-tilt upper trough will extend from the upper
MS Valley into the Plains, with 500 mb speed max over 70 kt. This
feature is now forecast to be over the OH/TN Valley by 12Z Thu/D5,
with attendant cold front roughly from WV to southern MS/LA at that
time.

Given this trough speed and geometry, winds around 850 mb will be west-southwest to west at 40-50 kt. Elevated thunderstorms seem
likely given the antecedent dry air mass in place ahead of the
returning low-level moisture, most notably from KY/TN southward into
northern MS/AL/GA through 12Z Thu/D5. Surface-based storms may
develop across southern areas late along the front, with non-zero
damaging-gust potential given substantial deep-layer shear and wind
magnitude.

ECMWF-based solutions indicate much less storm coverage going into
Thu/D5 as the front accelerates across the Southeast, though some
lingering storms may be ongoing along the front early. Given these
trends, no severe areas will be issued.

..Jewell.. 11/24/2024

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ACUS48 KWNS 250938
SWOD48
SPC AC 250937

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0337 AM CST Mon Nov 25 2024

Valid 281200Z - 031200Z

...DISCUSSION...
For the Thu/D4 to Fri/D5 period, an upper trough over the MS/OH/TN
Valleys will continue to amplify, aided by a backside speed max
moving from the northern Plains toward the OH Valley. Given the
phasing aspect of this setup, models show appreciable variability
with timing and location of the resulting large trough, and surface
low position. However, the primary facet to severe potential will be
the less-than-optimal warm sector which will exist ahead of the cold
front.

GFS members are slower with both the front and the upper trough as
compared to ECWMF, which has the front offshore by Thu/D4 evening.
In either case, strongly veering 850 mb winds and associated drying
will impact severe potential. While predictability is currently low
due to large model spread, potential does exist for scattered strong
storms, primary over parts of AL and GA on Thursday. However, a
faster model solution could result in minimal threat over land,
except perhaps far eastern GA and the Carolinas. As such, trends
will be monitored in coming days for potential risk areas.

After this front moves offshore late Thursday, the remainder of the
period will see a relatively cool and stable pattern, with strong
northwest flow aloft persisting across the Plains, and periodic
surges of high pressure.

..Jewell.. 11/25/2024

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ACUS48 KWNS 260904
SWOD48
SPC AC 260902

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0302 AM CST Tue Nov 26 2024

Valid 291200Z - 041200Z

...DISCUSSION...
...D4/Friday...
While guidance continues to vary regarding frontal timing, even the
slower solutions have the front near or off of the Carolina coast by
12Z Friday. The trailing portion of the front will move across the
Florida Peninsula during the day. Some overlap of strong deep-layer
shear and modest instability may develop along/ahead of the front
across the peninsula, but a general weakening of large-scale ascent
with time could limit potential for robust storm development.

...D5/Saturday - D8/Tuesday...
Extended-range guidance generally depicts a persistent large-scale mid/upper-level trough over the eastern CONUS from Saturday through
Tuesday, as multiple reinforcing shortwave troughs move
southeastward from Canada. A large and persistent surface ridge is
expected to inhibit low-level moisture return from the Gulf of
Mexico, resulting in low severe potential from this weekend into
early next week.

..Dean.. 11/26/2024

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ACUS48 KWNS 270902
SWOD48
SPC AC 270900

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0300 AM CST Wed Nov 27 2024

Valid 301200Z - 051200Z

...DISCUSSION...
Severe-thunderstorm potential still appears low through the extended
range. An upper-level trough is expected to persist across the
eastern CONUS through the period, as multiple reinforcing shortwaves
move southeastward from Canada. A surface ridge covering much of the central/eastern CONUS will inhibit low-level moisture return through
most of the extended range. Guidance suggests potential for the
surface ridge to eventually shift eastward by D7/Tuesday into
D8/Wednesday, allowing for some moisture return into parts of Texas.
This could lead to an increase in thunderstorm activity, but the
displacement between stronger deep-layer flow/shear and any
appreciable surface-based instability currently appears too large to
support organized severe potential through early next week.

..Dean.. 11/27/2024

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ACUS48 KWNS 280908
SWOD48
SPC AC 280906

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0306 AM CST Thu Nov 28 2024

Valid 011200Z - 061200Z

...DISCUSSION...
Organized severe-thunderstorm potential still appears low through
most of the extended range.

A deep upper-level trough is expected to persist across the
central/eastern CONUS into at least the middle of next week, as
multiple reinforcing shortwaves move southeastward out of Canada. In conjunction with this trough, surface ridging will persist across
the Gulf of Mexico and generally maintain dry and stable conditions
for most of the CONUS. Farther west, a slow-moving mid/upper-level
trough may gradually amplify and potentially become a cut off low in
the vicinity of the Desert Southwest into northwest Mexico and Baja
California.

Guidance does suggest that gradual low-level moisture return will be
possible across parts of TX/LA from D4/Sunday into early next week,
as the surface ridge shifts eastward. This moisture return could
result in occasional thunderstorm potential within a weak
warm-advection regime, though the synoptic pattern is expected to
remain unfavorable for an organized severe threat.

By mid week, predictability regarding the synoptic pattern
substantially decreases, especially regarding if/when the potential
cut-off low begins to eject eastward across the Southwest and
southern Rockies. A faster ejection could result in some possibility
for more-organized convection across the southern Plains by late
next week, though the bulk of guidance still suggests generally low
potential through at least D7/Wednesday.

..Dean.. 11/28/2024

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ACUS48 KWNS 290800
SWOD48
SPC AC 290758

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0158 AM CST Fri Nov 29 2024

Valid 021200Z - 071200Z

...DISCUSSION...
The large-scale pattern during the Day 4-8 period will be
characterized by a series of upper troughs impacting the eastern
half of the CONUS. Meanwhile, a cut-off low within the broader
western upper ridge will persist off the southern CA and Baja
coasts.

Some thunderstorm activity is possible across parts of Texas around
Days 4-5/Mon-Tue and portions of LA/southern MS into midweek. Modest
southerly return flow ahead of a southeast-advancing cold front will
bring 60s F dewpoints into the western/central Gulf Coast vicinity
as an upper shortwave trough and surface low moves from the northern
Plains through the Midwest. Large-scale ascent will remain displaced
well to the north and destabilization is expected to be very modest,
precluding severe potential.

Otherwise, cool and stable conditions will prevail across much of
the CONUS, and thunderstorm activity will be low.

..Leitman.. 11/29/2024

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ACUS48 KWNS 300958
SWOD48
SPC AC 300956

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0356 AM CST Sat Nov 30 2024

Valid 031200Z - 081200Z

...DISCUSSION...
A series of upper-level troughs will move across the northern
Plains, Great Lakes and Northeast U.S. during the Day 4-8 time
frame. Farther west, an upper low initially near the West Coast will
move slowly east across the southwest states/northern Mexico.
Low-level moisture will gradually increase from east TX eastward
across the central Gulf Coast Tuesday/D4-Thursday/D6, however latest
GEFS and ECMWF ensemble guidance reflects only weak instability
across this area and with large-scale lift remaining displaced well
to the north. Although some thunderstorm potential may ultimately
exist within this environment, the severe weather potential remains
low. Thereafter, very limited instability suggests continued low
severe potential through the remaining outlook period.

..Bunting.. 11/30/2024

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ACUS48 KWNS 010716
SWOD48
SPC AC 010715

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0115 AM CST Sun Dec 01 2024

Valid 041200Z - 091200Z

...DISCUSSION...
A strong upper-level trough will move off the East Coast toward the
middle of this week. Additional reinforcing troughs are forecast in
its wake through the end of this week and potentially into next
weekend. This will keep a dry, continental polar airmass across the
eastern CONUS through the extended period.

Some low-level moisture will slowly drift inland across Texas and
potentially the central Gulf coast by the end of the week, however
this will likely be quickly shunted offshore with the arrival of
another cold front before any appreciable instability can develop.
Therefore, a few thunderstorms are possible along the Gulf Coast,
but minimal instability should limit any severe weather threat.

..Bentley.. 12/01/2024

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ACUS48 KWNS 020856
SWOD48
SPC AC 020855

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0255 AM CST Mon Dec 02 2024

Valid 051200Z - 101200Z

...DISCUSSION...
A strong cold front will move into the Gulf on Thursday morning with
a dry, continental polar airmass to spread across the eastern CONUS
in its wake. This will keep thunderstorm activity limited to far
south Texas late this week and into the early part of the weekend.
Eventually, the moist sector will advect inland across Texas and the
ArkLaTex ahead of an approaching mid-level trough late on Saturday
and on Sunday. The associated cold front will likely trigger some
thunderstorm activity on Sunday and Monday. However, instability
appears quite limited at this time, and therefore, a substantial
severe weather threat appears unlikely during the Day 4 to 8 period.

..Bentley.. 12/02/2024

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ACUS48 KWNS 030804
SWOD48
SPC AC 030802

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0202 AM CST Tue Dec 03 2024

Valid 061200Z - 111200Z

...DISCUSSION...
Significant low-level moisture will remain offshore through the
middle of the weekend. However, by Sunday and especially Monday, the
GFS and ECMWF both show mid 60s dewpoints inland perhaps as far
north as the Mid-Mississippi Valley. Once this moisture moves
inland, some severe weather is possible. Greatest concern at this
time is Day8/Tuesday as both the ECMWF and GFS (as well as their
ensemble mean) have a strong, positively tilted mid-level trough
moving into the southern Plains with surface cyclogenesis. Despite
the mid 60s dewpoints inland, current forecast instability from the
ECMWF and GFS remains quite weak. This combined with uncertainty
regarding timing and evolution of the trough precludes any
significant severe weather concern at this time. However, this
period will continue to be monitored as the details become more
clear.

..Bentley.. 12/03/2024

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ACUS48 KWNS 040830
SWOD48
SPC AC 040829

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0229 AM CST Wed Dec 04 2024

Valid 071200Z - 121200Z

...DISCUSSION...
After an extended period with troughing in the eastern CONUS and
ridging across the west, a pattern change is expected starting this
weekend. Ridging will start to build into the Southeast with a
series of troughs moving through the western CONUS as a more
progressive pattern evolves. As ridging builds across the Southeast,
the surface pattern will result in favorable trajectories for
significant moisture recovery across the Gulf of Mexico. Some of
this richer moisture will likely advect inland across portions of
the Gulf Coast and Southeast early next week. The inland moisture
intrusion combined with the arrival of several troughs within a
progressive pattern would suggest the potential for some severe
weather. However, there still remains uncertainty in the upper-level
pattern with an elongated, positively tilted trough from the GFS
which lacks significant cyclogenesis. In contrast, the ECMWF
eventually has a negatively tilted trough emerge from the western
trough with a surface cyclone, but it strengthens much later across
the Great Lakes with much of the mass response disconnected from the
better low-level instability.

Will continue to monitor the severe weather potential early next
week, but uncertainty remains too high to highlight any specific
periods at this time.

..Bentley.. 12/04/2024

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ACUS48 KWNS 070953
SWOD48
SPC AC 070951

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0351 AM CST Sat Dec 07 2024

Valid 101200Z - 151200Z

...DISCUSSION...
Extensive upper troughing is expected to cover much of central North
America early D4/Tuesday. This trough is then expected to continue
eastward as a shortwave trough progresses through its base, helping
to sharpen the trough and strengthening mid-level flow. Consensus
within the guidance places a 100-120 kt 500 mb jet streak from AL
through the central Appalachians on D5/Wednesday. The embedded
shortwave is forecast to continue quickly eastward/northeastward
across the Southeast and Mid-Atlantic on D5/Wednesday, helping to
induce a more negative tilt to the parent upper troughing.

A strong cold front will likely accompany this system, progressing
eastward through the MS and OH Valleys and Southeast on D4/Tuesday,
and off the East Coast on D5/Wednesday. Favorable low-level moisture
may be in place ahead of this front across the Southeast on
D4/Tuesday. However, a front-parallel orientation of the deep-layer
shear is anticipated, and buoyancy will likely remain modest,
limiting severe potential. Favorable low-level moisture may exist
ahead of the front across the Mid-Atlantic on D5/Wednesday as well.
However, poor lapse rates should keep buoyancy low and the current
expectation is that updrafts will struggle to maintain depth,
limiting the severe potential.

Consensus within the guidance is for the pattern to trend less
amplified in the wake of the strong mid-week upper trough from
D6/Thursday through D8/Saturday, with several shortwave troughs
likely traversing the more zonal flow. Guidance varies on the
location, strength, and speed of these shortwaves, but the impact of
these waves will likely be mitigated by predominantly stable surface
conditions on D6/Thursday and D7/Friday. Some moisture return may
begin on D7/Friday across the southern Plains, continuing into
D8/Saturday, but guidance currently suggests that buoyancy will
remain limited.

..Mosier.. 12/07/2024

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ACUS48 KWNS 081001
SWOD48
SPC AC 081000

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0400 AM CST Sun Dec 08 2024

Valid 111200Z - 161200Z

...DISCUSSION...
Medium-range guidance is in good agreement that a deep upper trough
will be over much of the central and eastern CONUS early
D4/Wednesday morning. At the same time, a surface low is forecast to
be over eastern PA, with an attendant cold front extending
southwestward from this low across the central Carolinas,
southeastern GA, and northern FL.

A shortwave trough is forecast to move within the larger upper
troughing, moving from the TN Valley/Southeast through the
Mid-Atlantic on D4/Wednesday. This evolution will help induce a more
negative tilt to the parent troughing while encouraging an eastward
shift and deamplification as well. The cold front will also quickly
shift eastward off the East Coast. A fairly narrow warm sector may
precede this front, but poor lapse rates will limit instability.
This low buoyancy will counter the strong shear expected, resulting
in mostly weak updrafts and tempering any severe potential.

Stable conditions are expected across the CONUS on D5/Thursday as
high pressure shifts from the northern Plains into the OH Valley.
Some modest moisture return may potentially begin across TX on
D6/Friday ahead of a low-amplitude, southern-stream shortwave trough
expected to move across the southern Plains late D6/Friday and early D7/Saturday. Guidance varies on the strength and speed of this wave,
limiting predictability, but some thunderstorms are possible across central/east TX and LA late D6/Friday and early D7/Saturday as this
wave interacts with the return moisture.

..Mosier.. 12/08/2024

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ACUS48 KWNS 090930
SWOD48
SPC AC 090928

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0328 AM CST Mon Dec 09 2024

Valid 121200Z - 171200Z

...DISCUSSION...
Cyclonic upper flow and stable low-level conditions are expected
across the central and eastern CONUS on D4/Thursday as surface high
pressure shifts from the northern Plains into the OH Valley. At the
same time, a low-amplitude, southern-stream shortwave trough is
forecast to progress across the Great Basin and Four Corners before
then continuing into the central/southern Plains on D5/Friday and
Mid MS Valley on D6/Saturday.

Surface cyclogenesis will likely precede this shortwave over the
central Plains on D5/Friday, with low-level moisture advection
anticipated over the southern Plains as well. The quality of this
moisture advection will be tempered by the strength of a preceding
cold front, with mid 60s dewpoints likely remaining confined to the
TX Gulf Coast. Even so, thunderstorms still appear possible late
Friday into early Saturday along and ahead of the cold front from
east TX into the Ozarks, and across the Lower MS Valley on
D6/Saturday. Uncertainty regarding the quality of the moisture
return (and related buoyancy) as well as general uncertainties
regarding the strength and timing of the shortwave limit overall
predictability of the severe thunderstorm potential.

..Mosier.. 12/09/2024

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ACUS48 KWNS 100958
SWOD48
SPC AC 100957

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0357 AM CST Tue Dec 10 2024

Valid 131200Z - 181200Z

...DISCUSSION...
Medium-range guidance is in good agreement that a shortwave trough
will move from the central Rockies through the central Plains on
D4/Friday. An associated surface low will take a similar track just
ahead of the parent wave, with an attendant cold front pushing
eastward across the southern/central Plains. Some modest moisture
return will precede this front, and thunderstorms appear possible
from east TX into the Lower MO Valley D4/Friday night into
D5/Saturday morning. A few strong storms are possible, but overall
buoyancy will likely remain modest due to warm mid-level
temperatures, and the highest dewpoints are expected to remain
displaced south of the better forcing.

This shortwave and attendant cold front will likely continue
eastward on into the MS Valley on D5/Saturday and through the
remainder of the eastern CONUS on D6/Sunday. Thunderstorms are
possible over portions of the Lower MS Valley and Mid-South on
D5/Saturday and the Carolinas on D6/Sunday. Limited buoyancy should
keep any severe-weather threat isolated.

Another shortwave trough is expected to move across CA and the Great
Basin on D6/Sunday and through the central Plains and Mid MS Valley
on D7/Monday. Similar to the earlier shortwave, the strongest
forcing for ascent with this shortwave is expected to remain
displaced north of the better low-level moisture and buoyancy,
likely tempering the overall severe potential. Even so,
thunderstorms are possible, and greater moisture return (and
buoyancy) is possible if the preceding cold front remains weak over
the southern Plains.

..Mosier.. 12/10/2024

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ACUS48 KWNS 110950
SWOD48
SPC AC 110948

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0348 AM CST Wed Dec 11 2024

Valid 141200Z - 191200Z

...DISCUSSION...
A progressive upper pattern is expected in the extended, with
several low-amplitude shortwave troughs forecast to traverse the
CONUS. Lead shortwave in this series will likely be over the central
Plains on D4/Saturday morning before then moving through the Mid MS
Valley by late D4/Saturday and through the OH Valley on D5/Sunday.
Another shortwave is expected to follow in the wake of the first,
progressing across the Great Basin and Four Corners on D5/Sunday and
the southern/central Plains on D6/Monday. This wave may phase with
another shortwave moving through central Canada, with resultant
troughing extended from the Canadian Prairies into the southern
Plains by D6/Monday afternoon. Yet another shortwave is currently
progged to drop from the Pacific Northwest/northern CA into the
Great Basin late D6/Monday. Guidance varies significantly on the
evolution of this wave, and its strength/maturity and location
currently have limited predictability.

Moisture return is anticipated across the Plains ahead of each of
these waves. Enough moisture and buoyancy should exist ahead of the
first shortwave to support thunderstorms, as it moves eastward on
into the MS Valley on D4/Saturday and through the remainder of the
eastern CONUS on D5/Sunday.

The most significant moisture return is currently expected ahead of
the second shortwave on D5/Sunday and D6/Monday. Thunderstorms are
likely as the shortwave and associated cold front interact with this
return moisture, although variability within the guidance of the
strength and speed of this wave results in differing areas of
highest thunderstorm coverage. Some severe appears possible,
particularly if the wave is stronger and further south as suggested
by the 00Z ECMWF.

..Mosier.. 12/11/2024

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ACUS48 KWNS 120921
SWOD48
SPC AC 120920

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0320 AM CST Thu Dec 12 2024

Valid 151200Z - 201200Z

...DISCUSSION...
Most of the medium-range guidance has trend faster and less
amplified with the shortwave trough expected to move from the Four
Corners region through the central Plains on D4/Sunday. This more
northerly progression will limit the interaction between this wave
and any returning low-level moisture, which should limit
thunderstorm potential throughout most of the day.

Another shortwave trough is expected to follow in the wake of this
lead wave, but with a more southerly track across the Southwest and
into the southern Plains. Guidance is in relatively good agreement
that this wave will move over the southern High Plains late
D4/Sunday into early D5/Monday. This wave is expected to interact
with the returning low-level moisture, with thunderstorm development
along and ahead of its associated front from central OK/north TX
into the Ozarks early Monday morning. Thunderstorms are expected to
gradually shift eastward throughout the day D5/Monday, expanding
into more of east/southeast TX and the Mid/Lower MS Valley.
Seasonally warm and moist conditions are anticipated, and enough
buoyancy and shear could be in place for severe thunderstorms.
However, overall buoyancy will likely be mitigated by poor lapse
rates, and warm mid-level temperatures could contribute to some
inhibition. There is also some potential for a more front-parallel
orientation, which could result in a more anafrontal character to
the storms. These factors, combined with the notable variability
within the guidance, introduce enough uncertainty to merit
withholding any severe probabilities for D4/Sunday or D5/Monday with
this outlook.

Another shortwave trough may progress into the Plains on
D7/Wednesday, with preceding moisture return across the southern
Plains setting up the potential for thunderstorms as this wave and
its associated cold front push eastward/southeastward across the
southern Plains. However, GEFS members show large differences on how
this wave progresses, with notable differences within the ECMWF
members too. Some members within both of these ensemble systems
suggest the development of a closed low over the Southwest instead
of progressive wave into the Plains. Consequently, as with the
earlier wave, predictability issues limit forecast confidence.

..Mosier.. 12/12/2024

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ACUS48 KWNS 130939
SWOD48
SPC AC 130937

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0337 AM CST Fri Dec 13 2024

Valid 161200Z - 211200Z

...DISCUSSION...
A shortwave upper trough will traverse the Midwest and Great Lakes
region on Day 4/Mon. Meanwhile, a cold front will track southeast
across the southern Plains and Mid-South vicinity, extending from
northern AL toward the Upper TX Coast/south-central TX by early Day
5/Tue. Southerly low-level flow ahead of the front will bring Gulf
moisture across the south and east Texas into the lower MS
Valley/central Gulf coast region, aiding in modest destabilization
on Monday. However, stronger mid/upper level flow and large-scale
ascent will remain north over the Midwest. Furthermore, deep-layer
flow will mostly be parallel to the cold front. As a result,
warm-advection precipitation and thunderstorms are likely from east
TX into the Lower MS Valley, but severe potential appears limited.

The cold front from Day 4/Mon will likely stall on Day 5/Tue across
parts of the TX coast and Lower MS Valley. By late Tuesday into Day
6/Wed, another upper trough is expected to eject across the Plains
into the Southeast. A sharper cold front associated with this system
will move offshore the Gulf coast, with some potential for heavy
rain and thunderstorms. However, given prior days' convection, poor heating/widespread cloudiness and weak instability, severe potential
is not expected. Given the strong cold front intruding into the
Gulf, boundary-layer moisture will become scant and severe-
thunderstorm potential is expected to be low Days 7-8/Thu-Fri.

..Leitman.. 12/13/2024

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ACUS48 KWNS 140828
SWOD48
SPC AC 140827

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0227 AM CST Sat Dec 14 2024

Valid 171200Z - 221200Z

...DISCUSSION...
An upper trough over the High Plains vicinity Day 4/Tue morning will
deepen and track east to the MS Valley by Day 5/Wed, and to the
Atlantic coast by Day 6/Thu. As this occurs, a cold front will move
across the south-central and southeast states, pushing offshore the
Gulf and Atlantic coasts by late Day 5/Wed into early Day 6/Thu.
While thunderstorm potential will be possible with this system,
severe potential appears limited, given weak instability and
deep-layer flow oriented parallel to the surface boundary (leading
to more anafrontal processes).

With the strong front moving well into the Gulf of Mexico,
boundary-layer moisture will remain scant heading into the end of
the forecast period, and severe-thunderstorm potential is expected
to remain low Days 7-8/Fri-Sat.

..Leitman.. 12/14/2024

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ACUS48 KWNS 150913
SWOD48
SPC AC 150912

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0312 AM CST Sun Dec 15 2024

Valid 181200Z - 231200Z

...DISCUSSION...
A surface cold front will move south and east across the eastern and southeastern U.S. on Day 4/Wed, moving offshore the Gulf and
Atlantic coasts by early Day 5/Thu. Showers and thunderstorms are
possible near the cold front across parts of the Southeast and
Mid-Atlantic vicinity on Day 4/Wed. However, weak instability and
only modest vertical shear is expected to limit severe thunderstorm
potential.

After Day 4/Wed, a mean upper level trough will persist over the
eastern half of the CONUS, while an amplified upper ridge develops
over the West. As the early period cold front continues to intrude
southward across the Gulf of Mexico, boundary-layer moisture will
become scant across the CONUS, and offshore trajectories will
persist through the period. This overall pattern will result in
limited thunderstorm potential beyond Day 4/Wed, and severe storms
are not expected.

..Leitman.. 12/15/2024

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ACUS48 KWNS 160948
SWOD48
SPC AC 160947

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0347 AM CST Mon Dec 16 2024

Valid 191200Z - 241200Z

...DISCUSSION...
Medium range guidance is in fairly good agreement that an amplified
but progressive upper level pattern will overspread the CONUS during
the Day 4-8 period. A shortwave trough over the northern Plains
early on Day 4/Thu will deepen and spread east over the eastern half
of the CONUS through Day 6 or 7/Sat or Sun. Meanwhile, an amplified
upper ridge will build over the western states and spread east into
the Plains during this same time period. Spread among guidance
increases around Day 6-8/Sat-Mon, but still indicates that another
upper trough will emerge over the Plains and Midwest late in the
period.

A surface cold front will move south and east into the Gulf of
Mexico and offshore the Atlantic coast on Thursday. This will clear
out any lingering boundary-layer moisture and persistent offshore
trajectories will mostly preclude much thunderstorm potential for
most of the forecast period. The exception may be on Day 7-8/Sun-Mon
as lee troughing allow for southeasterly flow to return across the
western Gulf and TX, bringing modest moisture northward across
southern/central TX. Nevertheless, severe-thunderstorm potential
appears low throughout the forecast period.

..Leitman.. 12/16/2024

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ACUS48 KWNS 170934
SWOD48
SPC AC 170933

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0333 AM CST Tue Dec 17 2024

Valid 201200Z - 251200Z

...DISCUSSION...
Strong surface high pressure over the central U.S. and a prior cold
front intruding into the southern Gulf of Mexico will result in a
dearth of boundary layer moisture across much of the CONUS through
at least Day 6/Sun. As a result, thunderstorm chances will be low.
Toward the end of the period, some forecast guidance suggests lee
troughing will allow southeasterly low-level flow to bring modest
Gulf moisture northward across TX. This may result in some increased thunderstorm chances across south/central TX on Day 7-8/Mon-Tue.
However, severe-thunderstorm potential will remain low during the
Day 4-8 time frame.

..Leitman.. 12/17/2024

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ACUS48 KWNS 180940
SWOD48
SPC AC 180939

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0339 AM CST Wed Dec 18 2024

Valid 211200Z - 261200Z

...DISCUSSION...
Strong surface high pressure and a dearth of boundary-layer moisture
will preclude severe thunderstorm potential on Days 4-5/Sat-Sun.

By Day 6/Mon, medium range forecast guidance shows a series of upper
shortwave troughs shifting east from the Rockies to the MS Valley
through Day 8/Wed (Christmas Day). In response, lee
troughing/surface low developing is expected over parts of the
southern Plains. Increasing southerly low-level flow will support
modest northward transport of Gulf moisture across parts of TX into
OK, and eventually the Lower MS Valley near the end of the period.
While there is still quite a bit of spread with regards to
intensity, location, and timing of these features, increasing
thunderstorm activity is expected Day 6-8/Mon-Wed across the
southern Plains vicinity. While uncertainty is high, if timing and
overlap of key features comes to fruition, some severe risk could be
possible over the upcoming Christmas holiday period.

..Leitman.. 12/18/2024

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ACUS48 KWNS 190846
SWOD48
SPC AC 190845

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0245 AM CST Thu Dec 19 2024

Valid 221200Z - 271200Z

...DISCUSSION...
Strong surface high pressure and a dearth of boundary-layer moisture
will limit thunderstorm potential on Day 4/Sun. Starting Day 5/Mon,
a progressive upper level pattern is forecast, and a series of
shortwave trough will migrate across the Plains to the Midwest. As
this occurs, surface lee troughing will support south/southeasterly
low-level flow across the southern Plains and the Gulf of Mexico.
Modest boundary-layer moisture will being to return northward across
TX toward OK by early next week, and eventually into the Lower MS
Valley by mid to late in the week. Large spread remains regarding
the timing and intensity of these features across the south-central
U.S. However, thunderstorm potential will begin increasing starting
Day 5/Monday across OK/TX, shifting east with time through Day
8/Thu. Some severe-thunderstorm potential could accompany this
activity, but predictability is too low at this time to include
outlook delineations at this time.

..Leitman.. 12/19/2024

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ACUS48 KWNS 200905
SWOD48
SPC AC 200904

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0304 AM CST Fri Dec 20 2024

Valid 231200Z - 281200Z

...DISCUSSION...
A more active southern-stream pattern should evolve next week, with
several lower latitude troughs crossing the southern tier along with
some northward increase in low-level moisture across parts of Texas
to the Lower Mississippi Valley and Gulf Coast. One such shortwave
trough should influence increasing thunderstorm potential across
east/southeast Texas on Tuesday/Day 5. Some severe risk could
materialize, but it appears that overall buoyancy will be weak with
the severe potential currently expected to be relatively marginal
and isolated in nature.

An additional focus for increasing deep convective potential will be
into the Thursday/Day 7 and Friday/Day 8 time frame. This will be as
a secondary upper trough emerges from the Southwest deserts. This
could lead to some severe risk in a corridor from east/southeast
Texas and ArkLaTex to Lower Mississippi Valley. However, there is
some uncertainty regarding moisture/destabilization given the
potential influences of the preceding shortwave trough and cold
front. Forecast uncertainties at this time frame precludes any 15%
outlook areas.

..Guyer.. 12/20/2024

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ACUS48 KWNS 210923
SWOD48
SPC AC 210922

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0322 AM CST Sat Dec 21 2024

Valid 241200Z - 291200Z

...DISCUSSION...
A more active southern-stream pattern is expected next week with
several lower latitude troughs crossing the southern tier, along
with some northward increase in low-level moisture across parts of
Texas to the Lower Mississippi Valley and Gulf Coast. On Tuesday/Day
4, one such shortwave trough should influence increasing
thunderstorm potential across south-central to east/southeast Texas.
Some severe risk could materialize Tuesday, but it appears that
overall buoyancy will be weak with the severe potential currently
expected to be relatively marginal and isolated in nature.

An additional focus for increasing deep convective potential will be
into the Thursday/Day 6, Friday/Day 7, and Saturday/Day 8 time
frame. This will be as a secondary upper trough emerges from the
Southwest deserts and moves toward the Deep South. This could lead
to a severe risk in a corridor from east/southeast Texas and the
ArkLaTex to Lower Mississippi Valley. While some severe storms will
be possible, perhaps especially Thursday/Day 6, there is lingering
risk magnitude uncertainty related to moisture/destabilization given
the potential influences of the preceding shortwave trough and cold
front. Forecast uncertainties at this time frame precludes any 15%
outlook areas.

..Guyer.. 12/21/2024

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ACUS48 KWNS 221002
SWOD48
SPC AC 221000

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0400 AM CST Sun Dec 22 2024

Valid 251200Z - 301200Z

...DISCUSSION...
A moderately amplified and more active/progressive southern-stream
pattern is still expected later this week, along with a general
northward fluctuation of low-level moisture across parts of Texas to
the Lower Mississippi Valley and Gulf Coast.

After a day of little or no severe-weather potential on Christmas
Wednesday/Day 4, severe risks are expected to increase into Days 5-7 Thursday-Saturday. A secondary upper trough is expected to emerge
from the Southwest deserts and moves toward the Ozarks/Deep South.
This could lead to at least a low-end multi-day severe risk in a
corridor from east/southeast Texas and the ArkLaTex to Lower
Mississippi Valley. In particular, Thursday/Day 5 could ultimately
warrant Slight Risk-caliber severe probabilities across
east/southeast Texas, especially if the more southern and more
severe-favorable ECMWF model runs become more apparent.

..Guyer.. 12/22/2024

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ACUS48 KWNS 230956
SWOD48
SPC AC 230955

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0355 AM CST Mon Dec 23 2024

Valid 261200Z - 311200Z

...DISCUSSION...
Severe-weather potential is still expected for Days 4-6
Thursday-Saturday, as an upper trough emerging from California and
the Southwest deserts moves toward the Ozarks/Deep South by
Thursday/Day 4. At least a low-end multi-day regional severe risk is
expected across south-central and east/southeast Texas towards parts
of the ArkLaTex, and possibly the Lower Mississippi Valley. In
particular, Thursday/Day 4 could ultimately warrant Slight
Risk-caliber severe probabilities across south-central to
east/southeast Texas although guidance variability persists, while objective/machine-learning guidance generally also persist with
sub-15 percent probabilities.

..Guyer.. 12/23/2024

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ACUS48 KWNS 241000
SWOD48
SPC AC 240959

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0359 AM CST Tue Dec 24 2024

Valid 271200Z - 011200Z

...DISCUSSION...
At least some severe-weather potential is expected across East Texas
and the Deep South for Friday/Day 4 and Saturday/Day 5. On
Friday/Day 4, a secondary shortwave trough may evolve across the
southern Plains in the wake of the shortwave trough related to
Thursday's/Day 3 severe potential. While some severe storms could
occur across east/southeast Texas toward the ArkLaTex on Friday/Day
4, details of available buoyancy are uncertain, especially given the
short periodicity between these mid-level systems. Similarly, a
severe storm risk could shift eastward toward the Lower
Mississippi/Mid-South on Saturday/Day 5, but confidence in 15+
percent probabilities is currently limited. Severe storm potential
is then expected to be relatively low into Days 6-8 Sunday-Tuesday.

..Guyer.. 12/24/2024

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ACUS48 KWNS 251003
SWOD48
SPC AC 251002

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0402 AM CST Wed Dec 25 2024

Valid 281200Z - 021200Z

...DISCUSSION...
At least some severe-weather potential is expected this weekend
including Saturday/Day 4 and possibly Sunday/Day 5. On Saturday/Day
4, the next in a series of shortwave troughs is expected to shift
eastward over the southern Plains and Ozarks. Given the influence of
the upper-level system and proximity of low-level moisture, at least
some severe risk appears likely across the Lower Mississippi Valley
to Tennessee Valley, including parts of Louisiana to Mississippi and
Alabama. However, the short periodicity in the wake of the prior
shortwave trough, plus the possibility of extensive early day
precipitation, currently limits confidence in placement of a 15+
percent severe risk area, although Slight Risk-caliber potential may
become more evident in future outlooks.

The severe-storm risk should shift eastward across the Southeast
States on Sunday/Day 5, but probably on a more isolated/marginal
basis. Severe storm potential should be relatively low early next
week into Days 6-8 Monday-Wednesday.

..Guyer.. 12/25/2024

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ACUS48 KWNS 261011
SWOD48
SPC AC 261010

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0410 AM CST Thu Dec 26 2024

Valid 291200Z - 031200Z

...DISCUSSION...
At least some severe-weather risk is expected on Sunday/Day 4 across
the Southeast States as an upper trough shifts east-northeastward
from the Ohio/Tennessee Valleys toward the Appalachians. Very strong
deep-layer winds will overspread the region, but guidance
variability exists regarding the availability and
north-northeastward extent of minimal buoyancy, especially with GFS/ECMWF-related guidance depicting the possibility of considerable
scattered convection ongoing Sunday morning. Regional areas
including northern Florida into southern/eastern Georgia and parts
of the Carolinas will continue to be reevaluated in subsequent
outlooks as far as Sunday's severe potential, but at least
some/low-end severe risk seems probable even with these instability uncertainties.

Thereafter, severe-weather potential early next week is currently
expected to remain low.

..Guyer.. 12/26/2024

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ACUS48 KWNS 271000
SWOD48
SPC AC 270958

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0358 AM CST Fri Dec 27 2024

Valid 301200Z - 041200Z

...DISCUSSION...
Overall severe-weather potential should remain relatively low next
week, largely attributable to a frontal intrusion into the Gulf of
Mexico on Day 3/Sunday. Air mass modification/modest-caliber
elevated moisture return may occur Monday/Day 4 from the western
Gulf of Mexico into southeast Texas and Lower Mississippi Valley, as
a shortwave trough amplifies over the southern Plains and Ozarks. A
few strong storms cannot be entirely ruled out late Monday, but such
potential should remain low overall. Additional low-level moistening
will occur across parts of the Gulf Coast and Southeast on
Tuesday/Day 5 ahead of the amplifying mid-level trough and
associated cold front, but again, overall severe potential should
remain low given the moisture and instability limitations.

Convective potential should be very low, perhaps virtually nil,
between Wednesday-Friday Days 6-8 as cold/stable continental
trajectories prevail east of the Rockies.

..Guyer.. 12/27/2024

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ACUS48 KWNS 280958
SWOD48
SPC AC 280957

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0357 AM CST Sat Dec 28 2024

Valid 311200Z - 051200Z

...DISCUSSION...
A strong upper trough and associated surface low/cold front will
move towards the Mid-Atlantic and southeast U.S. coast Tuesday, and thunderstorms will be possible within a weakly unstable warm sector
as large-scale ascent increases during the day. Confidence in the
potential for stronger storms is low given the spatially confined
area and expected weak destabilization.

During the remainder of the week and, despite some model/ensemble
variability, there is general agreement on an eastern CONUS upper
trough and a ridge across the western U.S. This pattern does not
favor substantial/rapid moisture return in the wake of the prior
cold frontal passage, and overall thunderstorm chances will be very
low to nil Wednesday through Saturday.

..Bunting.. 12/28/2024

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ACUS48 KWNS 290949
SWOD48
SPC AC 290947

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0347 AM CST Sun Dec 29 2024

Valid 011200Z - 061200Z

...DISCUSSION...
A broad/expansive upper-level trough will persist over much of the
eastern U.S. during the upcoming week, while a ridge of high
pressure will extend over the western portion of the CONUS. A series
of surface high-pressure systems will result in generally dry/stable
conditions and minimal to no chance for thunderstorms through
Friday/Day 6. Towards Saturday/Sunday (Days 7 and 8), guidance is
varied but does suggest some increase in thunderstorm potential over
the south-central U.S. as an impulse over the western U.S. moves
east of the Rockies. Uncertainty is high at this relatively extended
range on the timing and degree of amplification of this feature, and
therefore the overall potential for thunderstorms remains low with
this outlook.

..Bunting.. 12/29/2024

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ACUS48 KWNS 300933
SWOD48
SPC AC 300931

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0331 AM CST Mon Dec 30 2024

Valid 021200Z - 071200Z

...DISCUSSION...
Thunderstorm chances will likely be limited on D4/Thursday and
D5/Friday as airmass over the CONUS remains too cold and dry. Some
airmass modification may begin across the southern Plains late
d5/Friday or early D6/Saturday as a shortwave trough progresses
across the western CONUS. As the upper pattern trends more zonal
across the central CONUS, surface lee troughing will sharpen, with
low-level flow forecast to strengthen amid the increasing surface
pressure gradient. The approaching shortwave trough is expected to
continue its eastward progression into the Plains on D6/Saturday and
D7/Sunday, resulting in potential interaction with this return
moisture from central/eastern portions of TX/OK into the Lower MS
Valley. All aspects of the approaching shortwave trough remain
uncertain, with deterministic guidance showing large run-to-run
variability and notable difference between the GEFS and EPS. As
such, overall forecast confidence is low. However, the overall
trends suggests some severe potential may materialize late this
weekend into early next week.

..Mosier.. 12/30/2024

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ACUS48 KWNS 310923
SWOD48
SPC AC 310922

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0322 AM CST Tue Dec 31 2024

Valid 031200Z - 081200Z

...DISCUSSION...
Expansive ridging is forecast to gradually shift from the Plains
into the MS Valley and Southeast on D4/Friday, with stable
conditions prevailing.

A shortwave trough is expected to progress from the western Great
Basin through the Four Corners and into central/southern High Plains
on D5/Saturday, continuing eastward across central/southern Plains
and Mid/Lower MS Valley on D6/Sunday. Surface cyclogenesis appears
probable over the southern High Plains on D5/Saturday ahead of the
approaching shortwave, with a warm sector characterized by mid 60s
dewpoints likely to precede the resulting surface low and attendant
cold front. Thunderstorms are possible from central TX/OK eastward
through the Lower MS Valley on D6/Sunday, as the cold front
interacts with the moderately moist and buoyant air within the warm
sector. Deep-layer vertical shear is expected to be strong enough to
support organized storms (i.e. greater than 40 kt from 0-6 km).

Mid/upper level pattern is similar between the EPS and GEFS, but the
surface pattern has notable differences, with most GEFS members
favoring a slower and more southerly track to the surface low. This
is matched by the deterministic runs of the ECMWF and GFS, while the
Canadian splits the difference. Even though some severe appears
probable, these differences limit the forecast confidence, making it
difficult to ascertain the most likely corridor for severe
thunderstorms. Additionally, all of the deterministic guidance
continues to show notable run-to-run variability. All of these
factors combined with the extended range of the possible severe
(i.e. Day 6) result in too much uncertainty to delineate any risk
areas with this outlook.

The risk for thunderstorms will likely continue along the Gulf Coast
on D7/Monday as this system continues eastward. By D8/Tuesday, cold
and dry conditions are anticipated across the entire CONUS.

..Mosier.. 12/31/2024

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ACUS48 KWNS 010940
SWOD48
SPC AC 010939

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0339 AM CST Wed Jan 01 2025

Valid 041200Z - 091200Z

...DISCUSSION...
A shortwave trough is expected to progress from the western Great
Basin through the central Rockies and into central/southern Plains
on D4/Saturday, continuing eastward across the Mid/Lower MS Valley
on D5/Sunday. Surface cyclogenesis is anticipated ahead of this wave
over the southern High Plains on D4/Saturday, with the resulting low
tracking eastward across OK. Strengthening low-level southerly flow
ahead of this low will result in moderate moisture advection, with a
warm sector characterized by 60s dewpoints preceding the low and its
attendant cold front.

Thunderstorms are possible from central TX/OK eastward through the
Lower MS Valley on D5/Sunday, as the cold front interacts with the
moderately moist and buoyant air within the warm sector. Deep-layer
vertical shear is expected to be strong enough to support organized
storms (i.e. greater than 40 kt from 0-6 km). Latest deterministic
runs of the ECMWF and GFS continued to show notable differences,
particularly with the overall speed of the shortwave and its
associated surface low. However, EPS and GEFS members shows greater consistency, with numerous members placing the surface low over the
AR vicinity by D5/Sunday evening. Consequently, there is increased
confidence that the environment over the Lower MS Valley will
support severe thunderstorms D5/Sunday afternoon, with the threat
potentially continuing into the Southeast overnight.

The risk for thunderstorms will likely continue across the Southeast
on D6/Monday as this system continues eastward. Cold and dry
conditions are anticipated across the entire CONUS on D7/Tuesday and D8/Wednesday.

..Mosier.. 01/01/2025

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ACUS48 KWNS 020918
SWOD48
SPC AC 020916

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0316 AM CST Thu Jan 02 2025

Valid 051200Z - 101200Z

...DISCUSSION...
Medium-range guidance is in relatively good agreement that a
shortwave trough will extend from western/central KS into the TX
Hill Country early D4/Sunday morning. This shortwave is then
forecast to progress northeastward throughout the day, likely
reaching the Mid MS Valley by D5/Monday morning. An associated
surface low will move just ahead of the parent shortwave, with an
attendant cold front sweeping eastward across east TX and Lower MS
Valley. A warm sector characterized by low to mid 60s dewpoints will
precede this front, which should be sufficient for modest buoyancy
despite a relatively warm profile and poor lapse rates.

Thunderstorm development is anticipated along the front, with some
potential for isolated discrete storms ahead of the front as well.
Moderate to strong mid-level flow will extend across the warm
sector, resulting in deep-layer vertical shear strong enough to
support organized storms (i.e. 0-6 km bulk shear from 40 to 50 kt).
General expectation is for the development of a fast-moving
convective line capable of strong to severe gusts along the cold
front, supported by modest buoyancy and deep-layer shear orthogonal
to the front. Strengthening low-level flow (i.e. 50 to 60 kt at 850
mb) could also support enough low-level shear for line-embedded
circulations as well.

Some thunderstorms will remain possible across the Southeast on
D5/Monday as the front continues eastward. However, limited
low-level moisture ahead of the front should limit the severe
thunderstorm threat.

From D6/Tuesday through D8/Thursday, cold and stable conditions are
expected to preclude thunderstorm development across the CONUS.

..Mosier.. 01/02/2025

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ACUS48 KWNS 030942
SWOD48
SPC AC 030940

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0340 AM CST Fri Jan 03 2025

Valid 061200Z - 111200Z

...DISCUSSION...
A mid-level trough is forecast to progress eastward into the eastern
U.S. on Monday/Day 4, as an associated cold front moves across the
Atlantic Seaboard. Marginally severe thunderstorms could develop
along or ahead of the front early in the day from Florida northward
into the Carolinas. From Tuesday/Day 5 to Friday/Day 8, cold and dry
high pressure is forecast to settle in across much of the
continental U.S., which is expected to limit thunderstorm potential
in almost all areas.

..Broyles.. 01/03/2025

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ACUS48 KWNS 040944
SWOD48
SPC AC 040943

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0343 AM CST Sat Jan 04 2025

Valid 071200Z - 121200Z

...DISCUSSION...
A series of upper-level troughs are forecast to move through the
central and eastern U.S. next week, as cold and dry high pressure
dominates over most of the continental U.S. Conditions appear
unfavorable for thunderstorms through Thursday/Day 6. On Friday/Day
7 into Friday night, a large-scale upper-level trough is forecast to
move through the central U.S. At this time, a surface low is
forecast to move from the northern Gulf of Mexico into the
Southeast. Some moisture return will be possible with this system in
the central Gulf Coast states on Friday/Day 7, where isolated
thunderstorms will be possible. A few storms may again develop on
Saturday/Day 8 as the systems affects the Florida Peninsula. No
severe threat is expected in the Day 4 to 8 period.

..Broyles.. 01/04/2025

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ACUS48 KWNS 050957
SWOD48
SPC AC 050955

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0355 AM CST Sun Jan 05 2025

Valid 081200Z - 131200Z

...DISCUSSION...
A mid-level trough will move through the eastern U.S. on Wednesday,
as another mid-level trough moves across the Desert Southwest. This
second trough is forecast to move into the Rockies on Thursday/Day 5
and into the Great Plains on Friday/Day 6. Some thunderstorm
activity will be possible across parts of the Texas Coastal Plain
Thursday night, and along the central Gulf Coast on Friday. Ahead of
the system, moisture return is forecast to be minimal across the
western and central Gulf Coast. The airmass overland is expected to
be relatively stable, minimizing any convective potential. As the
mid-level system continues to move eastward, thunderstorms could
develop over parts of Florida on Saturday, with any storms moving
off the coast into the Atlantic on Sunday. Throughout the Day 4 to 8
period, instability is expected to be very limited minimizing any
chance for thunderstorms, and making severe storms very unlikely.

..Broyles.. 01/05/2025

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ACUS48 KWNS 060948
SWOD48
SPC AC 060947

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0347 AM CST Mon Jan 06 2025

Valid 091200Z - 141200Z

...DISCUSSION...
At mid-levels, a low is forecast to move into the southern High
Plains on Thursday/Day 4, as southwesterly flow develops over the
south-central U.S. The system will move High Plains on Thursday to
the Southeast by Saturday. Ahead of the associated trough, moisture
return is expected to be limited. This will keep instability mostly
offshore over the Gulf of Mexico. A few thunderstorms could develop
near the western and central Gulf Coast on Thursday and Friday as
the trough passes by. The focus for thunderstorm activity is
forecast to shift eastward into Florida by Saturday. Any severe
threat with this system should be minimal. On Sunday and Monday,
surface high pressure is again forecast to become dominant across
the continental U.S. Cold and dry air will make conditions
unfavorable for thunderstorms.

..Broyles.. 01/06/2025

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ACUS48 KWNS 070947
SWOD48
SPC AC 070945

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0345 AM CST Tue Jan 07 2025

Valid 101200Z - 151200Z

...DISCUSSION...
A mid-level trough is forecast to move across the southern Plains on
Friday/Day 4, as flow ahead of the system remains southwesterly over
much of the Southeast. At the surface, a front is forecast to move
into the central Gulf Coast region, with a moist airmass located
ahead of the front mostly offshore. Thunderstorm activity will be
possible from Friday into Saturday along and ahead of the front at
the northern edge of this moist airmass in the coastal sections from
Louisiana to Florida. From Sunday/Day 6 to Tuesday/Day 8,
large-scale mid-level troughing is forecast to persist over the
central U.S. In response, high pressure is forecast to remain
dominant over much of the continental U.S. late in the Day 4 to 8
period. Due to this cold and dry airmass, thunderstorms will be
unlikely.

..Broyles.. 01/07/2025

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ACUS48 KWNS 080939
SWOD48
SPC AC 080937

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0337 AM CST Wed Jan 08 2025

Valid 111200Z - 161200Z

...DISCUSSION...
A series of mid-level troughs will move across the continental U.S.
through the middle of next week, as a prevailing northwest flow
pattern continues. In response, a cold and dry airmass will remain
anchored over most of the continental U.S. throughout the Day 4 to 8
period, making thunderstorm development unlikely in most areas.

..Broyles.. 01/08/2025

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ACUS48 KWNS 090941
SWOD48
SPC AC 090940

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0340 AM CST Thu Jan 09 2025

Valid 121200Z - 171200Z

...DISCUSSION...
A northwest mid-level flow pattern is forecast to remain in place
over the central U.S. throughout the Day 4 to 8 period, as a series
of shortwave troughs move southeastward through the flow. The
northwesterly flow will help to drive multiple fronts southward into
the central and eastern U.S, which will keep a relatively cold and
dry airmass in place. For this reason, conditions are not expected
to be favorable for thunderstorm development across the continental
U.S. through the middle of next week.

..Broyles.. 01/09/2025

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ACUS48 KWNS 100918
SWOD48
SPC AC 100916

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0316 AM CST Fri Jan 10 2025

Valid 131200Z - 181200Z

...DISCUSSION...
A broad northwest to westerly mid/upper flow regime will persist
across the CONUS for much of the Day 4-8 period. Strong surface high
pressure also will dominate much of the forecast period, with
continental and offshore low-level trajectories maintaining a dearth
of boundary-layer moisture. Thunderstorm activity is expected to
remain low through the end of the period given a cold, dry, and
stable airmass.

..Leitman.. 01/10/2025

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ACUS48 KWNS 110853
SWOD48
SPC AC 110851

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0251 AM CST Sat Jan 11 2025

Valid 141200Z - 191200Z

...DISCUSSION...
Strong surface high pressure and a dry/stable airmass will envelop
much of the CONUS through Day 6/Thu. By the end of the period around
Day 7-8/Fri-Sat, medium range guidance indicates a shortwave upper
trough may move across the southern Plains and Southeast. As this
occurs, a deepening surface cyclone will develop over the southern
Plains and shift east. Strengthening southerly low-level flow ahead
of the surface low will allow for Gulf moisture to return northward
across portions of south/east Texas into the Gulf coast states. Some
severe thunderstorm potential could accompany this system at the end
of the forecast period. However, uncertainty and spread in forecast
guidance with regards to timing/track of the surface low, and
moisture return across the Gulf coast region, precludes severe
probabilities at this time.

..Leitman.. 01/11/2025

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ACUS48 KWNS 120854
SWOD48
SPC AC 120853

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0253 AM CST Sun Jan 12 2025

Valid 151200Z - 201200Z

...DISCUSSION...
Severe thunderstorm potential will remain low Days 4-5/Wed-Thu.
Surface high pressure over the Southeast, and a prior cold frontal
passage deep into the Gulf of Mexico will result in a dearth of
boundary-layer moisture, precluding thunderstorm activity.

Medium range guidance continues to indicate that thunderstorm
potential will increase sometime on Day 6/Fri, and into Days
7-8/Sat-Sun. While details remain uncertain, most guidance depicts
strong deep-layer southwesterly flow spreading from the southern
Plains into the Southeast and Ohio Valley as a series of embedded
shortwave troughs migrate through a broader upper trough across
central and eastern portions of the CONUS. Meanwhile, a surface low
is expected to deepen over the Plains on Day 6/Fri, allowing south/southeasterly low-level flow across the western Gulf to
transport modest moisture northward across the TX vicinity. As the
low progresses east/northeast through the end of the period,
boundary-layer moisture will increase ahead of a cold front across
the Southeast on Day 7/Sat. While surface low and upper trough
track/timing, and quality/extent of northward moisture return remain
uncertain, some increasing severe potential is possible Days
6-7/Fri-Sat across portions of east Texas into the Lower MS
Valley/Gulf Coast vicinity. Outlook probabilities may become
necessary in the next day or two if forecast confidence increases.

..Leitman.. 01/12/2025

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ACUS48 KWNS 130859
SWOD48
SPC AC 130858

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0258 AM CST Mon Jan 13 2025

Valid 161200Z - 211200Z

...DISCUSSION...
Shortwave upper ridging will move over the southern Plains vicinity
on Day 4/Thu as shortwave trough develops eastward over the
Southwest. While surface lee troughing will develop over the High
Plains as this occurs, high pressure will persist across eastern
portions of the Plains into the Southeast. This will keep Gulf
moisture offshore and thunderstorm potential is low on Day 4/Thu.

Forecast guidance continues to have quite a bit of spread heading
into the weekend (Days 5-6/Fri-Sat). In general, the Southwest upper
trough is expected migrate eastward into the southern Plains on
Friday, and across the Mid-South and Southeast on Saturday. However,
forecast guidance shows a fairly low-amplitude trough despite strong
mid/upper southwesterly flow streaming over the Plains into the
Southeast. A surface low should develop over the southern High
Plains and migrate east through weekend, allowing for northward
transport of Gulf moisture from east TX into the Lower MS Valley and central/eastern Gulf coast vicinity. Guidance varies quite a bit in
the northward extent of moisture return. The ECMWF suite of guidance
is a bit faster and further north compared to the GFS model suite.
Furthermore, SPC and NSSL machine learning guidance has trended
lower with severe potential compared to yesterday. While some severe
potential is possible from east TX into the central Gulf coast
Friday evening into Saturday, confidence remains too low to
delineate unconditional Slight risk probabilities at this time.

By Day 7/Sun, a cold front will move offshore the Atlantic coast and
deep into the Gulf of Mexico. Strong surface high pressure and an
arctic airmass will overspread much of the CONUS, bringing very
cold, dry/stable conditions into early next week.

..Leitman.. 01/13/2025

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ACUS48 KWNS 140857
SWOD48
SPC AC 140856

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0256 AM CST Tue Jan 14 2025

Valid 171200Z - 221200Z

...DISCUSSION...
Thunderstorm potential will increase on Day 4/Fri into Day 5/Sat
from roughly east Texas into the Lower MS Valley/central Gulf Coast
vicinity. An upper shortwave trough will develop eastward across the
southern Plains and Southeast during this time, before a deeper
large-scale trough quickly follows on its heels. A surface low will
deepen over OK/TX during the day Friday, arriving over the Lower MS
Valley by Day 5/Sat morning. Southerly low-level flow ahead of this
system will allow for northward transport of Gulf moisture across
east TX and the ArkLaTex vicinity. However, 60s F dewpoints are
expected to remain fairly far south across southeast TX into
southern LA through early Saturday. Furthermore, the timing of the
upper trough/surface low coincident with moisture return will occur
overnight. Forecast soundings show strong low-level inhibition, with
only weak elevated instability. While vertical shear will be strong,
supporting some potential storm organization, overall thermodynamic
profiles appear unlikely to support more than isolated strong
storms. Thunderstorm potential could shift east toward the central
Gulf coast on Day 5/Sat, but the upper trough is forecast to weaken
and higher-quality moisture will remain very near the coast. Similar
lackluster thermodynamic profiles as those expected on Day 4/Fri
indicate severe potential will likely remain limited.

Strong surface high pressure and an arctic airmass will settle
across much of the country during the second half of the forecast
period, ending thunderstorm potential through early next week.

..Leitman.. 01/14/2025

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ACUS48 KWNS 150903
SWOD48
SPC AC 150901

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0301 AM CST Wed Jan 15 2025

Valid 181200Z - 231200Z

...DISCUSSION...
A weak surface low and attendant cold front is forecast to sweep
across the Southeast on Day 4/Sat. Ahead of this feature, low-level
moisture will increase along the central and northeast Gulf coast
vicinity, with 60s F dewpoints generally remaining within the I-10
corridor. More modest moisture is possible across a broader area
from central MS/AL into GA. While mid/upper flow will be quite
strong, thermodynamics will largely limit a greater severe risk.
Nevertheless, isolated thunderstorms, and perhaps a couple of strong
storms, are possible near the immediate Gulf coast. Potential
remains too low however to include 15 percent probabilities at this
time.

By Day 5/Sun, the aforementioned cold front will move offshore.
Strong Arctic high pressure will build southeast and east across
much of the CONUS east of the Rockies through the end of the
forecast period, resulting in a cold, dry, and stable airmass.

..Leitman.. 01/15/2025

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ACUS48 KWNS 160906
SWOD48
SPC AC 160905

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0305 AM CST Thu Jan 16 2025

Valid 191200Z - 241200Z

...DISCUSSION...
A cold front will move offshore the Atlantic and Gulf coasts on Day
4/Sun. In the wake of the front, strong surface high pressure will
envelop most of the CONUS for much of the forecast period. This
Arctic airmass will bring below normal temperatures for a large part
of the country, resulting in dry/stable conditions and little
potential for thunderstorms.

..Leitman.. 01/16/2025

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ACUS48 KWNS 170944
SWOD48
SPC AC 170942

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0342 AM CST Fri Jan 17 2025

Valid 201200Z - 251200Z

...DISCUSSION...
Severe storms are not forecast through the Friday/D8 time frame,
with generally cool and stable conditions persisting.

The large longwave trough will shift east out of the central CONUS
especially on Tuesday D5, while additional waves or amplifications
are expected from the Rockies into the Plains again from Wed/D6 into
Friday/D8. Bouts of high pressure will be maintained over much of
the CONUS as a result of this pattern, with little to no chance of
appreciable low-level moisture return or destabilization over land.

..Jewell.. 01/17/2025

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ACUS48 KWNS 180835
SWOD48
SPC AC 180833

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0233 AM CST Sat Jan 18 2025

Valid 211200Z - 261200Z

...DISCUSSION...
The general pattern of a mid-upper trough over the central/eastern
CONUS will persist through much of the extended outlook period, with
the residual influence of an arctic air mass limiting buoyancy for
the vast majority of the CONUS. There may be some potential for
thunderstorms in the vicinity of south FL by early Wednesday (late
D4 into D5). However, forecast confidence in the sub-synoptic
details is low given a low-amplitude midlevel trough crossing the
northern Gulf of Mexico (with associated timing questions). The
residual arctic air mass and a probable lack of substantial surface cyclogenesis suggest that severe storms are unlikely.

..Thompson.. 01/18/2025

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ACUS48 KWNS 190844
SWOD48
SPC AC 190843

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0243 AM CST Sun Jan 19 2025

Valid 221200Z - 271200Z

...DISCUSSION...
A relatively stable period will persist through at least Friday/D6
as a large upper trough over the central and eastern CONUS
eventually exits the East Coast around Saturday/D7 morning. Behind
this large-scale feature, zonal flow may briefly develop before
another trough possibly develops to the west. Predictability is very
low for the latter part of the D4-8 period with large model spread,
and as such no severe areas are warranted.

..Jewell.. 01/19/2025

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ACUS48 KWNS 200944
SWOD48
SPC AC 200942

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0342 AM CST Mon Jan 20 2025

Valid 231200Z - 281200Z

...DISCUSSION...
For Thursday/D4 into Friday/D5, a large positive-tilt upper trough
will move from central parts of the CONUS toward the East Coast,
exiting land late Friday. Although strong winds aloft will
overspread the southeastern states, northerly winds are forecast to
hold over land.

Behind that system, high pressure will maintain stable conditions
over the eastern CONUS into Saturday/D6, although more of a zonal
flow regime is forecast thereafter. As a result of this possible
transition to the pattern, minimal low-level moisture return with
low 60s F dewpoints may return to parts of the TX Coast as surface
pressure lowers briefly.

Beyond the D6 time frame, model spread is large, but the general
signal is for the ongoing large trough pattern over the central and
eastern CONUS to at least shift northeastward into eastern Canada
and the northeastern states, allowing for gradual warming across the
South.

..Jewell.. 01/20/2025

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ACUS48 KWNS 210904
SWOD48
SPC AC 210902

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0302 AM CST Tue Jan 21 2025

Valid 241200Z - 291200Z

...DISCUSSION...
An amplified and progressive upper trough will move quickly from the
MS Valley to the East Coast on Friday/D4, with zonal flow developing
behind this system. High pressure will follow, maintaining dry
offshore winds across the Southeast.

Models remain in relatively good agreement with the large-scale
pattern through the weekend, depicting a positive-tilt upper trough
over the southwestern states. A broad fetch of west/southwest flow
aloft is forecast to extend across the southern Plains and into much
of the East, with the deep upper low over eastern Canada. Sufficient instability is forecast to develop across parts of southern and
eastern TX into the lower MS Valley Saturday/D5 Night into
Sunday/D6. Given the antecedent cool air at the surface, substantial
clouds and precipitation appear likely, reducing overall
destabilization and severe potential.

Models diverge around Monday/D7, with uncertainly regarding whether
another wave will develop into the northern Plains and Great Lakes
as disturbances rotate around the large-scale low. To the west, the
trough/low over the Southwest may eventually eject east, but timing
for this is uncertain as well with low predictability at this time
frame. In any case, severe potential is forecast to be low through
the period.

..Jewell.. 01/21/2025

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ACUS48 KWNS 220732
SWOD48
SPC AC 220730

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0130 AM CST Wed Jan 22 2025

Valid 251200Z - 301200Z

...DISCUSSION...
On Saturday/D4, an upper trough will be exiting the Northeast early,
with temporary zonal flow across much of the central and eastern
states. The large-scale upper low by this time will be located
around Hudson Bay, with a low-amplitude feature possibly rotating
eastward across the Great Lakes. To the west, an upper trough and/or
cut-off low will drift southward across CA and NV, as upper ridging
develops north of there across southern BC and the Pacific NW. High
pressure will remain over the eastern states, providing dry and
stable conditions.

By Sunday/D5, southerly low-level winds across TX and into the lower
MS Valley will allow for at least elevated instability to develop,
and this should favor general thunderstorms from eastern TX to the
MS River. Given the weak instability and likelihood of substantial
clouds and precipitation, severe weather seems unlikely.

This glancing low-level warm/moist advection regime will remain in
place into Monday/D6, with additional precipitation likely across
parts of the Gulf Coast states. Relatively cool boundary-layer
conditions and marginal instability should preclude any severe
changes.

For the Tuesday/D7 time frame and beyond, the upper trough over the
Southwest will eventually proceed east toward the southern Plains,
but predictability is low regarding the timing of this feature.

..Jewell.. 01/22/2025

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ACUS48 KWNS 230818
SWOD48
SPC AC 230817

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0217 AM CST Thu Jan 23 2025

Valid 261200Z - 311200Z

...DISCUSSION...
A large upper trough will remain over eastern Canada for much of the
Day 4-8 period, with the southern extent of the colder air aloft
affecting the area from the Great Lakes into the Northeast. Detached
from this feature will be a lower-latitude upper low which is
forecast to drop south across CA on Sunday/D4, and pivot east into
AZ through Monday/D5. For the following days through Thursday/D8,
this low will gradually shift east toward the southern Plains.
However, predictability is low for such a slow-moving feature cut
off from the primary storm track to the north.

Given this pattern, little in the way of a focus will be present for
any severe weather potential until perhaps very late in the period,
Thursday/D8 or beyond. Prior to the southwest-US upper low moving
into the Plains, a general east-west oriented boundary will exist
along the Gulf Coast states, with modest low-level warm advection
resulting in scattered showers and thunderstorms, primarily over
parts of Texas.

..Jewell.. 01/23/2025

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ACUS48 KWNS 241001
SWOD48
SPC AC 240959

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0359 AM CST Fri Jan 24 2025

Valid 271200Z - 011200Z

...DISCUSSION...
On Monday/Day 4, a shortwave ridge is forecast over the
south-central U.S. The overall pattern is forecast to gradually
amplify on Tuesday/Day 5 and Wednesday/Day 6, as a mid-level low
moves slowly eastward across the Desert Southwest. Ahead of the
system, moisture return is expected across the southern Plains in
the early to mid week, as mid-level flow becomes southwesterly. A
moist airmass is forecast to become established across the southern
Plains by Wednesday, with scattered thunderstorms likely to develop
in the afternoon and evening across parts of Texas and Oklahoma. The
potential for convective development is expected to continue into
Thursday/Day 7 and Thursday night as the mid-level system approaches
and moves into the southern Plains. At this time, model forecasts
suggest that instability, lift and deep-layer shear could support an
isolated severe threat in parts of Texas and possibly southern
Oklahoma, from Wednesday evening into Thursday. However, there is
still substantial variance among solutions concerning this system,
and confidence is low concerning magnitude and spacing. At this
time, it appears the overall severe threat will remain marginal. On
Friday/Day 8, the potential for convection is forecast to move
eastward into parts of the Southeast, where little instability is
forecast.

..Broyles.. 01/24/2025

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ACUS48 KWNS 250956
SWOD48
SPC AC 250954

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0354 AM CST Sat Jan 25 2025

Valid 281200Z - 021200Z

...DISCUSSION...
On Tuesday/Day 4, a mid-level low will likely be in the Desert
Southwest. This low is forecast to move southward into northwest
Mexico on Wednesday/Day 5, and then eject eastward across the
southern Plains from Thursday/Day 6 into Friday/Day 7. This system
is forecast to reach the Mississippi Valley late Friday night into
early Saturday/Day 8. Ahead of the system, low-level moisture is
forecast to return northward into parts of southern and central
Texas, where surface dewpoints could reach the 60s F. The models
suggest that destabilization will remain rather weak as the system
approaches Thursday evening. However, strong lift and deep-layer
shear could be enough for organized convection Thursday evening into
Thursday night over parts of south and central Texas. The main
uncertainty is instability, with the models currently having a wide
variance of solutions. The timing of the system is also
questionable, which is forecast to move into the southern Plains
early in the day on Friday. Due to the uncertainties, will not add a
severe threat area at this time.

..Broyles.. 01/25/2025

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ACUS48 KWNS 261001
SWOD48
SPC AC 260959

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0359 AM CST Sun Jan 26 2025

Valid 291200Z - 031200Z

...DISCUSSION...
...Wednesday/Day 4 to Thursday/Day 5...
A mid-level low is forecast to move eastward across the Desert
Southwest from Wednesday/Day 4 into Thursday/Day 5. Low-level
moisture advection will take place ahead of the system across the
southern Plains on Wednesday into Wednesday night, with surface
dewpoints increasing into the 60s F across parts of the southern
Plains. Scattered to numerous thunderstorms appear likely to develop
across the western part of the moist sector Wednesday night across
much of central and northern Texas, as large-scale ascent increases
ahead of the approaching system. This, combined with increasing
instability, and strong deep-layer shear along the western edge of
the moist sector should result in a severe threat late Wednesday
night. A cluster of strong and potentially severe storms may develop
in west-central Texas, with the severe threat persisting into
Thursday, as an MCS moves eastward across the southern Plains.
Supercells with isolated large hail and wind damage will be
possible. There is some concern that moisture return could be slower
than forecast. However, the strength of the system could help to
overcome instability concerns, and it appears a severe threat will
be possible as the mid-level jet ejects northeastward into the
southern Plains from Wednesday night into Thursday.

...Friday/Day 6 and Sunday/Day 8...
The mid-level trough is forecast to move across the southern Plains
on Friday/Day 6, as a cold front advances eastward into the lower
Mississippi Valley. On Saturday/Day 7 and Sunday/Day 8, this front
is forecast to move across the eastern U.S. Although thunderstorms
will be possible along and ahead of the front, instability is
forecast to be very weak suggesting a severe threat will be
unlikely.

..Broyles.. 01/26/2025

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ACUS48 KWNS 270954
SWOD48
SPC AC 270953

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0353 AM CST Mon Jan 27 2025

Valid 301200Z - 041200Z

...DISCUSSION...
...Thursday/Day 4 and Friday/Day 5...
A mid-level low is forecast to move into the southern High Plains on Thursday/Day 4, as an associated jet streak moves across Texas.
Widespread convection appears likely to be ongoing at the start of
the period, related to an MCS along the western edge of the moist
sector. It appears the MCS will move into central and northeast
Texas during the afternoon, where surface dewpoints should be in the
60s F. This moist and unstable airmass will make strong to severe
thunderstorms be possible in the afternoon as the mid-level jet
ejects northeastward across the region. Supercells with isolated
large hail and severe gusts will be possible.

The mid-level system is forecast to move across the Ark-La-Tex on
Friday/Day 5, as a cold front advances eastward into the central
Gulf Coast states. Thunderstorms will be possible along and ahead of
the front during the day, and a marginal severe threat may develop
near the central Gulf Coast.

...Saturday/Day 6 to Monday/Day 8...
The cold front is forecast to move quickly eastward into the
Atlantic by Saturday as surface high pressure settles over the
eastern U.S. A west-northwest flow mid-level pattern is forecast in
the central and eastern U.S. on Sunday/Day 7 and Monday/Day 8. This
could help to limit moisture return, keeping the chance for
thunderstorms low across the continental U.S.

..Broyles.. 01/27/2025

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ACUS48 KWNS 280932
SWOD48
SPC AC 280931

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0331 AM CST Tue Jan 28 2025

Valid 311200Z - 051200Z

...DISCUSSION...
Models forecast steady eastward progression of a cold front across
the Southeast and Mid-Atlantic region Day 4/Friday, as a mid-level
low devolves into a fast-moving open wave that is expected to cross
the Appalachians Friday night, exiting the East Coast states prior
to the start of the Day 5 period.

While non-zero severe potential will likely exist ahead of the cold
front across southern portions of the central Gulf Coast states, it
appears at this time that instability will remain meager at best,
limiting overall severe potential.

After the front moves offshore, lingering only across the Florida
Peninsula Day 5/Saturday, severe weather is not expected.

Models begin to diverge Day 6/Sunday, with the GFS maintaining a
low-amplitude, quasi-zonal flow regime through much of the remainder
of the period. While the ECMWF undergoes a gradual trend of
slightly greater amplification toward more pronounced eastern U.S.
troughing and central U.S. ridging, prevalence of surface high
pressure/cold continental air east of the Rockies precludes severe
potential through the end of the period.

..Goss.. 01/28/2025

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ACUS48 KWNS 290958
SWOD48
SPC AC 290957

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0357 AM CST Wed Jan 29 2025

Valid 011200Z - 061200Z

...DISCUSSION...
As a short-wave trough continues shifting away from the U.S./across
the western Atlantic early in the period, flow aloft across the U.S.
is progged by medium-range models to gradually trend toward a more
zonal configuration.

A trough/low is forecast to shift eastward out of the Canadian
Rockies and across the Prairie Provinces days 4-5 (this weekend),
and then eastward across Ontario, Quebec, and eventually the
Maritime Provinces days 5-7 (early next week).

In tandem, an associated/deepening surface low will likewise shift
gradually eastward across southern Canada. As this occurs, an
Arctic cold front will evolve, shifting eastward across the Great
Lakes and then the Northeast, while the trailing portion of the
boundary sags southward in a more west-to-east orientation, roughly
paralleling the zonal flow aloft prevailing by this time over the
CONUS.

With the zonal flow, and sagging west-to-east front, severe-weather
potential appears likely to remain low through the period. While
some convection will be possible near/south of the sagging front,
minimal northward advection of low-level moisture and weak lapse
rates suggest lack of appreciable instability, which it appears at
this time should hinder more robust convection through the period.

..Goss.. 01/29/2025

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ACUS48 KWNS 300908
SWOD48
SPC AC 300906

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0306 AM CST Thu Jan 30 2025

Valid 021200Z - 071200Z

...DISCUSSION...
Medium-range models are in reasonably good agreement into Day 6,
with some differences emerging at that point -- and continuing
through the end of the period -- with respect to progression of
small-scale, short-wave troughing moving through the prevailing
westerlies aloft.

During the days 4-5 time frame (Sunday and Monday), upper short-wave
troughing is forecast to move across southern Canada and the Great
Lakes region, and eventually the Ottawa and St. Lawrence Valleys and
into the Canadian Maritimes. As this occurs, and an associated
surface low likewise shifts eastward, a cold front will progress
eastward across the Northeast, while sagging southward across the
central Plains/Midwest. The front will eventually decelerate into
the southern Plains and Southeast states by Day 6 (Tuesday).

Through Day 5, severe weather is not expected. Day 6, potential for
elevated convection -- north of the aforementioned baroclinic zone
-- will become possible, modulated by the passage of disturbances
embedded in the upper westerlies. While models differ on timing and
intensity of these disturbances, it is conceivable that marginal
hail potential could occur at some point through latter stages of
the period. At this time, risk appears low, and too uncertain to
highlight given the subtle/weak nature of the features embedded in
the background low-amplitude flow field.

..Goss.. 01/30/2025

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ACUS48 KWNS 311007
SWOD48
SPC AC 311005

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0405 AM CST Fri Jan 31 2025

Valid 031200Z - 081200Z

...DISCUSSION...
A generally low-amplitude upper pattern, characterized by fast
westerly flow aloft, is expected to prevail through the medium-range
period. Global models are in reasonably good agreement with most of
the synoptic-scale details into day 6 (Wednesday), after which
differences become increasingly apparent.

Days 4-5, the generally zonal flow pattern will persist, though some
minor amplification of troughing over the West is expected Day 5, as
the western Canada low drifts southward toward/into the Pacific
Northwest. A rather subtle, lead shortwave trough is forecast to
shift across southern California into the Desert Southwest late day
5 (Tuesday), and into the central Plains through the first half of
day 6. An associated, central Plains surface low is forecast to
evolve, with a cold front shifting out of the southern Rockies
toward the southern Plains. With favorably strong flow aloft, any
elevated destabilization sufficient to support convective
development may result in some potential for hail across central
portions of the country. At this time, however, expectations for
weak instability overall, and likelihood that the boundary layer
remains stable, should preclude appreciable surface based
thunderstorm potential. In any case, any potential for severe
weather appears too low to warrant areal inclusion at this time.

The surface front should continue eastward/southeastward across the
U.S. days 6-7, but even weaker instability expected ahead of the
boundary should preclude any appreciable severe weather potential.

..Goss.. 01/31/2025

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ACUS48 KWNS 311011
SWOD48
SPC AC 311009

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0409 AM CST Fri Jan 31 2025

Valid 031200Z - 081200Z

...DISCUSSION...
A generally low-amplitude upper pattern, characterized by fast
westerly flow aloft, is expected to prevail through the medium-range
period. Global models are in reasonably good agreement with most of
the synoptic-scale details into day 6 (Wednesday), after which
differences become increasingly apparent.

Days 4-5, the generally zonal flow pattern will persist, though some
minor amplification of troughing over the West is expected Day 5, as
the western Canada low drifts southward toward/into the Pacific
Northwest. A rather subtle, lead shortwave trough is forecast to
shift across southern California into the Desert Southwest late day
5 (Tuesday), and into the central Plains through the first half of
day 6. An associated, central Plains surface low is forecast to
evolve, with a cold front shifting out of the southern Rockies
toward the southern Plains. With favorably strong flow aloft, any
elevated destabilization sufficient to support convective
development may result in some potential for hail across central
portions of the country. At this time, however, expectations for
weak instability overall, and likelihood that the boundary layer
remains stable, should preclude appreciable surface based
thunderstorm potential. In any case, any potential for severe
weather appears too low to warrant areal inclusion at this time.

The surface front should continue eastward/southeastward across the
U.S. days 6-7, but even weaker instability expected ahead of the
boundary should preclude any appreciable severe weather potential.

..Goss.. 01/31/2025

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ACUS48 KWNS 011001
SWOD48
SPC AC 010959

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0359 AM CST Sat Feb 01 2025

Valid 041200Z - 091200Z

...DISCUSSION...
Medium-range models continue to depict generally zonal flow across
the U.S. through the medium-range period. By the start of the
period, a prominent baroclinic zone at the leading edge of an Arctic
airmass is progged to have become established in a roughly
west-to-east manner from the Mid-Atlantic region west-southwestward
into the southern Plains. Weak/subtle perturbations forecast to
move across the U.S. within the background/fast westerly flow regime
are expected to modulate the north-south position of this boundary,
but with its average location remaining roughly unchanged through
day 6 -- after which evolving model differences cast more
substantial uncertainty into the forecast.

At this time, it appears that mainly elevated convection -- and
perhaps a limited potential for hail -- may evolve primarily north
of the front, in the late day 4 to early day 6 time frame, from the
central U.S. eastward into the Tennessee Valley/Mid South region.
However, at this time, risk appears to limited/low to highlight with
a 15% probability area.

..Goss.. 02/01/2025

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ACUS48 KWNS 020953
SWOD48
SPC AC 020951

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0351 AM CST Sun Feb 02 2025

Valid 051200Z - 101200Z

...DISCUSSION...
Uncertainty remains high in the medium-range period, in terms of
both pattern evolution, and attendant potential for severe weather.
Models agree in general that early in the period, a quasi-zonal
pattern aloft will prevail across the U.S., and a roughly
west-to-east surface baroclinic zone will be in place from the
central/southern Plains vicinity eastward to the Carolinas.

Initially, any convective potential should remain limited, and
largely confined to the cool side of the surface front. However,
emerging model differences become evident, even early in the period,
in terms of the eastward advance of various short-wave disturbances
through the background westerlies. This progression of short-wave
energy -- varying in degree from model to model -- results in
correspondingly varying degrees of amplification of the flow field
aloft, and also correspondingly, varying levels of mass response at
the surface.

Within the generally more amplified ECMWF, even early in the period
but particularly through the middle and later stages of the
forecast, likelihood for greater northward transport of higher
theta-e air would exist, meaning greater potential for
destabilization, and -- given flow aloft more than sufficient for
organized convection -- greater potential for severe weather.

With all of that said, given what appears to be a pattern of
inherently low predictability, delineating areas of severe-weather
potential would appear imprudent at this time, at the medium-range
time frames.

..Goss.. 02/02/2025

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ACUS48 KWNS 031004
SWOD48
SPC AC 031003

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0403 AM CST Mon Feb 03 2025

Valid 061200Z - 111200Z

...DISCUSSION...
A short-wave trough is progged to be moving across the Midwest/Ohio
Valley day 4 (Thursday), along with a weak surface wave moving along
a baroclinic zone separating Arctic air to the north, and a more temperate/modifying continental airmass to the south. Late day 4
(Friday morning), the low is forecast to undergo significant
cyclogenesis over the Canadian Maritimes, with the trailing surface
front becoming realigned in an east/west orientation from the
Carolinas to the southern Plains.

During the day 4 period, as the cold front progresses southward
across the Mid South in the immediate wake of the weak frontal wave,
showers and isolated thunderstorms -- initially confined to the cool
side of the front -- will likely develop across the Mid South in a
weakly destabilizing warm sector. With strong/weakly veering flow
through the lower troposphere, storms which do develop would be
fast-moving, and could intensify locally to near severe levels.
However, current expectations are that the degree of surface-based destabilization will be limited, and thus overall severe potential
tempered as well. While low-probability severe risk across parts of
the Mid South may be required in later outlooks, the risk appears
too low to highlight at this time.

Day 5, the next short-wave trough is forecast to be crossing the
Rockies, and will likely begin impinging on the Plains overnight.
This will support new frontal low development along the pre-existing west-to-east baroclinic zone. At this time, projections are that a
developing low may exist over the Ozarks vicinity, but with limited
CAPE expected in the evolving warm sector, severe weather potential
would appear minimal at best.

Day 6, the low is forecast to move rapidly east-northeastward across
the Ohio Valley through the day, and then on into/across New England
overnight. As this occurs, the trailing portion of the baroclinic
zone should surge southeastward with time -- reaching a position
from the Mid-Atlantic region to the Gulf Coast States late. Once
again, showers and a few thunderstorms will likely occur within the
warm sector, but again, limited CAPE should continue to characterize
the pre-frontal environment, tempering overall risk for severe
weather.

The front should be continuing southward Day 7, moving off the Gulf
Coast during the period. Limited CAPE and weaker flow with
southward extent should continue to limit any severe risk,
continuing through day 8 as the front shifts across Florida through
the end of the period.

..Goss.. 02/03/2025

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ACUS48 KWNS 050937
SWOD48
SPC AC 050936

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0336 AM CST Wed Feb 05 2025

Valid 081200Z - 131200Z

...DISCUSSION...
Medium-range global models appear to be in reasonable large-scale
agreement into the first half of day 6 (Monday). At this point,
more substantial differences begin to emerge with respect to the
amplification of the flow field across the U.S., as the main western
U.S. trough begins a slow eastward advance. These differences are
significant in that speed and timing of the advance of this system
will influence surface cyclogenesis along what has been a
persistent, roughly west-to-east baroclinic zone across the
south-central and southeastern CONUS. Stronger/inland low
development along this front would potential bring an increase in severe-weather potential, but this scenario is far too uncertain at
this point to highlight through the second half of the period.

Earlier in the period, a frontal low along the surface baroclinic
zone is forecast to shift out of the Oklahoma vicinity, and
east-northeastward across the Ohio Valley area day 4, before
reaching the southern New England coastal vicinity by the start of
day 5. However, very weak warm-sector instability is expected at
this time, which should preclude severe risk. As the low deepens
northward into the Canadian Maritimes, the trailing cold front
should settle back into its recently persistent position from the
southern Plains to the Southeast, and remain there into the Day 6
period ahead of the advancing western upper trough. Again, with
weak instability near the boundary and southward into the warm
sector, severe weather is not expected.

..Goss.. 02/05/2025

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ACUS48 KWNS 060957
SWOD48
SPC AC 060956

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0356 AM CST Thu Feb 06 2025

Valid 091200Z - 141200Z

...DISCUSSION...
The zonal flow aloft which has persisted over the U.S. recently --
and into the start of the medium-range period -- is progged to
gradually amplify, with flow becoming more cyclonic with time across
the U.S. through the period. The initial effect of this gradual
upper flow field evolution will be to gradually suppress the
persistent west-to-east surface front over the U.S. southward.
Through day 5 (Monday), this front should extend from Texas eastward
through the Gulf Coast States to Georgia/South Carolina. Severe
weather is not expected, as this front drifts southward and settles
across this area.

Through the second half of the period (late day 6 onward),
disturbances moving across the southern U.S. within increasingly
cyclonic flow aloft will influence potential for surface wave
development along the front. Any appreciable cyclogenesis could
result in northward transport of higher theta-e Gulf air, and thus
some destabilization ahead of the low. With strong flow aloft atop
the surface front, this would suggest an environment that would
support severe-weather potential.

With that said, while a general/overall increase in severe-weather probabilities over the Gulf Coast region is becoming evident during
the second half of the period, uncertainty remains high. Timing and
degree of any such risk will depend upon subtle features aloft, and
their effects on surface mass response. And given predictability
issues with respect to timing an intensity of such subtle features,
it appears premature at this time to introduce 15% risk areas in the
day 7 to 8 time frame.

..Goss.. 02/06/2025

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ACUS48 KWNS 041001
SWOD48
SPC AC 040959

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0359 AM CST Tue Feb 04 2025

Valid 071200Z - 121200Z

...DISCUSSION...
Medium-range models are in reasonably good agreement through day 6
(Sunday), in terms of large-scale features. Substantial divergence
begins thereafter, casting substantial uncertainty into the forecast
beyond the upcoming weekend.

Day 4, as an upper short-wave trough crossing the Northeast moves
into/across the Canadian Maritimes, the quasi-zonal flow pattern
over the U.S. will continue. Weak amplification of the flow will
occur over the West with time, however, as a short-wave trough moves
across the Rockies. As this occurs, frontal low development is
expected along the persistent west-to-east front lying from the
southern Plains to the Mid-Atlantic region. However, with only weak instability expected near the developing low, and eastward along the
front, convection is forecast to remain disorganized.

Day 5, the upper wave is forecast to continue eastward across the
central and northern Plains through the day, and into and across the
Great Lakes region overnight. The associated frontal low --
initially progged to lie over the Oklahoma vicinity, will deepen as
it shifts east-northeastward with time, reaching the northeast
through the end of the period. The trailing surface front will
sharpen and advance southeastward, extending from the Mid-Atlantic
region southwestward to coastal Texas late. While showers and a few thunderstorms will be associated with the frontal advance, weak
instability anticipated at this time should again hinder convective
intensity.

Day 6, as the low moves offshore and the front continues advancing
steadily southeastward, it should clear the Atlantic and Gulf Coasts
during the evening, lingering only across Florida through the end of
the period. The continued trend of weak instability, as well as
weakening flow with southward extent, should hinder prospects for
more robust convection.

..Goss.. 02/04/2025

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ACUS48 KWNS 100939
SWOD48
SPC AC 100937

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0337 AM CST Mon Feb 10 2025

Valid 131200Z - 181200Z

...DISCUSSION...
There appears to be severe potential along parts of the East Coast
as the initial trough moves offshore on Thursday. In advance of the
next trough, initial moisture return into the lower Mississippi
Valley region could promote some severe potential late Friday.
Uncertainty in the environment/forcing precludes highlights both
days. Severe weather potential increases further on Saturday in the
Southeast and may linger into Sunday along the East Coast. For
Monday, broad surface high pressure and cold air east of the Divide
will minimize severe risk.

...Southeast...
There has been a consistent signal for a potent upper-level trough
to move into the West Coast on Friday. In response to this trough, a
deep surface low is expected to develop in eastern Colorado and move
into Oklahoma. These features will promote strong moisture return
into parts of the central Gulf Coast states late Friday into
Saturday. Appreciable moisture return may reach into the Mid-South.
This setup would favor scattered to numerous severe storms from the
Sabine Valley vicinity into much of Mississippi/Alabama. Both
low-level and deep-layer shear would be strong in this regime. The
surging cold front will likely be the primary focus for storms, but
the strong synoptic forcing within a potentially weakly capped
boundary-layer could also bring about more discrete storms ahead of
the line as well. The primary uncertainties will be the
timing/amplitude of the trough as well northward/eastward extent of
sufficient buoyancy. With the consistent signal in deterministic and
ML guidance, 15% severe probabilities appear warranted for Saturday.
Refinement of the highlighted area is probable as additional data
becomes available.

...Carolinas into Mid-Atlantic...
As the strong trough, surface low, and cold front continue east on
Sunday, there will be some potential for additional severe storms
from the Mid-Atlantic in to portions of the Carolinas. It is not
clear if the timing of these features will be well phased with the
diurnal cycle. Trends in guidance will continue to be monitored.

..Wendt.. 02/10/2025

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ACUS48 KWNS 140852
SWOD48
SPC AC 140851

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0251 AM CST Fri Feb 14 2025

Valid 171200Z - 221200Z

...DISCUSSION...
Strong surface high pressure is forecast to extend from the northern Rockies/Plains through much of the Midwest on Day 4/Mon. A prior
cold frontal passage into the Atlantic and Gulf waters will leave a
dearth of boundary-layer moisture east of the Rockies. An upper
trough will deepen on Day 5/Tue, moving from the Southwest and Great
Basin to the Atlantic coast by Day 8/Fri. A weak surface low may
develop across Texas on Day 5/Tue ahead of the upper trough,
allowing some moisture return across southeast TX. Some thunderstorm
activity is possible ahead of a strong Arctic cold front, but severe
potential appears limited. The Arctic front will continue to
progress eastward, moving offshore the Gulf coast by Day 7/Thu
morning. A very cold and dry airmass in the wake of this system will
preclude thunderstorm potential across the CONUS late in the
forecast period.

..Leitman.. 02/14/2025

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ACUS48 KWNS 090956
SWOD48
SPC AC 090954

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0354 AM CST Sun Feb 09 2025

Valid 121200Z - 171200Z

...DISCUSSION...
...Sabine Valley into Lower Mississippi Valley Vicinity...
Precipitation appears likely to be ongoing within the warm advection
zone near the cold front on Wednesday. The primary shortwave
perturbation within the broader cyclonic flow aloft is expected to
move from the southern Plains into the mid-Mississippi Valley by the
afternoon. A weak surface wave will develop along the front and
quickly move northeast. This overall pattern will not favor
significant northward progression of Gulf moisture. With deep-layer
shear remaining parallel to the boundary, a broad warm advection
regime, and stronger ascent displaced northward, confidence in more
than isolated disorganized severe storms is low.

The intrusion of cold air into the Gulf on Friday is expected to be
greater than earlier in the week. Portions of the northern Gulf are
likely to be impacted with some potential the cold air to reach the
central Gulf. By Friday afternoon, the next upper-level trough is
forecast to reach the Southwest with a lee cyclone developing in
eastern Colorado. With the low deepening as it moves into the
Mid-South, rapid northward moisture return is possible within the
region through the day Saturday. This pattern would support severe
storms. Model guidance has had some consistency with the broad
pattern evolution, but has continued to differ run to run with
timing and intensity of key features. Further, given the colder air
that will be in place prior to any moisture return, the overall
quality of the airmass ahead of the upper trough is also not
certain. Trends in guidance will continue to be monitored for this
coming Saturday.

...Portions of the Southeast...
As the surface low moves northeast, it is expected to deepen as it
moves into the southern/central Appalachians on Thursday. This will
push the cold front into Georgia and the Carolinas. A narrow
warm-sector ahead of the front may destabilize enough for isolated
strong to severe storms, but confidence in more widespread activity
is low given the uncertain buoyancy and the increasingly
northward-displace mid-level ascent.

On Sunday, based on current guidance, a similar scenario to Thursday
will occur. However, the trough/surface low are forecast to be
stronger and there is greater potential for a larger warm sector.
Uncertainty remains high this far in advance, however.

..Wendt.. 02/09/2025

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ACUS48 KWNS 070949
SWOD48
SPC AC 070947

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0347 AM CST Fri Feb 07 2025

Valid 101200Z - 151200Z

...DISCUSSION...
Fairly zonal flow across the CONUS will evolve into broadly cyclonic
flow as a western trough begins to amplify by the middle of next
week. This trough will be the focus of severe weather potential from
the Sabine Valley into the central Gulf Coast region by late in the
week. Another western trough is forecast by late next week.
Uncertainty in the timing and evolution of these features is high,
however.

...Central Gulf Coast Vicinity...
Model variability remains rather high for the Tuesday through
Thursday period. While there is general consensus between the
GFS/ECMWF that a western upper trough will be amplifying, the
shortwave trough that ultimately ejects into the southern Plains is
out of phase between the two models--the ECMWF being the more progressive/intense of the two. These differences lead to timing and
magnitude variability of the surface low and northward advancement
of Gulf moisture. Pattern-wise, upper 60s to low 70s F dewpoints
currently reside in the Gulf and the upcoming cold front this
Sunday/Monday is not expected to push that moisture south. Some
increase in severe potential would be expected as the upper trough
approaches. At present, model and ML guidance would suggest the
greatest severe potential would exist on Wednesday or Thursday
depending on the timing/evolution of the upper wave. Confidence
remains too low for severe probabilities, but model trends will
continue to be monitored.

By next Friday, models are currently in agreement that another
western trough will amplify. Even with this consistency, the frontal
intrusion into the Gulf prior to this secondary trough casts doubt
on the quality of moisture return this far in advance. Uncertainty
is too high for highlights.

..Wendt.. 02/07/2025

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ACUS48 KWNS 080948
SWOD48
SPC AC 080946

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0346 AM CST Sat Feb 08 2025

Valid 111200Z - 161200Z

...DISCUSSION...
Severe weather potential is expected to increase by the middle of
next week. As the upper trough ejects into the southern/central
Plains, moisture that is expected to remain just off the Gulf coast
will advect northward Tuesday/Wednesday. At least isolated severe
storms could occur from the Sabine Valley into portions of the Lower Mississippi Valley on Wednesday. Early-day precipitation, stronger
forcing displaced to the north, and upper-level winds roughly
parallel to the surface boundary reduce confidence in more
widespread severe storms. On Thursday, the front will push into the
Southeast. Upper-level flow will remain strong over the region, but
the mid-level ascent and surface cyclone will move farther north and
the warm sector will likely be narrow.

By late next week, the cold front is forecast to stall near the Gulf
Coast. Another slightly more amplified upper trough will move
eastward into the weekend. Depending on the degree of cold air
intrusion into the Gulf Thursday/Friday and the strength of the
trough/surface cyclone, more robust moisture return will be possible
during the weekend. Uncertainty remains high at this juncture as
models have not been overly consistent with this signal in the past
1-2 days of runs. Trends will continue to be monitored.

..Wendt.. 02/08/2025

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ACUS48 KWNS 110939
SWOD48
SPC AC 110938

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0338 AM CST Tue Feb 11 2025

Valid 141200Z - 191200Z

...DISCUSSION...
...Day 4/Friday...
Late in the period, the approaching trough will promote moisture
return within the Lower Mississippi Valley, Arkansas, and East
Texas. Model guidance shows some hints at potential storm
development, but coverage is far from certain due to some lingering
capping from warmer air aloft. Should storms form, they most likely
would be elevated. Coverage concerns preclude adding severe
probabilities, but large hail is conditionally possible.

...Day 5/Saturday...
A strong trough, which has trended more amplified in the ECMWF, is
expected to impact the Sabine Valley into the Southeast starting in
the afternoon. The latest model trends also have a more favorable
placement of the surface low in the Tennessee Valley. These factors
will drive strong moisture advection into the region by Saturday
morning, continuing into Sunday. Intense wind fields throughout the
column will support organized storms capable of all hazards.
Damaging winds, particularly with linear convection along the strong
cold front, currently appears as the main threat. The magnitude of
the tornado threat will largely depend on discrete development ahead
of the front. Given the moist environment with minimal inhibition
and strong forcing, that scenario is certainly plausible. Discrete
development or not, low-level wind fields still will support
line-embedded circulations. Despite more limited buoyancy farther
north, the strongly forced convective line and 60-70 kts of 850 mb
flow would support damaging winds even in shallow convection.
Uncertainties still remain along the fringes of the highlighted area
(i.e., how far west will convection form, how unstable will it be to
the north/east). Mid-level lapse rates will also not be overlay
steep. Even so, the overall pattern continues to support the
potential for scattered to numerous severe storms.

...Day 6/Sunday...
As the strong trough and cold front continue east, the convective
line will likely stretch from the eastern Florida Panhandle into the
Piedmont early Sunday morning. Strong forcing and wind fields will
still be in place. The primary uncertainty is the degree of
destabilization that can occur ahead of the line given the arrival
before the diurnal heating maximum. Where heating can occur, which
may be near the coastline, some severe potential will exist. The
intensity and coverage of these storms is enough in question that
severe probabilities will be withheld.

...Day 7 Onward...
Severe potential should be minimal on Monday given the expansive
colder air and surface high pressure. Another shortwave trough will
approach the southern Plains on Tuesday. While some moisture return
is possible, this will occur after a fairly substantial cold air
intrusion to the central Gulf. Uncertainty in an appreciable severe
risk is high.

..Wendt.. 02/11/2025

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