ACUS48 KWNS 160858
SWOD48
SPC AC 160856

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0356 AM CDT Sun Mar 16 2025

Valid 191200Z - 241200Z

...DISCUSSION...
...Wednesday/Day 4 to Friday/Day 6...
A mid-level trough is forecast to move northeastward into the upper
Mississippi Valley on Wednesday. Ahead of the trough, a narrow axis
of moisture and weak instability is forecast from the western Great
Lakes into the lower Ohio Valley. This corridor of low-level
moisture will be the favored location for convective development
Wednesday afternoon. Surface dewpoints along the moist axis are only
expected to be in the 40s to lower 50s F. In spite of this, the exit
region of the mid-level jet is forecast to overspread the region
during the mid to late afternoon. This will provide strong lift and
deep-layer shear, sufficient for an isolated severe threat. Any
severe threat should remain marginal.

On Thursday, the trough is forecast move eastward through the Ohio
and Tennessee Valleys, as a cold front advances to near the Atlantic
Seaboard, from the eastern Carolinas into the Mid-Atlantic. Isolated
severe storms will again be possible along or ahead of the front
during the mid to late afternoon, but any threat is expected to be
marginal.

On Friday, a mid-level trough is forecast to move eastward into the
central states, where isolated convection will be possible. However,
moisture return is expected to be confined to the Texas Coastal
Plain, which will be a severe threat limiting factor.

...Saturday/Day 7 and Sunday/Day 8...
On Saturday, the trough is forecast to de-amplify and move into the northeastern U.S. as a broad low-amplitude cyclonic flow pattern
develops over much of the U.S. Moisture return is expected to take
place over the western Gulf Coast on Saturday and across the
southern Plains on Sunday. Some models suggest that a trough will
take shape in the Great Plains on Sunday, with a cluster of storms
forming ahead of the system Sunday afternoon. These storms would
develop along the northern edge of the stronger instability from
Oklahoma into Arkansas, expanding Sunday evening across the lower to
mid Mississippi Valley. If this scenario where to verify, then a
severe threat would be possible with the stronger storms within the
MCS. However, at this extended range, the magnitude and spatial
extent of any severe threat remains considerably uncertain.

..Broyles.. 03/16/2025

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ACUS48 KWNS 170858
SWOD48
SPC AC 170857

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0357 AM CDT Mon Mar 17 2025

Valid 201200Z - 251200Z

...DISCUSSION...
...Thursday/Day 4 to Saturday/Day 6...
On Thursday, a trough at mid-levels will move eastward into the
Appalachians, as a cold front advances quickly eastward across the
Atlantic Coastal states. Isolated strong gusts may occur with
convection that develops along or ahead of the front. The threat is
expected to be marginal.

On Saturday and Sunday, a mid-level trough is forecast to quickly
move from the High Plains to the East Coast. A moist airmmass in the
Gulf Coast region is forecast to remain largely in place as the
system passes to the north. This will likely limit any severe
potential.

...Sunday/Day 7 and Monday/Day 8...
From Saturday night into Sunday, moisture advection is forecast to
increase considerably over the southern Plains, as a mid-level
trough moves quickly southeastward across the central U.S.
Medium-range models suggest that the northern edge of the moist
airmass will be located from the Red River Valley eastward into the
lower Mississippi Valley by Sunday afternoon. Thunderstorm
development will be possible along this east-to-west corridor during
the late afternoon and evening, where the models suggest that
moderate instability and strong deep-layer shear will be in place.
Model spread appears low enough to add a 15 percent area, centered
on the Ark-La-Tex for Sunday.

On Monday, the trough is forecast to move eastward across the Ohio
and Tennessee Valleys, as a cold front advances quickly toward the
Atlantic Seaboard. Thunderstorms with an isolated severe threat will
be possible along and near the front during the afternoon, but
predictability is low concerning the timing of the front, and its
associated trough.

..Broyles.. 03/17/2025

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ACUS48 KWNS 180852
SWOD48
SPC AC 180850

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0350 AM CDT Tue Mar 18 2025

Valid 211200Z - 261200Z

...DISCUSSION...
...Friday/Day 4 to Saturday/Day 5...
On Friday and Saturday, a shortwave mid-level trough will move
eastward from the Great Plains to the Eastern Seaboard, as a long
fetch of west-northwest flow develops over much of the continental
U.S. Isolated convection may develop ahead of the trough, but
instability will likely be insufficient for a severe threat. In the
wake of this system, low-level moisture return will begin along the
western Gulf Coast. By Saturday, surface dewpoints are expected to
be the upper 50s and lower 60s F over the Texas and Louisiana
Coastal Plain.

...Sunday/Day 6 to Tuesday/Day 8....
On Sunday, moisture advection is forecast to increase over eastern
parts of the southern Plains into the Ark-La-Tex. A mid-level trough
is forecast to move across the central U.S. Ahead of the trough,
moderate instability is forecast to develop across much of a moist
airmass located from the southeastern third of Texas northeastward
into the Ark-La-Tex. On Sunday, thunderstorms with a threat for
isolated large hail and severe gusts are expected to develop along
the northern edge of the moist sector, with a complex of storms
moving southeastward across the Sabine and lower Mississippi Valleys
overnight.

On Monday and Tuesday, the mid-level trough is forecast to move into
the eastern U.S., as a cold front advances southward to near the
Gulf Coast. Although isolated storms could develop in the southern
Gulf Coast states, limited large-scale ascent is expected to be
problematic concerning an organized severe threat.

..Broyles.. 03/18/2025

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ACUS48 KWNS 190852
SWOD48
SPC AC 190850

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0350 AM CDT Wed Mar 19 2025

Valid 221200Z - 271200Z

...DISCUSSION...
...Saturday/Day 4 to Sunday/Day 5...
A mid-level trough will move through the central U.S. on Saturday
and Sunday, as moisture advection takes place across the southern
Plains, lower Mississippi Valley and Ark-La-Tex. Thunderstorm
development will likely take place ahead of the trough on Sunday
afternoon and evening, along the northern edge of the moist airmass
from the Red River Valley eastward into the lower Mississippi
Valley. A threat for large hail and severe wind gusts will be
possible within the more organized components of a developing MCS.
The MCS is forecast to move southeastward through the lower
Mississippi valley during the overnight period.

...Monday/Day 6 to Wednesday/Day 8...
On Monday, the trough is forecast to become amplified across the
Ohio and Tennessee Valleys, as a cold front moves southward through
the Gulf Coast states. Isolated severe storms could occur near the
central Gulf Coast early in the day, but the majority of the storms
are expected to move offshore into the Gulf. On Tuesday and
Wednesday, surface high pressure is forecast to settle over the
eastern half of the nation. This dry and cool airmass will make
conditions unfavorable for thunderstorms over most of the
continental U.S.

..Broyles.. 03/19/2025

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ACUS48 KWNS 200900
SWOD48
SPC AC 200858

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0358 AM CDT Thu Mar 20 2025

Valid 231200Z - 281200Z

...DISCUSSION...
...Sunday/Day 4 and Monday/Day 5...
A large-scale cyclonic flow pattern will be in place across much of
the continental U.S. on Sunday. An upper-level low will develop over
the Great Lakes, as an associated trough moves southeastward from
the Great Plains to the Mississippi Valley. A cold front is forecast
to move southeastward into the Ozarks. Ahead of the front, moisture
advection is forecast to occur over the Sabine and lower Mississippi
Valleys, where surface dewpoints will likely be in the 60s F and
moderate instability is expected to develop. Scattered thunderstorms
appear likely to initiate ahead of the front Sunday evening from the
Sabine River Valley northeastward into the Tennessee Valley, with an
MCS developing Sunday evening. Moderate deep-layer shear will likely
support severe thunderstorm development, with a potential for severe
wind gusts, isolated large hail. A tornado threat may also develop.

A cold front is forecast to move through the Gulf Coast region
Sunday morning. Isolated severe storms could develop ahead of the
front early in the day from the Texas Coast eastward to the central
Gulf Coast and Florida Panhandle. Predictability remains low
concerning where the greatest severe threat will be along this
corridor. The severe threat should end during the day as the front
moves southward into the Gulf.

...Tuesday/Day 6 to Thursday/Day 8...
On Tuesday, a mid-level trough is forecast to dig southeastward into
the Mississippi Valley. At the surface, a moist airmass will remain
over the Gulf Coast region. Isolated strong to severe storms could
occur along the northern edge of this moist airmass. The greatest
potential for severe could be across the Sabine River Valley, where
some solutions have moderate instability Tuesday afternoon. This
appears to be a conditional severe threat, and predictability is
low.

From Wednesday into Thursday, a relatively dry airmass is forecast
over much of the nation. The exception could be across south Texas,
where thunderstorm development will be possible. Although an
isolated severe threat would be possible there, predictability at
this extended range in the forecast cycle is low.

..Broyles.. 03/20/2025

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ACUS48 KWNS 210853
SWOD48
SPC AC 210851

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0351 AM CDT Fri Mar 21 2025

Valid 241200Z - 291200Z

...DISCUSSION...
Models suggest that a west-to-east cold front will move slowly
southward across the Gulf Coast states/Southeast on Monday/Day 4, as
an upper trough shifts slowly eastward across the eastern CONUS.
Ample instability should evolve along the front to support afternoon
storm development, but quasi-unidirectional flow with height, weak
at low levels, may hinder prospects for severe storms despite ample
mid-level flow. At this time, while some severe risk is apparent,
potential appears too low to warrant inclusion of a risk area at
this time.

The front should continue shifting southward while weakening Days
5-6 (Tuesday and Wednesday), as weak surface high pressure settles
into the eastern states. While thunder will be possible near the
Gulf Coast Tuesday, and lingering over Florida Thursday, severe risk
appears to be low.

Model differences begin to increase substantially beyond
Wednesday/through the end of the period. The ECMWF depicts a
substantial mid-level short-wave trough and accompanying surface
system moving into the Plains Day 8, while quasi-zonal flow aloft is
depicted by the GFS. As such, predictability concerns preclude
assessment of severe potential beyond Day 6.

..Goss.. 03/21/2025

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ACUS48 KWNS 220838
SWOD48
SPC AC 220837

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0337 AM CDT Sat Mar 22 2025

Valid 251200Z - 301200Z

...DISCUSSION...
Medium-range models are in reasonable agreement into the Day 6
(Thurs. Mar. 27) time period, after which divergence in solutions at
the synoptic scale begins to increase. This lack of predictability
in the latter half of the period results in lack of confidence with
respect to any assessment of severe-weather potential.

Through the first half of the period, severe-weather potential
appears limited -- particularly Days 4-5 (Tuesday and Wednesday of
next week). During this time period, an upper trough will advance
slowly eastward across the eastern U.S., with the main surface
baroclinic zone suppressed southward into the Gulf of America and
high pressure building in its wake.

Day 6, hints of a rather weak upper disturbance moving into the
southern Plains could support local/limited severe potential with a
few strong storms, but certainly not appearing sufficient in nature
to warrant an areal inclusion at this time.

..Goss.. 03/22/2025

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ACUS48 KWNS 230904
SWOD48
SPC AC 230902

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0402 AM CDT Sun Mar 23 2025

Valid 261200Z - 311200Z

...DISCUSSION...
Medium-range models appear to be in reasonable agreement with
large-scale features through Day 5 (Thursday Mar. 27), during which
time overall severe risk should remain generally tempered. A weak
surface warm front should lie from northwest-to-southeast across
Texas Day 4/Wednesday, with a secondary boundary lying
northwest-to-southeast from the northern High Plains to Kansas.
However, background ridging over the Rockies/western portions of the
Plains should suppress convection to some degree. This, along with
modest mid-level flow (generally 20 to 30 kt) expected across the
area will limit risk, though a few stronger central/southern High
Plains storms may evolve during the afternoon and evening.

On Day 5/Thursday, a weak southern-stream trough is forecast to
undercut the northern-stream ridge, shifting into the southern
Plains with time. While overall instability should once again
remain limited -- largely due to still-limited moisture return -- a
few stronger storms will again be possible during the afternoon and
evening. One area of more focused potential for a few storms
appears to exist over eastern portions of Nebraska and Kansas near
the slowly northward-advancing warm front; a few stronger afternoon
storms may also occur across portions of western Texas.

Day 6/Friday, models begin to diverge more substantially, with this
divergence increasing through the end of the period. Models hint
that a stronger trough may begin advancing across the West, and
into/across the Plains Days (next weekend). This would be
associated with stronger surface development, more robust northward
moisture transport, and more favorable flow aloft. Thus, while
severe risk appears likely to increase, differences in the models
with respect to details of this evolution preclude any confident
introduction of risk areas at this time.

..Goss.. 03/23/2025

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ACUS48 KWNS 240904
SWOD48
SPC AC 240902

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0402 AM CDT Mon Mar 24 2025

Valid 271200Z - 011200Z

...DISCUSSION...
Medium-range/global models have come into reasonable agreement with
respect to the most recent run, signaling toward heightened severe
risk over the upcoming weekend across central portions of the
country.

Days 4-5 (Thursday/Friday), locally strong storms will be possible
across a rather broad portion of the central of the country, from
the Upper Midwest to the southern Plains Day 4/Thursday, and the
Plains into the Ohio Valley Friday. This will occur as a
weak/slow-moving southern stream trough moves slowly
east-northeastward across this region. Somewhat limit risk, over a
broad geographic area, precludes introduction of any 15% risk areas
either of these two days.

Meanwhile, the primary synoptic pattern -- even early in the period
-- favors a persistent lee surface low/trough over the High Plains.
This will allow southerly low-level flow to evolve/expand across
almost all of the central and eastern portions of the country as a
warm front shifts northward into the northern CONUS.

By early Saturday/Day 6, height falls associated with a
strengthening trough moving across the Intermountain West should
begin to spread into the Plains, with the trough itself currently
expected to reach the High Plains. This will result in an eastward
advance of a surface low front out of the High Plains and across the
central Plains states through the evening/overnight. With a
moistening pre-frontal boundary layer ahead of the advancing system,
and increasing flow aloft, the overall setup will favor increasing
severe potential, with all-hazards possible.

Day 7/Sunday, eastward advance of the synoptic-scale features will
continue, along with some continued strengthening. With continued
moistening of the pre-frontal warm sector supporting afternoon
destabilization, along with increasing deep-layer flow, a broad area
of severe risk seems likely to evolve -- centered over the Mid and
Lower Mississippi/Lower Ohio/Tennessee Valleys. Again -- all severe
weather hazards would be possible.

Monday, the primary focus for convective potential will shift east
of the Appalachians. Here, weaker low-level moisture (and thus less
robust destabilization potential) is expected at this time.
Therefore, while severe risk may evolve, thermodynamic uncertainty
precludes initiation of a risk area for Day 8/Monday.

..Goss.. 03/24/2025

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ACUS48 KWNS 250911
SWOD48
SPC AC 250909

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0409 AM CDT Tue Mar 25 2025

Valid 281200Z - 021200Z

...DISCUSSION...
Medium-range models appear to be in reasonably good agreement into
the Day 7 period (Monday March 31), with respect to
evolution/progression of large-scale features.

Day 4/Friday, a southern-stream trough is forecast to continue
moving slowly eastward across the south-central states, reaching the
lower Mississippi Valley Saturday morning. Showers and
thunderstorms will accompany this feature, but the lack of robust
CAPE/shear likely to be associated with this feature suggests that
severe potential should remain subdued.

Farther north, weak disturbances moving through anticyclonic flow
aloft across the Upper Midwest/Upper Great Lakes/Ohio Valley will
likely combine with warm advection near the northward-advancing warm
front to support areas of deep convection, with some potential for
hail. Risk however appears too low to warrant an areal inclusion.


Saturday (Day 5), an upper trough will continue advancing across the
Rockies. However, models forecast the main surface low to remain
over the eastern Colorado vicinity into the evening hours, with a
capped warm sector residing across eastern Kansas/Oklahoma/Texas and
the Ozarks area (i.e. yesterday's Day 6 outlook area) in a zone of
subsidence in the wake of the slow-moving southern-stream trough.
As such, storm initiation now appears likely to remain largely
hindered through Sunday morning.

The primary severe risk appears likely to evolve Sunday/Day 6, from Missouri/Arkansas/northern Louisiana, spreading eastward through the
day, and eventually approaching the west slopes of the Appalachians.
As the western U.S. upper trough emerges into the Plains,
supporting deepening of surface low pressure, a moist warm sector
will destabilize through the day, likely yielding storm development
initially west of the Mississippi Valley, and then spreading
eastward through the evening. The favorable thermodynamic
environment will combine with strong/veering flow through the middle troposphere, suggesting of severe storms including supercells, and
attendant, all-hazards severe potential.

By Monday, models begin to diverge with respect to speed of
surface-frontal advancement east of the Appalachians. Still, enough destabilization should occur east and southeast of the front to
allow storms to spread across the Southeast, along with attendant
severe risk.

Tuesday, model differences continue to increase, with the front
residing off the Atlantic and Gulf Coasts per the GFS, while
lingering over parts of the Southeast and the Gulf Coast region per
the ECMWF. Given the uncertainty/predictability issues, no risk
areas will be included.

..Goss.. 03/25/2025

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ACUS48 KWNS 260906
SWOD48
SPC AC 260904

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0404 AM CDT Wed Mar 26 2025

Valid 291200Z - 031200Z

...DISCUSSION...
Medium-range models appear to be in reasonable agreement through Day
6 (Monday March 31), with respect to synoptic-scale features.
Divergence in solutions increases thereafter, particularly with the strength/progression of the next trough moving across the western
CONUS and into the Plains. As such, no risk areas will be
considered beyond Day 6/Monday.

Day 4/Saturday, a couple of small-scale vorticity maxima/short-wave
troughs are forecast to cross the central portion of the country,
ahead of the stronger system advancing across the West. This
feature is forecast to reach the High Plains overnight, as a surface
low moves across the Kansas/Oklahoma vicinity. Models continue to
indicate that capping will remain an issue, hindering convective
development in the warm sector ahead of the low (across the Kansas/Oklahoma/western Missouri/western Arkansas area) at least
until after dark/overnight. While some severe threat may evolve
with storms which should be slightly elevated for the most part,
risk does not appear sufficient to warrant inclusion of a 15% risk
area.

Day 5/Sunday, more substantial cyclogenesis is expected, though
differences exist between the models in terms of timing/location of
the developing low -- and associated cold front. Nonetheless,
substantial warm-sector destabilization is forecast to occur from Missouri/Arkansas/eastern Texas eastward across the Mississippi
Valley during the day, and extending eastward across the
Midwest/Ohio and Tennessee Valleys. This will support scattered
thunderstorm development, within an increasingly sheared
environment. By early afternoon, severe/supercell storms are
expected, accompanied by the risk for very large hail, damaging
winds, and a few tornadoes. Storms should spread southeast of the
Ohio and Mississippi Valleys overnight, accompanied by ongoing
severe risk.

Day 6/Monday, risk will likely have shifted to near and east of the Appalachians, and southward to the Gulf Coast area, as the surface
cold front advances. Destabilization ahead of the front will
support continuation of severe risk given favorably strong flow
aloft, with storms reaching/moving off the Gulf and Atlantic Coasts
late in the period.

..Goss.. 03/26/2025

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ACUS48 KWNS 270859
SWOD48
SPC AC 270857

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0357 AM CDT Thu Mar 27 2025

Valid 301200Z - 041200Z

...DISCUSSION...
Predictability remains a concern during the medium-range period.
Models reveal notable differences even in the Day 4-5 time frame
with respect to strength of the eastern U.S. upper trough, and
associated evolution/development of the surface pattern. As the
initial surface system moves offshore late in the Day 5 period
(Tuesday morning), substantial divergence in solutions is evident
with the next trough moving into/across the western CONUS. Given
these differences, any severe potential beyond Day 5 cannot be
quantified with any degree of confidence.

With that said, a fairly widespread area of severe potential remains
evident Day 4/Sunday, ahead of a cold front moving eastward across
the Mississippi and Ohio and eventually the Tennessee Valleys.
Northward advection of 60s dewpoints is expected ahead of this
front, which will combine with daytime heating to boost mixed-layer
CAPE into the 1000 to 1500 J/kg range, and potentially above 2000
J/kg farther southwestward along the front from East Texas into the
lower Mississippi Valley.

As a belt of strong southwesterly flow aloft overspreads the moistening/destabilizing pre-frontal boundary layer, development of strong/severe storms is expected near and ahead of the boundary
during the afternoon -- potentially extending as far southwestward
as East Texas. Along with potential for large hail and damaging
winds, likelihood for supercell storms suggests potential for a few
tornadoes as well. Risk will spread eastward through the evening
across portions of the Midwest/Ohio Valley and Mid/Lower Mississippi
Valley, and southeastward into the Tennessee Valley and central Gulf
Coast states overnight -- likely persisting through the end of the
period.

Day 5/Monday, models begin to differ more substantially with respect
to surface frontal location -- particularly with northern extent.
The GFS depicts the front as extending from New England
southwestward to the Texas Coast Monday morning, while the ECMWF
places it from Lower Michigan to coastal Texas. By late afternoon,
the GFS shows the front reaching the New England coastal area and
Mid-Atlantic region, focusing the primary severe threat from the
Mid-Atlantic area southwestward. Meanwhile, some risk could extend
as far north as the Lower Great Lakes region/central Appalachians
per the ECMWF's deterministic forecast. At this time, will keep the
Day 5 risk area focused from the Mid-Atlantic region to the lower
Mississippi Valley, though adjustments/refinements to the area over
the next several days will likely be required.

..Goss.. 03/27/2025

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ACUS48 KWNS 280902
SWOD48
SPC AC 280900

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0400 AM CDT Fri Mar 28 2025

Valid 311200Z - 051200Z

...DISCUSSION...
Widespread storms and at least some attendant severe risk will be
ongoing at the start of the Day 4 period (Monday March 31) -- with
the band of convection likely extending along the west slopes of the Appalachians initially. Diurnal destabilization along and east of
the mountains remains a question, particularly with northward extent
into the Northeast, and thus the northern periphery of the risk area
remains in question -- in what will likely be a very low CAPE/high
shear environment -- suggestive of damaging gusts being the primary
concern over northern portions of the area.

Farther south, greater CAPE is expected, particularly from the
Carolinas into the central Gulf Coast states. Here, an all-hazards
risk is forecast to continue from the Day 3 period into Day 4.
Storms/severe risk will shift eastward with time, crossing the East
Coast states through the afternoon and evening, before clearing the
coast overnight.

Day 5/Tuesday looks to be a relative down day in terms of severe
potential, with moisture beginning to return northward into the
central U.S. ahead of the next system.

Day 6/Wednesday, moisture will continue returning northward across
the central U.S., though substantial differences in timing/evolution
of the upper system exists between the (slower) ECMWF and (faster)
GFS. However, the GEFS ensemble mean is slower than the operational
GFS, not quite as slow as but more in line with the ECMWF -- and the
Euro ensemble mean. Given this, confidence is high enough to
proceed with introduction of a broad -- though areally uncertain --
15% area. This system would appear to have the potential to produce
another fairly widespread/all-hazards severe event, but will likely
require a good bit of adjustment over the next few days.

Beyond Day 6, confidence in evolution of the large-scale features
diminishes further, due to the aforementioned differences between
operations runs of the global models. As such, no areas will be
delineated beyond Day 6.

..Goss.. 03/28/2025

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ACUS48 KWNS 280910
SWOD48
SPC AC 280909

Day 4-8 Convective Outlook CORR 1
NWS Storm Prediction Center Norman OK
0409 AM CDT Fri Mar 28 2025

Valid 311200Z - 051200Z

CORRECTED GRAPHIC

...DISCUSSION...
Widespread storms and at least some attendant severe risk will be
ongoing at the start of the Day 4 period (Monday March 31) -- with
the band of convection likely extending along the west slopes of the Appalachians initially. Diurnal destabilization along and east of
the mountains remains a question, particularly with northward extent
into the Northeast, and thus the northern periphery of the risk area
remains in question -- in what will likely be a very low CAPE/high
shear environment -- suggestive of damaging gusts being the primary
concern over northern portions of the area.

Farther south, greater CAPE is expected, particularly from the
Carolinas into the central Gulf Coast states. Here, an all-hazards
risk is forecast to continue from the Day 3 period into Day 4.
Storms/severe risk will shift eastward with time, crossing the East
Coast states through the afternoon and evening, before clearing the
coast overnight.

Day 5/Tuesday looks to be a relative down day in terms of severe
potential, with moisture beginning to return northward into the
central U.S. ahead of the next system.

Day 6/Wednesday, moisture will continue returning northward across
the central U.S., though substantial differences in timing/evolution
of the upper system exists between the (slower) ECMWF and (faster)
GFS. However, the GEFS ensemble mean is slower than the operational
GFS, not quite as slow as but more in line with the ECMWF -- and the
Euro ensemble mean. Given this, confidence is high enough to
proceed with introduction of a broad -- though areally uncertain --
15% area. This system would appear to have the potential to produce
another fairly widespread/all-hazards severe event, but will likely
require a good bit of adjustment over the next few days.

Beyond Day 6, confidence in evolution of the large-scale features
diminishes further, due to the aforementioned differences between
operations runs of the global models. As such, no areas will be
delineated beyond Day 6.

..Goss.. 03/28/2025

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ACUS48 KWNS 290903
SWOD48
SPC AC 290902

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0402 AM CDT Sat Mar 29 2025

Valid 011200Z - 061200Z

...DISCUSSION...
Medium-range models appear to be in fairly good agreement through
much of the medium-range period, with respect to large-scale pattern evolution/placement of the main synoptic-scale features. One
primary difference between the GFS and ECMWF at this time is that
the EC is more highly amplified with the upper pattern through the
period, and thus -- in general -- depicting stronger surface
features and greater flow aloft/wind shear.

One result of the higher amplitude of the ECMWF manifests Day
4/Tuesday April 1. As the eastern U.S. trough moves off the
Atlantic Coast, and the cold front stalls over the northern Gulf of
America early, northward return of this boundary as a warm front is
forecast over the southern and eventually the central Plains.
Central High Plains cyclogenesis is expected along this front as it
shifts northward. However, given the more amplified nature of
western troughing within the ECMWF, a much stronger surface cyclone
is progged by the EC as compared to the GFS (984 mb vs. 991 mb
respectively). The result is much stronger low-level theta-e
advection across the central/southern Plains depicted by the EC,
driving a much more rapid northward advance of the warm front. Both
models suggest after-dark convective development, but where the GFS
depicts weaker, elevated CAPE across Kansas, the EC's more robust,
potentially near surface-based CAPE suggests greater, more
widespread severe potential than the GFS. At this time, a small 15%
area will be introduced, centered over the mid Missouri Valley area,
mainly for the potential for hail with stronger storms. Later
refinements of the risk area will likely be required.

Day 5/Wednesday, a widespread, potentially substantial severe event
remains apparent, and with greater agreement within the models with
respect to the upper trough advance and associated positioning of
the surface low/cold front, greater confidence with respect to the
degree of risk exists. While a very similar 15% risk area will be
depicted as in yesterday's outlook, a 30% area is being introduced
from Arkansas northeastward to the mid Ohio Valley. It appears that
the environment will become conducive for supercells, with very
large hail, damaging winds, and strong tornadoes all possible during
the afternoon and evening hours.

From Day 6 onward, the cold front will continue its eastward advance
across the Ohio Valley and into/across the Northeast/New England.
However, much slower southward progression of the cold front is
expected, with an eventual drift northward as a warm front that then lingers/oscillates across the Ohio Valley/Mid South/central and
southern Plains through the end of the period. This will occur as
a slow-moving trough moves into the West, and eventually evolves
into a cut-off low. While weak disturbances eject eastward through southwesterly flow aloft across the central U.S. -- each of which
may bring rounds of convection/severe potential in the day 6-8 time
frame, narrowing down specific/greater areas of potential is
difficult at this time.

..Goss.. 03/29/2025

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ACUS48 KWNS 300901
SWOD48
SPC AC 300859

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0359 AM CDT Sun Mar 30 2025

Valid 021200Z - 071200Z

...SEVERE WEATHER OUTBREAK POSSIBLE ON D4/WED...

...DISCUSSION...
Medium-range models appear to be in good agreement with overall
evolution of the synoptic-scale pattern into the Day 7 (Saturday
April 5) time period, when divergence in solutions increases.

Earlier in the period however, model consistency lends fairly high
confidence that a widespread/potentially substantial outbreak of
severe weather will evolve Wednesday/Day 4, from Lower Michigan and
the Ohio Valley, southwestward across the Middle and Lower
Mississippi Valleys, and into eastern portions of Texas and
Oklahoma. Convection will likely be ongoing or developing early in
the day, over western portions of the risk area -- from Wisconsin
southwestward to Oklahoma/North Texas. As an upper low shifts
northeastward across the northern Plains toward the upper
Mississippi Valley through the day, and the cold front crosses Iowa/Missouri/eastern Oklahoma, steep lapse rates atop a
moist/diurnally heating warm sector will support widespread
convective development.

With ascent along the front somewhat modest as stronger large-scale
ascent focuses northward into the western Upper Great Lakes and into
Ontario, storm mode may tend toward isolated storms, as opposed to
more linear development. This, combined with flow that is forecast
to weakly veer but dramatically strengthen with height, suggests a
primarily supercell storm mode. In additional to very large hail
(particularly with southward extent), widespread damaging winds and
several tornadoes are expected, some possibly significant. Risk is
expected to continue well into the evening and likely overnight,
shifting slowly eastward across the Midwest and mid/lower
Mississippi Valley through the end of the period.

Day 5/Thursday, trailing portions of the cold front should become
aligned east-northeast to west-southwest across the Ohio and mid
Mississippi Valleys and into the southern Plains, as the upper
system shifts quickly across eastern Canada. While weak short-wave
ridging will evolve atop the surface frontal zone in the wake of the
departing system, daytime heating of a very moist boundary layer
along and south of the front combined with strong flow aloft will
support reinvigorated convection through the afternoon and evening
hours, along with attendant severe-weather risk.

Day 6/Friday, the surface front should remain quasi-stationary, but
short-wave ridging should increase as a cut-off low evolves across
the West. As such, much of the Day 6 convection may occur to the
cool side of the surface front, in the zone of warm
advection/isentropic ascent. While some severe risk will likely
evolve, mainly in the form of hail, uncertainty overall (given the
ridging aloft) precludes inclusion of a Day 6 risk area.

By the weekend, deviation in model solutions increases, due to
uncertain evolution of the low/trough over the West. As such, no
risk areas will be included.

..Goss.. 03/30/2025

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ACUS48 KWNS 310900
SWOD48
SPC AC 310859

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0359 AM CDT Mon Mar 31 2025

Valid 031200Z - 081200Z

...DISCUSSION...
Active and progressive mid-level flow will persist across the CONUS
as a large upper trough moves from the Great Lakes into eastern
Canada. Several additional troughs, embedded within strong
west/southwesterly flow aloft, will move over the lower 48 through
the next week. Deep moisture and strong mid-level flow overlapping
will favor severe potential across the southern Plains, Mid MS/OH
Valleys and the Eastern CONUS through the extended forecast period.

...D4/Thursday...
As the primary upper trough departs to the northeast, the cold front
will stall across the OH/MS Valleys and into the southern Plains. A
secondary trough embedded within the southwesterly flow will emerge
over the southern Rockies and lift over the southern/central Plains.
A surface low, with trailing dryline and the stationary front, will
focus convective development through the afternoon and evening. The
broad warm sector, ample moisture, and steep mid-level lapse rates
will support moderate to strong instability, overlapping with robust
deep-layer shear. Severe thunderstorms appear likely from Northeast
TX, through AR/LA and into the Mid MS/OH Valleys.

Additionally, some severe risk may develop over parts of the Mid
Atlantic as the cold front slowly approaches from the northwest.
Relatively strong flow aloft may overlap with an increasingly moist
airmass, supporting some potential for storms with a wind/hail risk.
However, weak shortwave ridging, and multiple preceding days of
thunderstorm potential casts considerable uncertainty on the
potential for storms and the positioning of the front/quality of the
low-level airmass.

...D5/Friday...
The upper-level pattern begins to change D5/Friday as an upper low
is forecast to emerge across parts of the Southern Plains and
northern Mexico. Deep meridional flow will overspread parts of TX,
OK and AR while the front begins to sag south across the MS and OH
Valleys. Some supercell risk may develop across the Red River
vicinity and across the mid MS Valley near the stalled front.
However, the surface picture remains very complicated due to
multiple preceding days of convective potential.

...D6/Saturday and beyond...
Confidence in the upper-level evolution diminishes D6/Saturday and
through the weekend, as the projected upper low begins moving
eastward. Increasing high pressure over the northern US may begin to
suppress the northward extent of the deeper surface moisture. While
some severe risk may exist given relatively strong mid-level flow
near the stalled front from the ArkLaTex eastward into the
Southeast, model solutions vary greatly on the affected area and
associated hazards. Confidence is too low to initiate severe
probabilities.

..Lyons/Goss.. 03/31/2025

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ACUS48 KWNS 010859
SWOD48
SPC AC 010857

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0357 AM CDT Tue Apr 01 2025

Valid 041200Z - 091200Z

...DISCUSSION...
Amplified mid-level flow and deep moisture south of a quasi
stationary frontal zone will persist over much of the central and
eastern CONUS through the first half of the extended forecast
period. Models are in generally good agreement with the progression
of the pattern and the potential for severe storms. However, some
key differences, and days of preceding convection will modulate
potential in the coming days.

...Day4/Friday...
The broad upper trough over the western US is forecast to gradually
deepen Friday into the weekend, as an upper low forms over northern
Mexico. Flow aloft will become increasingly southerly over the
southern Plains while it curves anticyclonically over the Mid South
and eastern US. A rich pool of deep moisture will continue to reside
along a quasi stationary frontal zone from the Red River to the OH
Valley. Several clusters of strong to severe storms appear possible
within the broadly favorable zone of weak ascent and large
buoyancy/shear. The surface picture remains very complicated due to
multiple preceding days of convective potential.

...Day5/Saturday...
The primary mid-level impulse will begin to eject across northern
Mexico, eventually reaching the lower/middle MS Valley D5/Saturday.
Model differences begin to emerge on the latitudinal extent of the
warm sector owing to differences in the timing/structure of the
ejecting upper cyclone. Regardless, continued southerly low-level
flow will replenish deep moisture over much of the ArkLaTex and
Southeastern US. A surface low and cold front will gradually
intensify across the Mid South, likely focusing severe potential
ahead of it. The intensity of the severe risk will likely be tied to
ongoing storms from the prior Day 4, but supercells are possible
from east TX into the MS Valley and parts of the Southeast into
Saturday night.

...Day6-8...
The cold front and low will continue to move eastward with the upper
trough through the end of the weekend and into early next week. Some
severe risk could emerge over parts of the Southeast/eastern US with
seasonably high moisture and instability. However, model differences
on the frontal timing and the potential for multiple rounds of
proceeding convection make severe potential very uncertain beyond
Day 5.

..Lyons.. 04/01/2025

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ACUS48 KWNS 020902
SWOD48
SPC AC 020900

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0400 AM CDT Wed Apr 02 2025

Valid 051200Z - 101200Z

...DISCUSSION...
The mid-level flow pattern will undergo significant amplification
over the next several days as a large western US trough begins to
move eastward. Very rich moisture will support widespread
thunderstorm potential across parts of the Southeast and eastern US
through the weekend.

...D4/Saturday Mid South...
The upper low over northern Mexico will continue to amplify as it
begins ejecting eastward across the lower and mid MS Valley. A
strong 100+ kt jet will move east of the trough and overspread a
relatively broad warm sector across the Sabine and MS Valleys into
parts of TN/KY. Unseasonably rich moisture from several days of
southerly flow will be in place ahead of a surface low and cold
front. One or more rounds of severe storms, including supercells,
appears likely from eastern TX into AR, LA, and MS through the day.
All hazards will be possible. Storms should eventually grow upscale
into a line or cluster and spread eastward overnight into parts of
AL, FL, and GA.

The northern bound of the risk area across the TN Valley and into
the OH valley appears somewhat conditional. Multiple preceding days
of storms may limit the northern extent of the deeper moisture and
buoyancy. However, some severe risk likely exists given the
intensity of the low-level jet and abundance of moisture.

...Day 5...
The severe threat is likely to carry over from Day 4 in the form of
a squall line, as the upper wave gradually devolves into a broader positive-tilt trough. Strong mid-level flow and ascent will persist
over a broadening warm sector across the Southeast. While lapse
rates appear weak from several days of convection, some severe risk
is possible. The intensity of the severe risk will be heavily
dependent on the convective evolution from the prior day 4 which is
very unclear at the moment. Will add a 15% area across parts of AL,
FL, GA and SC where the best overlap of mid-level flow and robust
moisture are expected to support potential for damaging gusts.

A severe risk may also develop across parts of the Carolinas and mid
Atlantic Day5/Sunday. As the upper wave lifts to the north, ascent
will overspread returning surface moisture as far north as southern
PA. It is unclear how much buoyancy will be present with the
potential for widespread clouds. However, strong flow fields will be
available to any convection that can develop.

...D6+...
Offshore flow and high pressure will begin to dominate the extended
period as mid-level ridging intensifies over the center of the
country. Much cooler and stable conditions behind the advancing cold
front appear likely to temporarily end broader potential for severe
storms through early next week.

..Lyons.. 04/02/2025

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ACUS48 KWNS 030824
SWOD48
SPC AC 030822

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0322 AM CDT Thu Apr 03 2025

Valid 061200Z - 111200Z

...DISCUSSION...
Models are in relatively good agreement for the Sunday/D4 to
Monday/D5 period, depicting an elongating upper trough sweeping east
from the OH/TN Valleys to the East Coast.

On Sunday/D4, a leading midlevel wave is forecast to move out of AR
and across TN/KY, with little amplitude and poor lapse rates by this
time. An extensive area of rain and thunderstorms will be ongoing
along the length of the cold front throughout the day, from the
Northeast to the northern Gulf Coast. Some severe wind threat is
expected, mainly over parts of the Southeast where dewpoints will be
higher and as deep-layer shear remains favorable.

The trend of widespread precipitation along this front will continue
into early Monday/D5, from the Carolinas into FL. The severe risk
should continue to dwindle as large-scale support weakens, but
low-end potential cannot be ruled out over these areas.

For the Tuesday/D6 to Thursday/D8 time frame, the weather pattern
will be much less conducive to severe storms, with a ridge building
over the West, and northwest flow across the central states.
Periodic surges of high pressure are forecast, helping to keep
conditions mostly stable over the bulk of the CONUS.

..Jewell.. 04/03/2025

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