ACUS48 KWNS 050909
SWOD48
SPC AC 050908

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0308 AM CST Fri Dec 05 2025

Valid 081200Z - 131200Z

...DISCUSSION...
Medium-range guidance indicates that at least modestly amplified
mid/upper ridging will continue to build and be maintained across
the Pacific coast into the Rockies through next week. Within the
northwesterly flow downstream of this feature, several digging short
wave perturbations appear likely to reinforce large-scale troughing
across the eastern U.S., while also contributing to occasional
surface cyclogenesis from the lee of the northern Rockies through
the northern and middle Atlantic Seaboard. However, these are not
likely to be accompanied by a strengthening southerly return flow
emanating from the Gulf Basin. Regardless, in the wake of a
reinforcing cold intrusion across much of the Florida Peninsula, and
through much of the Gulf Basin, early next week, it appears that
boundary-layer modification over the Gulf will not become conducive
to appreciable inland low-level moisture return.

..Kerr.. 12/05/2025

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ACUS48 KWNS 060907
SWOD48
SPC AC 060905

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0305 AM CST Sat Dec 06 2025

Valid 091200Z - 141200Z

...DISCUSSION...
Downstream of an increasingly prominent blocking high evolving near
and to the north of the Aleutians, it appears that the large-scale
mid/upper flow pattern may not appreciably change, aside from
perhaps some amplification, across North America into next weekend.
Models indicate that large-scale mid/upper ridging will generally be
maintained across the Pacific Coast through Rockies, with downstream
troughing across the Mississippi Valley into western Atlantic.

Short wave developments within this regime are forecast to lead to
another notable intrusion of cold/dry air to the lee of the Rockies,
through much of the Southeast and Gulf Basin, late this coming week
into next weekend. It appears that this will occur before Gulf
boundary-layer modification, in the wake of the prior cold/dry
intrusion, can become potentially supportive of a substantive moist
return flow.

..Kerr.. 12/06/2025

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ACUS48 KWNS 070850
SWOD48
SPC AC 070848

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0248 AM CST Sun Dec 07 2025

Valid 101200Z - 151200Z

...DISCUSSION...
After becoming suppressed a bit, medium-range guidance indicates
that a blocking high may become more prominent again, near/north of
the Aleutians late this coming work week into next weekend.
Surrounding developments across the mid- and higher latitudes of the
Pacific do become characterized by increasing spread. However, it is
not yet clear how much impact this will have on downstream flow
across North America. It still appears that an increasingly
confluent northwesterly mid-level regime, between persistent ridging
across the eastern Pacific into western North America and downstream
troughing, may support the development of another expansive surface
ridge east of the Rockies into the Gulf Basin and Atlantic Seaboard
late this week through next weekend. This is likely to further
impede deep boundary-layer moistening over the northwestern Gulf.
Coupled with the lack of a developing southerly return flow from
the Gulf Basin until at least early next week, it appears that
generally stable conditions will be maintained through this period.

..Kerr.. 12/07/2025

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ACUS48 KWNS 080927
SWOD48
SPC AC 080925

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0325 AM CST Mon Dec 08 2025

Valid 111200Z - 161200Z

...DISCUSSION...
Downstream of a prominent blocking high, which may be maintained
near/north of the Aleutians vicinity through this period, latest
medium-range output suggests that flow across the mid-latitude
Pacific through North America may trend less amplified by next
weekend into early next week. Relatedly, guidance is becoming more
unclear how impactful cold air, initially building to the lee of the Canadian/northern U.S. Rockies by late this week, will be in terms
of drying across the northern Gulf Basin, as it noses
south/southeastward in one or two surges through the remainder of
the period.

It now appears at least a bit more of a possibility that a weak to
modest elevated, if not boundary-layer based, Gulf moisture return
could occur on a developing southerly return flow, across parts of
the northwestern Gulf coast into southern Great Plains next weekend
into early next week. This could promote destabilization supportive
of a risk for thunderstorm development. However, with surface
cyclogenesis appearing unlikely to the lee of the southern Rockies,
the potential for severe weather appears low in the presence of
limited large-scale forcing for ascent and vertical shear.

..Kerr.. 12/08/2025

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ACUS48 KWNS 090929
SWOD48
SPC AC 090927

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0327 AM CST Tue Dec 09 2025

Valid 121200Z - 171200Z

...DISCUSSION...
Medium-range models indicate that at least a couple of short wave
troughs, digging within an initially strong northwesterly regime
across and to the east-southeast of the Canadian Rockies, will
contribute to reinforcement of large-scale troughing farther
downstream late this work week into next weekend. As this occurs,
cold surface ridging building to the lee of the Canadian and
northern U.S. Rockies is forecast to eventually overspread much of
the central and eastern U.S., offshore Atlantic and northwestern
Gulf Basin by the beginning of next week.

Based on the past few model runs, it appears that an initial
southeastward surge of cold air may weaken before reaching the Gulf
coast, allowing for a gradual boundary-layer modification over the
northwestern Gulf Basin to continue, before the more substantive
surge of cold air reaches the northern Gulf by late this weekend.
Particularly in association with the stronger front, if not also the
weaker initial one, a moistening elevated and perhaps boundary-layer
based return flow may contribute to sufficient destabilization to
support a risk for thunderstorms, anywhere in a corridor from
southeastern Texas toward the Mid South and Tennessee Valley.
However, with any surface frontal wave development forecast to
remain weak, the risk for severe weather is likely to remain low.

Into early next week, model output becomes more varied, but it
appears that flow may trend more zonal across the northern
mid-latitudes of North America. In lower latitudes, another
developing moist southerly return flow, in advance of troughing
digging across the southern Rockies and Great Plains, may contribute
to renewed thunderstorm development across the northwestern Gulf
coast vicinity. However, the potential for severe weather still
seems limited at this time.

..Kerr.. 12/09/2025

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ACUS48 KWNS 100915
SWOD48
SPC AC 100914

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0314 AM CST Wed Dec 10 2025

Valid 131200Z - 181200Z

...DISCUSSION...
Based on the latest medium-range model output, a vigorous digging
short wave trough is likely to contribute to substantive mid-level
trough amplification once again across the Upper Midwest/Great Lakes
and Ohio Valley, into and across the Mid Atlantic Seaboard this
coming weekend. It appears that this may provide support for
significant cyclogenesis along a frontal zone across the
northwestern Atlantic, while a strongly confluent mid-level regime
in its wake supports the southeastward development of a large cold
surface ridge across most areas east of the Rockies, including the
offshore Atlantic and Gulf Basin by early next week.

Thereafter, into the middle of next week, mid-level flow may trend a
bit more zonal, at least across the northern mid-latitudes of North
America. However, there is notable spread evident within and among
the various model output concerning short waves emerging from the
upstream blocking pattern, before progressing inland within
splitting branches of westerlies across and east of the Rockies.
After an initial suppression of Gulf boundary-layer moistening early
next week, a developing southerly return flow with moistening that
may lead to increasing convective potential appears possible across
and northeast of the northwestern Gulf coast/lower Mississippi
Valley vicinity. The extent to which this could include a risk for
severe storms remains unclear, but currently still appears generally
low through at least this period.

..Kerr.. 12/10/2025

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ACUS48 KWNS 110929
SWOD48
SPC AC 110928

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0328 AM CST Thu Dec 11 2025

Valid 141200Z - 191200Z

...DISCUSSION...
Latest medium-range model output indicates that the amplified
trough, likely digging through the lower Great Lakes and Ohio Valley
at the outset of the period, will continue rapidly digging across
the U.S. Atlantic Seaboard, before pivoting offshore and supporting
strong cyclogenesis through the northwestern Atlantic into early
next week. In its wake, an initially expansive cold surface ridge,
centered near the mid/lower Missouri Valley, may gradually weaken,
but is forecast to continue southeastward into and across the
offshore Atlantic, Florida Peninsula and much of the northern Gulf
Basin.

Thereafter, it still appears that mid/upper flow may trend more
zonal, particularly across the northern U.S. and southern Canada,
downstream of a blocking high that is forecast to be maintained, but
become suppressed to the south of the Aleutians. Short wave
developments embedded within this regime remain uncertain, but there
is still at least some signal that a developing southerly return
flow may support a modest influx of moisture off the northwestern
Gulf by the middle of next week. This could contribute to
thunderstorm development across parts of the Mid South through
portions of the lower Ohio and Tennessee Valleys Wednesday into
Thursday, ahead of a modest cold front. However, at this time, it
appears that some combination of weak/limited destabilization and
modest shear/forcing for ascent will tend to minimize the risk for
severe storms.

..Kerr.. 12/11/2025

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ACUS48 KWNS 120921
SWOD48
SPC AC 120919

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0319 AM CST Fri Dec 12 2025

Valid 151200Z - 201200Z

...DISCUSSION...
Strong high pressure will dominate the eastern CONUS on Monday with
offshore flow across then entire Gulf Coast and East Coast. This
dry, continental polar airmass across the eastern CONUS will result
in no thunderstorms east of the Rockies on Monday and Tuesday. Some thunderstorms are possible along the coastal Pacific Northwest where
some weak instability may be present.

By the middle of next week, moisture return should resume across
Texas. This may result in some thunderstorm activity by early
Wednesday in the east Texas vicinity. Beyond Wednesday, model
uncertainty increases substantially. However, severe potential will
still remain too low as even the most favorable mid-long range
guidance indicates minimal instability and low severe weather
threat.

..Bentley.. 12/12/2025

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ACUS48 KWNS 130847
SWOD48
SPC AC 130846

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0246 AM CST Sat Dec 13 2025

Valid 161200Z - 211200Z

...DISCUSSION...
Moisture return will begin on Tuesday/D4 across Texas with some weak instability and thunderstorm potential arriving by Wednesday/D5.
Significant differences in the upper-level pattern begin on
Thursday/D6 and beyond which will significantly impact thunderstorm
and severe weather potential.

The ECMWF and AIFS have a sharper mid-level trough farther south on Thursday/D6. This will result in a stronger cold front and farther
north moisture return ahead of the front. In addition, some weak
instability may develop beneath the stronger mid-level jet. This may
create an environment favorable for a few stronger storms from the
Lower Ohio Valley to the Mid-Mississippi Valley. This stronger
scenario would likely push a strong cold front deep into the Gulf on
Friday and limit thunderstorm potential into the weekend.

A less amplified solution (as shown by the GFS and AIGFS) would not
support much of any strong storm threat on Thursday/D6. However, it
would keep low to mid 60s dewpoints across Texas and the Lower MS
Valley on Friday and into the weekend. This may result in weak to
potentially moderate instability across portions of the southern
Plains and possibly into the Mid-Mississippi Valley through the
weekend. Despite this lingering instability, a mostly zonal
mid-level pattern would not support a significant severe weather
threat.

Overall, severe weather potential remains somewhat low for much of
the period. Some low-end severe weather threat may exist from
Thursday/D6 and beyond as low-level moisture increases, but
significant uncertainties in the evolution of the upper-level
pattern make any forecast for time or location of any potential
low-end threat difficult.

..Bentley.. 12/13/2025

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ACUS48 KWNS 140958
SWOD48
SPC AC 140956

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0356 AM CST Sun Dec 14 2025

Valid 171200Z - 221200Z

...DISCUSSION...
Northward moisture return is expected to persist through the period
on D4/Wednesday as a strong surface low moves across the northern
Plains and Upper Midwest and strong southerly flow expands across
much of the warm sector. Despite the moisture advancing well inland,
warm air aloft should limit strong thunderstorm potential on
D4/Wednesday.

By D5/Thursday, weak to moderate instability is expected from East
Texas to the Mid-Mississippi Valley. Strong shear will be present
north of I-20 as a mid-level trough amplifies and a strong mid-level
jet overspreads the warm sector. Despite the presence of strong
shear and weak to moderate instability, updraft intensity may still
struggle due to weak lapse rates/warm air aloft. Only weak height
falls/cooling temperatures aloft are forecast south of the MO
Bootheel. Thunderstorms are likely from the Mid-Mississippi Valley
northward, where forcing will be stronger, but these regions will
remain well north of the more favorable instability. Therefore, any
severe weather threat would likely be marginal.

The cold front, associated with the storm system on D5/Thursday,
will move off the East Coast early on D6/Friday. Some marginal
severe weather may be possible Friday morning, but otherwise, severe
weather potential will be low as high pressure builds east of the MS
River in its wake.

By this weekend, return flow is anticipated across portions of the
southern Plains, but destabilization remains uncertain. A zonal
mid-level pattern with multiple embedded shortwave troughs is
currently forecast during that timeframe which commonly results in
considerably low predictability. Regardless of the exact outcome
over the weekend, there is general consensus for zonal flow and a
ridge building across the western CONUS and into the Plains. In
general, this will likely not support a significant severe weather
threat.

..Bentley.. 12/14/2025

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ACUS48 KWNS 150951
SWOD48
SPC AC 150949

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0349 AM CST Mon Dec 15 2025

Valid 181200Z - 231200Z

...DISCUSSION...
...D4/Thursday - Mid-Mississippi Valley and Lower Ohio Valley to the Southeast...
Isolated severe storms are possible on Thursday as moisture expands
northward ahead of a strong cold front. Forecast soundings show
strong shear across the region, but limited instability as 60+ F
dewpoints struggle to make it north of I-20. Given the strength of
the low-level jet, some damaging wind gusts are possible, but a
greater threat is not anticipated due to the aforementioned limited instability.

...D5/Friday - Carolinas to Georgia Coast...
Thunderstorms may be ongoing near the Carolina/Georgia coast on
Friday morning, but will quickly move into the Atlantic as a cold
front advances eastward. In addition, this front will move into the
Gulf and push rich moisture well offshore. As a result, thunderstorm
potential should be limited for the remainder of the D5 period.

...D6/Sat-D7/Sun - TN Valley into the Southeast...
Return flow will resume once again across the western Gulf over the
weekend. 60F dewpoints are expected to advect inland across East
Texas and Louisiana. This richer moisture may eventually interact
with a southeastward moving cold front at the end of D6 and into D7
with some thunderstorm potential. A few stronger storms may be
possible if sufficient instability can develop.

..Bentley.. 12/15/2025

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ACUS48 KWNS 160858
SWOD48
SPC AC 160856

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0256 AM CST Tue Dec 16 2025

Valid 191200Z - 241200Z

...DISCUSSION...
A line of storms will likely be ongoing from portions of the
Northeast into the mid-Atlantic and Carolinas Friday morning. If
sufficient destabilization can occur, a few isolated damaging wind
gusts will be possible before the front moves offshore. In the wake
of this cold front, an extended period of low severe potential
begins. By Saturday afternoon, moisture is forecast to advect inland
across East Texas and Louisiana, but no thunderstorm activity is
expected. 60s dewpoints will remain along the Gulf Coast from Texas
to inland Louisiana and Mississippi through the weekend and into
early next week. However, building heights aloft will limit
thunderstorm potential for much of the extended. Even if some
thunderstorms occur early next week, as indicated by the 00Z ECMWF
across MS/TN, they will likely remain south of the stronger
mid-level flow and without strong destabilization, will be unlikely
to be severe.

..Bentley.. 12/16/2025

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ACUS48 KWNS 170958
SWOD48
SPC AC 170957

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0357 AM CST Wed Dec 17 2025

Valid 201200Z - 251200Z

...DISCUSSION...
Southerly low-level flow will return to the southern Plains on
D4/Saturday. This will bring 60sF dewpoints to east Texas and much
of Louisiana with weak destabilization anticipated. A few storms may
be possible across Louisiana on Saturday night, but shear will be
weak. Minimal vertical shear combined with limited forcing and only
weak instability will preclude any severe weather threat.

Isolated thunderstorm activity is possible from D5/Sunday through
the first half of next week from East Texas and Louisiana into the
Ozarks and into the Midwest as slight enhancements of the low-level
jet promote isentropic ascent. Through this period, low to mid 60s
dewpoints will progressively advance farther inland. However,
instability should remain weak as mid-level heights build and
mid-level temperatures warm. Therefore, despite the inland moisture
early next week, severe weather potential remains low due to weak
instability, weak forcing, and building heights aloft.

..Bentley.. 12/17/2025

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ACUS48 KWNS 180904
SWOD48
SPC AC 180903

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0303 AM CST Thu Dec 18 2025

Valid 211200Z - 261200Z

...DISCUSSION...
An expansive area of high pressure will build across the eastern
CONUS on D4/Sunday and push a frontal zone near the Gulf Coast.
After this, ridging will build across the central CONUS and allow
rich moisture to advance well inland from the southern Plains to the
Midwest by D7/Wednesday. However, building heights aloft will result
in minimal if any forcing for thunderstorm development during this
period. Even beyond day 7, model guidance shows decent agreement in
a modest ridge breakdown without much severe weather concern.

..Bentley.. 12/18/2025

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ACUS48 KWNS 191002
SWOD48
SPC AC 191000

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0400 AM CST Fri Dec 19 2025

Valid 221200Z - 271200Z

...DISCUSSION...
The large-scale mid-level flow pattern during the upcoming week will
feature ridging/anomalously high 500-mb heights over much of the
central U.S., and southwesterly flow with embedded disturbances
across the western states. Although low-level moisture will expand north/northeast from the southern Plains and Southeast into the
Midwest/OH Valley region during the week, instability will remain
generally limited due to warm mid-level temperatures. Overall, the
potential for organized severe storms is expected to remain low each
day.

..Bunting.. 12/19/2025

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ACUS48 KWNS 200838
SWOD48
SPC AC 200836

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0236 AM CST Sat Dec 20 2025

Valid 231200Z - 281200Z

...DISCUSSION...
The large-scale pattern next week will be highlighted by prominent
upper ridging and anomalously high 500-mb heights over much of the
central to eastern CONUS, with upper troughing developing toward the
West Coast by mid/late week. This pattern should considerably limit
deep convective potential over much of the CONUS, even while a
relatively warm/moist airmass will exist across the Plains and
Midwest.

With the approach of a low-latitude upper trough and increasing
moisture, thunderstorm potential, potentially including some
strong/locally severe storms with gusty winds, could occur across
coastal portions of central and southern California during the last
half of Wednesday/Day 5 into Thursday/Day 6 Christmas. However, the
degree of destabilization and some synoptic-related forecast details
remain uncertain.

..Guyer.. 12/20/2025

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ACUS48 KWNS 210921
SWOD48
SPC AC 210920

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0320 AM CST Sun Dec 21 2025

Valid 241200Z - 291200Z

...DISCUSSION...
Medium-range model guidance initially shows a pattern featuring an
upper ridge over the central CONUS and trough along the West Coast, transitioning to a more progressive flow regime and lowering heights
across the Great Plains during the Thursday-Saturday (D5-D7) period.
The inland-moving West Coast trough will potentially yield isolated
to scattered thunderstorms on Wednesday into early Thursday over
portions of southern and central CA and perhaps a localized risk for
a couple of stronger thunderstorms. Details concerning this
convective scenario and overall magnitude of severe risk preclude
severe highlights. Farther east, some moisture return northward
into the southern Great Plains and MS Valley through Friday will
likely be modulated by frontal advancements during the latter part
of extended period.

..Smith.. 12/21/2025

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ACUS48 KWNS 220927
SWOD48
SPC AC 220925

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0325 AM CST Mon Dec 22 2025

Valid 251200Z - 301200Z

...DISCUSSION...
An upper-air pattern featuring a ridge over the central states will
quickly transition to a more progressive flow regime towards early
this weekend. Model guidance implies a split-flow regime
potentially evolving with troughing over the Great Lakes towards the Sunday-Monday timeframe (D7-D8). Overall limited potential for
organized severe seemingly exists for much of the extended period.
Some indication for a moist sector evolving ahead of the amplifying
Great Lakes' trough could yield some severe risk, but predictability
is low and highly uncertain given model spread at this point in
time.

..Smith.. 12/22/2025

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ACUS48 KWNS 230943
SWOD48
SPC AC 230941

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0341 AM CST Tue Dec 23 2025

Valid 261200Z - 311200Z

...DISCUSSION...
From Friday/Day 4 to Sunday/Day 6, a mid-level ridge is forecast to
move eastward from the central U.S. to the Eastern Seaboard. During
this time, a trough is forecast to develop in the Pacific Northwest,
and then to dig southeastward into the mid Mississippi Valley. An
associated cold front is forecast to move southeastward into the
Ohio and Tennessee Valleys by Sunday afternoon. Ahead of the front,
surface dewpoints in the 60s F should result in weak destabilization
with thunderstorm development possible along the front. However, the
models suggest that most of the convection will be post-frontal.
This limitation should keep any severe threat marginal.

On Monday/Day 7 and Tuesday/Day 8, the trough is forecast to move
across the eastern U.S. into the western Atlantic, with the front
moving off the Atlantic coast. In its wake, a relatively dry and
cool airmass will make thunderstorm development unlikely across most
of the nation.

..Broyles.. 12/23/2025

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ACUS48 KWNS 240943
SWOD48
SPC AC 240942

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0342 AM CST Wed Dec 24 2025

Valid 271200Z - 011200Z

...DISCUSSION...
This weekend, a mid-level ridge will move from the mid Mississippi
Valley eastward to the Atlantic Seaboard, as a trough digs
southeastward into the north-central U.S. A moist airmass will
advect northeastward into the Ohio and Tennessee Valleys, ahead of a
cold front moving through the mid Mississippi Valley. Thunderstorm
development, mostly post-frontal in nature, will be possible Sunday
afternoon from the Arkansas River Valley northeastward into the Ohio
Valley. Although an isolated severe threat may develop, the storms
should be elevated and the threat will be limited by weak
instability. On Monday, the cold front is forecast to move to the
southern Atlantic Seaboard, with a dry and cool airmass residing
over much of the nation. This dry airmass is forecast to remain in
place through mid-week, keeping the chance for thunderstorms low
across the continental U.S.

..Broyles.. 12/24/2025

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ACUS48 KWNS 250948
SWOD48
SPC AC 250946

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0346 AM CST Thu Dec 25 2025

Valid 281200Z - 021200Z

...DISCUSSION...
A mid-level trough is forecast to move eastward across the central
U.S. on Sunday, as an associated cold front advances southeastward
into the Ozarks and mid Mississippi Valley. Near the front,
scattered thunderstorms are expected by afternoon from the
Ark-La-Tex northeastward into the lower Ohio Valley. Any severe
threat will likely remain marginal due to weak instability, and a
tendency for storms to be post-frontal.

From Monday to Thursday, the mid-level trough is forecast to
gradually move eastward across the central and eastern U.S.,
eventually reaching the western Atlantic by Thursday. In its wake, a
cool and dry airmass is forecast to overspread much of the
continental U.S., making conditions unfavorable for thunderstorms in
most areas.

..Broyles.. 12/25/2025

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ACUS48 KWNS 260855
SWOD48
SPC AC 260853

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0253 AM CST Fri Dec 26 2025

Valid 291200Z - 031200Z

...DISCUSSION...
D4/Monday will feature conditionally favorable strong low to
mid-level flow along/ahead of a cold front moving east across the
Southeast. The intense eastern Great Lakes/southeast ON cyclone
should occlude as a secondary cyclone forms along coastal ME into
the Canadian Maritimes. Guidance is fairly consistent for this time
frame with indications of minimal instability along the trailing
portion of the cold front, as well as diminishing large-scale
ascent/convective signal through the day. Severe thunderstorm wind probabilities appear at or below 5 percent.

The continental airmass spreading across the Gulf in the wake of the
frontal passage should yield minimal severe potential mid-week.
Towards late week, return flow will support airmass modification
along the western Gulf Coast. The EC-AIFS hints at a low-amplitude
shortwave impulse in the D8/Friday time frame, which could support a
return to non-negligible severe potential.

..Grams.. 12/26/2025

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ACUS48 KWNS 270844
SWOD48
SPC AC 270842

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0242 AM CST Sat Dec 27 2025

Valid 301200Z - 041200Z

...DISCUSSION...
A quiescent pattern is expected mid-week, in the wake of a D2-3
continental air mass intrusion across much of the Gulf. Return flow
and air mass modification will ensue late week into next weekend.
Run-to-run predictability remains low by this time frame, but some
models suggest a southern-stream shortwave trough could interact
with this moistening plume. This may support non-negligible severe
potential over the western Gulf States towards D8. Even this
scenario appears to be of sufficiently marginal amplitude, outside
of a singular 00Z CMC outlier, to likely yield low severe
probabilities through next Saturday. GEFS-based SPC-CSU and NSSL ML
guidance are in alignment with sub-5 percent severe probs on D8.

..Grams.. 12/27/2025

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ACUS48 KWNS 280840
SWOD48
SPC AC 280838

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0238 AM CST Sun Dec 28 2025

Valid 311200Z - 051200Z

...DISCUSSION...
Return flow will ensue along the western Gulf Coast mid-week,
yielding air mass modification from the prior continental intrusion.
Bulk of deterministic guidance has trended toward earlier EC-AIFS
signals of a low-amplitude shortwave trough progressing east across
the southern states through late week. While run-to-run
predictability and spread across models remains subpar, convective
potential should increase by D6-7/Friday-Saturday across parts of
the Gulf Coast States. At this point, with only modest cyclogenesis consistently progged, overall severe potential still appears
marginal. Latest ML guidance from SPC-CSU and NSSL for the GEFS, and yesterday's NCAR for the ECENS, support this notion with individual
day probabilities holding at 5 percent or less.

..Grams.. 12/28/2025

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ACUS48 KWNS 290912
SWOD48
SPC AC 290911

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0311 AM CST Mon Dec 29 2025

Valid 011200Z - 061200Z

...DISCUSSION...
Guidance consensus indicates a lower-amplitude shortwave trough will
approach the southern CA coast at 12Z Thursday. This feature appears increasingly likely to progress east across the southern states
through late week, initially inducing cyclogenesis over the southern
High Plains. This will aid in strengthening low-level moisture
return over the western Gulf, after a pervasive continental air mass
intrusion today.

Increasing convective potential is anticipated around late D5/Friday
to D6/Saturday across the Gulf Coast States from LA to north FL, and
into parts of the Deep South. Run-to-run-predictability and spread
across guidance remains less-than-ideal for timing/location of amplification/dampening details for this shortwave trough. Bulk of
signals are still for a modest surface cyclone and seemingly
lower-end severe risk. But there's enough minority signal to warrant
concern for a potential 15 percent area in later outlook cycles.

..Grams.. 12/29/2025

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ACUS48 KWNS 300848
SWOD48
SPC AC 300847

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0247 AM CST Tue Dec 30 2025

Valid 021200Z - 071200Z

...DISCUSSION...
A return of deep convection remains likely on D4-5/Friday-Saturday
across the Gulf Coast States from LA to north FL, and into the Deep
South. A low-amplitude shortwave impulse should emanate out of the
Southwest and may briefly amplify on D4/Friday over TX, as it
becomes absorbed within the broader cyclonic flow regime across
eastern North America. Latest guidance has decidedly trended towards
dampening this impulse and attendant surface cyclone reflection as
they progress across the Gulf Coast States/northern Gulf Friday
night into Saturday. This combined with predominately westerly
low-level wind profiles may support only a marginal severe threat.
After this minor wave, severe potential appears negligible in the
D6-8 time frame.

..Grams.. 12/30/2025

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ACUS48 KWNS 310953
SWOD48
SPC AC 310951

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0351 AM CST Wed Dec 31 2025

Valid 031200Z - 081200Z

...DISCUSSION...
Primary severe concern will be across the northeast Gulf Coast
States, during the morning to afternoon on D4/Saturday. A
lower-amplitude shortwave trough remains consistently progged to
dampen as it progresses quickly across the Southeast and northeast
Gulf. With a weak surface cyclone, low-level winds should remain
veered. But this should be adequate for weak buoyancy to spread
east, emanating from the northwest Gulf and LA. With a more robust
convective signal closer to the coast compared to D3/Friday, at
least a level 1-MRGL risk should be warranted. This is supported by
latest SPC-CSU and NSSL GEFS-based ML guidance with overlapping 5
percent probability areas.

Along coastal CA, while run-to-run predictability is poor, latest
guidance has some signal for low-topped supercell potential this
weekend, downstream of a large-scale trough off the Pacific Coast.
This appears generally focused across northern CA on D4/Saturday,
shifting to southern CA on D5/Sunday. Spatiotemporal aspects of
individual shortwave impulses and attendant mid-level jetlets
relative to probable scant/meager buoyancy profiles will be crucial
for delineating areal highlights in shorter-term outlooks.

Otherwise, a combination of low potential/predictability remains
evident early next week.

..Grams.. 12/31/2025

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ACUS48 KWNS 010935
SWOD48
SPC AC 010933

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0333 AM CST Thu Jan 01 2026

Valid 041200Z - 091200Z

...DISCUSSION...
Severe potential appears low through much of the period, with an
increase possible late next week. While run-to-run predictability
has been poor, latest guidance appears to be trending somewhat more consistently with the evolution of an upper trough off the West
Coast. This feature may evolve as a lower-latitude wave across Baja
CA and northern Mexico, or along the international border in the
Southwest States, before eventually emerging near TX. While
predictability is low for spatiotemporal aspects of this wave, it
may eventually interact with a modifying warm-moist sector from the
western Gulf into the South-Central States. SPC-CSU GEFS ML probs
highlight a 5 percent on D8/Thursday (although seemingly biased too
far north). Meanwhile, NSSL GEFS ML V1.2 probs highlight only a 2
percent on D8, but have a 10 percent on D9/Friday.

..Grams.. 01/01/2026

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ACUS48 KWNS 020940
SWOD48
SPC AC 020939

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0339 AM CST Fri Jan 02 2026

Valid 051200Z - 101200Z

...DISCUSSION...
Convective potential appears likely to increase across at least the South-Central States, centered on eastern TX to the Lower MS Valley
mid to late week. While day-to-day predictability is low, the
broader signal hints at potentially multiple days of at least
low-probability severe during D6-9/Wednesday-Saturday.

Initial concern is with the downstream evolution of a lower-latitude
shortwave trough across Baja CA and northwest Mexico early in the
week. Guidance continues to struggle with spatiotemporal aspects of
this wave by mid-week. But potential exists for this wave to
interact with a modifying warm-moist sector from the western Gulf
into the South-Central States. Faster guidance indicates
severe-storm potential may commence by late Wednesday.

In the wake of the initial shortwave trough, guidance consensus
suggests that a broad upper trough should evolve across the West
late week. This may yield an expansive swath of fast mid-level
southwesterlies from the southern High Plains to the Northeast.
Given a lack of frontal intrusion into the northwest Gulf with the
lead wave, seasonably rich low-level moisture may overlap a portion
of this fast flow regime around Friday-Saturday. Latest NSSL GEFS ML
V1.2 probs appear reasonable with depictions of 5 percent peak probs
on D6-7, followed by 10 percent areas on D8-9.

..Grams.. 01/02/2026

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ACUS48 KWNS 030932
SWOD48
SPC AC 030931

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0331 AM CST Sat Jan 03 2026

Valid 061200Z - 111200Z

...DISCUSSION...
Convective potential appears likely to increase across at least the South-Central States by late week. Guidance spread remains large
with the handling of a lower-latitude shortwave trough that will
initially be off the southern CA/Baja CA coast on D4/Tuesday.
Non-ECMWF deterministic guidance largely eject this wave quickly east-northeastward into the southern Great Plains by late
D5/Wednesday night. The ECMWF, EC-AIFS, and AIGFS maintain a slower
and more reasonable scenario of progression through D6/Thursday.
This will probably interact with a modifying warm-moist sector from
the western Gulf, with some severe potential in a portion of the
South-Central States. Spatiotemporal detail differences exist even
among the preferred slower guidance and the majority of GEFS/ECENS
ML probs remain below 15 percent for Thursday.

For the broad upper trough over the West, latest EC-AIFS and the
ECMWF now depict potential of a negative-tilt evolution compared to
prior runs and other guidance. Spread is quite large within the
ECENS for both the AI/non-AI, indicative of a poorly predictable
pattern for shortwave impulses embedded within the broader trough.
But with potential for fast mid-level southwesterlies overlapping
seasonably rich low-level moisture emanating north from the western
Gulf, and some scenarios indicative of cyclogenesis over the central
states, a severe area highlight may eventually be warranted on
D7/Friday.

..Grams.. 01/03/2026

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ACUS48 KWNS 040932
SWOD48
SPC AC 040931

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0331 AM CST Sun Jan 04 2026

Valid 071200Z - 121200Z

...DISCUSSION...
A low-latitude closed low west of Baja CA at 12Z Wednesday should
evolve back into an open wave, aided by the development of a
large-scale trough becoming established over the West. EC-AIFS and
AIGFS remain the preferred guidance for a more probable slower
ejection of the low-latitude wave onto the southern Great Plains
through Thursday. At least isolated severe potential seems plausible
to the east-southeast of a southern High Plains lee cyclone as a
modifying warm-moist sector advects north from the western Gulf. But yesterday's NCAR ECENS-based ML guidance remains below 5 percent for
Thursday, while the latest GEFS-based SPC-CSU and NSSL ML guidance
have trended lower to only 5 percent peak areas.

D6/Friday still appears to have the best relative severe potential,
despite the pair of GEFS-based ML guidance trending lower and in
areal extent of 5 percent peak probs. Neither of these have any
appreciable overlap with the preferred ECENS-based 5 percent areas
from NCAR. In any case, an amplified upper trough appears likely to
shift from around the Rockies to the Great Plains. Most EC-AIFS ENS
members now support central states cyclogenesis. But predictability
remains low regarding the spatiotemporal details and amplitude of
cyclogenesis, which is likely related to the handling of shortwave
impulses embedded within the broader trough. An area-of-interest for
a future 15 percent severe highlight roughly includes the Lower MS
to TN Valleys and Deep South.

..Grams.. 01/04/2026

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ACUS48 KWNS 050951
SWOD48
SPC AC 050949

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0349 AM CST Mon Jan 05 2026

Valid 081200Z - 131200Z

...DISCUSSION...
The noticeable model differences on D3/Wednesday in the evolution of
a low-latitude shortwave impulse, ejecting ahead of an amplifying
upper trough over the West, persist into D4/Thursday. This renders
low confidence in a greater than low-probability severe risk on
Thursday, which appears roughly centered on the Ark-La-Tex to
Mid-South.

Peak severe potential still appears centered on D5/Friday.
Predictability remains sub-optimal with the basal portion of the
amplified upper trough from the Southwest. This renders large spread
across guidance in timing and amplitude of downstream cyclogenesis
from the south-central Great Plains towards the Great Lakes,
impacting the breadth of severe potential. However, with preceding
days of airmass modification from the western Gulf, a pronounced
wintertime warm-moist sector should become established towards the
Lower OH Valley vicinity. This should be coincident with a broad
swath of strong southwesterly mid-level flow that should be
strengthening during the period.

The trio of latest NCAR ECENS-based and SPC-CSU GEFS-based ML
probabilities have trended upward again with similarly large 15
percent regions. Meanwhile, the NSSL GEFS-based V1.2 has increased
back to a 10 percent, but displaced farther south. For this
forecast, have opted to include a 15 percent highlight, centered on
the Lower MS to Lower OH Valleys where confidence is greater for a
favorable convective environment on Friday afternoon to night
despite the modest synoptic-scale predictability.

ML probs for D6/Saturday remain low, with only the NCAR_Pangu
highlighting a 5 percent area. But given the aforementioned timing
differences with the evolution of the upper trough/surface
cyclogenesis, very fast deep-layer wind fields could persist atop a
more limited thermodynamic environment. A conditional convective
damaging wind threat seems apparent, with low confidence on spatial extent/amplitude at this time range.

..Grams.. 01/05/2026

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ACUS48 KWNS 061002
SWOD48
SPC AC 061000

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0400 AM CST Tue Jan 06 2026

Valid 091200Z - 141200Z

...DISCUSSION...
...D4/Friday: Lower MS Valley vicinity...
A mid/upper-level shortwave trough initially over the southern
Rockies is forecast to take on a positive tilt as it moves eastward
on Friday, as a northern-stream shortwave trough digs from the
Canadian Prairies toward the Upper Great Lakes. Some guidance has
trended weaker and farther south with a surface low developing near
the lower MS Valley by Friday evening, though a relatively large
warm sector is still expected to be in place through most of the
period. Scattered to widespread storm development is expected from
parts of east TX into the lower MS Valley, with sufficient
deep-layer shear for organized convection and some attendant severe
threat. Some adjustments to the 15% area have been made, based on
guidance trends regarding surface low placement and the northward
extent of the favorable warm sector.

...D5/Saturday: Parts of the East...
Uncertainty regarding the synoptic pattern increases by D5/Saturday,
with varying solutions regarding the extent of mid/upper-level
trough amplification across the eastern CONUS, and the strength of
the related surface low. Guidance generally agrees that buoyancy
will be limited across much of the warm sector on Saturday. However,
any organized convection that develops Friday night may persist into
Saturday morning across parts of the Southeast, with some potential
for an isolated severe threat. Farther north, the strongest
solutions (such as the 00Z deterministic ECMWF) depict notable
intensification of low/midlevel flow from the Ohio Valley into the
Mid Atlantic, which could result in some damaging-wind potential
with any low-topped convection along or ahead of an advancing cold
front.

..Dean.. 01/06/2026

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ACUS48 KWNS 070917
SWOD48
SPC AC 070915

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0315 AM CST Wed Jan 07 2026

Valid 101200Z - 151200Z

...DISCUSSION...
...D4/Saturday...
Some severe potential remains evident from parts of the Southeast
into the Carolinas, Mid Atlantic, and possibly Ohio Valley on
D4/Saturday, but details remain uncertain.

Guidance generally depicts continued amplification of a deep and
progressive shortwave trough on Saturday across the eastern CONUS. A
deepening surface low is forecast to move from the Ohio Valley
toward the Lower Great Lakes, as a trailing cold front sweeps
through much of the Southeast and Mid Atlantic. Strongly sheared
convection with some severe potential may be ongoing Saturday
morning along/ahead of the cold front, from parts of MS/AL into the
southern Appalachians. Strong deep-layer flow/shear will eventually
overspread parts of the Ohio Valley, Mid Atlantic and Carolinas.
However, longevity and magnitude of the severe threat in these
regions is uncertain, as instability weakens with northeastward
extent, and stronger ascent becomes increasingly displaced north of
the warm sector with time.

...D5/Sunday - D8/Wednesday...
The cold front is forecast to move through coastal NC and the FL
Peninsula on Sunday, but weak ascent and buoyancy are expected to
limit organized storm potential. Dry and stable conditions in the
wake of this cold frontal passage are expected to minimize
severe-storm potential across the CONUS into early next week.

..Dean.. 01/07/2026

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ACUS48 KWNS 080918
SWOD48
SPC AC 080916

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0316 AM CST Thu Jan 08 2026

Valid 111200Z - 161200Z

...DISCUSSION...
Organized severe potential currently appears low through the
extended-range period.

A cold front will move through coastal NC and parts of FL on
D4/Sunday, in advance of a deep upper trough moving across the
eastern CONUS, but ascent and buoyancy within the remaining warm
sector appear too weak to support organized storms. For D5/Monday
through D8/Thursday, generally dry and stable conditions in the wake
of multiple frontal intrusions will tend to limit thunderstorm
potential across most of the CONUS. Some guidance (notably the 00Z
ECMWF) indicates that thunderstorm chances may return to parts of
the FL Peninsula by mid week, in association with renewed upper
trough amplification across the eastern CONUS. However, with
guidance generally depicting only weak surface wave development
during this time frame, confidence in organized storm development
remains low.

..Dean.. 01/08/2026

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ACUS48 KWNS 090945
SWOD48
SPC AC 090943

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0343 AM CST Fri Jan 09 2026

Valid 121200Z - 171200Z

...DISCUSSION...
Mid-level northwesterly flow is forecast to become established
across the central U.S. on Monday. This appears likely to persist
into mid-week as a large-scale trough develops in the Mississippi
Valley. The pattern will help to usher cold and dry air southward
into the Great Plains and Southeast, which will limit moisture
return. From Thursday into Friday, the trough is forecast to move
into the eastern U.S., reinforcing northwesterly mid-level flow over
much of the nation. As a result, a cold and dry airmass is expected
to remain over the continental U.S, minimizing the potential for
thunderstorm development.

..Broyles.. 01/09/2026

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ACUS48 KWNS 100941
SWOD48
SPC AC 100940

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0340 AM CST Sat Jan 10 2026

Valid 131200Z - 181200Z

...DISCUSSION...
A large-scale upper-level trough is forecast to develop across the
central and eastern U.S. during the mid-week. This feature is
forecast to move eastward toward the Atlantic Seaboard late in the
week, as another trough takes its place further west across the
Mississippi Valley. In response to the pattern, a large area of high
pressure is forecast to settle into the central U.S. on Wednesday
and move slowly across the Gulf Coast region on Thursday and Friday.
Another large area of high pressure is forecast to move southward
into the western and central U.S. by the weekend. As a result, the
airmass across most of the continental U.S. during the mid to late
week should be cold and relatively dry, suggesting thunderstorm
development will be unlikely during the Day 4 to 8 period.

..Broyles.. 01/10/2026

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