Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0745 AM CDT Wed Aug 26 2026

Valid 261300Z - 271200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHERN GREAT LAKES/MIDWEST...CENTRAL HIGH PLAINS...AND
OZARKS/MID-SOUTH INTO THE LOWER MISSISSIPPI VALLEY...

...SUMMARY...
Isolated to widely scattered severe thunderstorms are forecast today
across parts of the southern Great Lakes into the Midwest,
central/southern High Plains, and the Ozarks into the Mid-South and
Lower Mississippi Valley. Severe/damaging winds should be the main
threat across these regions, though large hail is also possible,
particularly across the central High Plains.

...Southern Great Lakes into the Midwest...
A mid-level shortwave trough over the upper Great Lakes this morning
will progress eastward today across southern Ontario. The basal
portion of this trough will overspread parts of the southern Great
Lakes and Midwest, with a surface cold front moving
east-southeastward across these regions as well. Lapse rates aloft
are forecast to remain rather poor, which may tend to limit updraft
strength to some extent. Still, a corridor of destabilization is
expected along/ahead of the front through the afternoon, with at
least moderate instability likely from eastern IL northeastward into
southern Lower MI. Thunderstorms should develop along/ahead of the
front as convective temperatures are reached by 19-22Z.
Low/mid-level winds will tend to remain fairly modest and veered to
westerly, with up to 25-35 kt of deep-layer shear fostering some
updraft organization.

A mix of multicell clusters and marginal supercells should pose a
threat for both hail and damaging winds, with the wind threat
potentially becoming the primary risk with eastward extent into the
Midwest as thunderstorms grow upscale. A brief embedded tornado may
also occur, but low-level flow is forecast to remain rather veered,
with limited hodograph curvature noted in most NAM/RAP forecast
soundings. The overall severe threat will likely diminish quickly
this evening as convection outpaces the low-level
moisture/instability, and as nocturnal cooling of the boundary layer
occurs.

...Ozarks into the Mid-South and Lower Mississippi Valley...
Thunderstorms have developed this morning across southeast MO/far
southern IL, and they should continue to track south-southeastward
into the Mid-South along the MUCAPE gradient noted in latest
mesoanalysis. While sub-severe for now given substantial MLCIN
present, there is some potential for this activity to persist and
eventually strengthen later today across parts of western TN into
northern MS and vicinity as the boundary layer gradually
destabilizes. Have adjusted/expanded wind probabilities a bit
eastward in western TN/northern MS into northern/central AL to
account for this possibility.

Otherwise, additional thunderstorm development is also likely this
afternoon along/near a weak surface front from southern MO into AR
and eastern OK. This activity may be aided by a remnant MCV that
will move eastward across the southern Plains through the day.
Modest deep-layer shear should support some updraft organization,
with multicell clusters likely the dominant mode. High total
precipitable water values and large buoyancy will support robust
downbursts with primarily a scattered damaging wind threat.
Occasional hail may also occur with the strongest cores given the
degree of instability forecast. Some high-resolution guidance
continues to show a southward-moving storm cluster across the lower
MS Valley this evening/tonight. As such, there is potential for at
least isolated damaging winds to persist across parts of southern
LA/MS.

...Central/Southern High Plains...
Around 25-35 kt of west-northwesterly mid-level flow will be present
over the southern/central High Plains today, with a mid/upper-level
ridge remaining centered over the Southwest/Four Corners. Modest
low-level upslope flow across the central High Plains should support
convective initiation by early/mid afternoon over the higher terrain
and Front Range. Moderate instability aided by modestly steepened
mid-level lapse rates and sufficient deep-layer shear should all act
to aid updraft organization, with both supercells and clusters
possible. There is still some uncertainty with convective
development farther east across southwest NE this afternoon
along/near a front. But, any thunderstorms that can form and persist
across this area would also pose a severe risk. Both large hail and
severe gusts may occur with convection that spreads
east-southeastward through the afternoon and evening, with some
potential for upscale growth/additional clustering into western KS
this evening.

Farther south across the southern High Plains, mid-level flow and
related deep-layer shear should be somewhat weaker. Still,
convection that develops across central into eastern NM may become
loosely organized while posing an isolated threat for severe gusts
given the presence of a very well-mixed boundary layer. This threat
may continue into parts of the OK/TX Panhandles and west TX through
the evening before eventually weakening.

..Gleason/Broyles.. 08/26/2026

Day 4-8 Convective Outlook  
NWS Storm Prediction Center Norman OK
0342 AM CDT Wed Aug 26 2026

Valid 291200Z - 031200Z

...DISCUSSION...
...D4/Saturday - Northern Plains to Upper Midwest...
A mid-level ridge will move slowly east across the Plains with
slight suppression through the day. A lee trough will consolidate
into a surface low across the northern Plains through the day
Saturday. Ahead of this surface low, strong instability is forecast
across South Dakota and vicinity. Despite the favorable environment
across this region, primary forcing will be focused on the nose of
the low-level jet across Iowa and into Wisconsin, well east of the
greatest instability and near the Canadian border. Therefore,
limited storm coverage precludes severe weather probabilities at
this time, but given the favorable environment, it will need to be
monitored closely. 

...D5/Sunday - North Dakota and Vicinity...
A mid-level shortwave trough will move from the Pacific Northwest to
the northern Plains Saturday/D4 and Sunday/D5. 00Z guidance has come
into fairly consistent agreement with the location and amplitude of
this trough across eastern Montana at 00Z Sunday evening. However,
there is considerable disagreement with the degree of
destabilization across North Dakota, where forcing will be greatest.
The GFS dry bias across most of the Plains has severely lessened the
instability. However, despite this challenge, it is apparent that
most of the instability significantly southeast of the upper-level
forcing. The GFS-Para seems to have a more realistic handle on
low-level moisture/instability magnitude but it also shows a
significant disconnect between where this instability is located and
the deeper forcing. 

The deterministic ECMWF forecast shows a potentially significant
severe weather event across North Dakota with strong instability and
shear ahead of a robust convective QPF signal. This is supported by
the AI-ECMWF which shows a similar evolution. However, the
EC-ensemble mean of instability shows at least some trend toward the
GEFS with primary instability southeast of the best forcing. 

It is also worth noting that the wave is forecast to eject across
North Dakota relatively late (~06Z) which may be a somewhat limiting
factor to a greater threat. This potential timing disconnect,
combined with some hint of limited overlap between the greatest
instability and the primary upper forcing, cast enough uncertainty
to preclude severe weather probabilities at this time. However, it
is worth noting that if a solution similar to the ECMWF
materializes, a significant severe weather event is possible. 

...D6 and Beyond...
By early next week, the primary mid-level ridge appears to center
around the southern Appalachians with broad southwesterly flow from
the Southwest to the Great Lakes. Within this area of southwesterly
flow, multiple embedded mid-level shortwave troughs are forecast.
Predictability of these smaller scale features is relatively low at
this range, but some continued severe weather threat will likely
persist around the periphery of the ridge from the Plains to the
Great Lakes and potentially into the Northeast.