ACUS01 KWNS 151230
SWODY1
SPC AC 151228

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0728 AM CDT Tue Sep 15 2026

Valid 151300Z - 161200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHERN/CENTRAL PLAINS INTO THE MIDWEST...

...SUMMARY...
Strong to locally severe thunderstorms may occur from the
south-central Plains into parts of the Midwest this afternoon and
evening, with at least isolated damaging wind gusts possible.

...Southern/Central Plains into the Midwest/Great Lakes...
The primary mid/upper-level trough over central/eastern Canada will
remain displaced well north of the surface warm sector today, with
upper ridging remaining anchored over the Southeast. A surface cold
front will make generally slow south-southeastward progress over the
central Plains and mid MS Valley/Midwest through this evening,
before eventually stalling late in the period. A seasonably moist
airmass characterized by surface dewpoints in the 60s to low 70s
will be in place ahead of the front from the southern High Plains
northeastward to the southern Great Lakes vicinity. While lapse
rates aloft will remain modest, daytime heating will support the
development of moderate instability by mid afternoon along much of
the length of the front (perhaps locally stronger across parts of
eastern KS into MO/IL).

Enhanced mid-level flow will tend to remain north of the cold front,
but some veering and gradual strengthening of the wind field with
height through mid levels should support sufficient deep-layer shear
for modest updraft organization, especially from parts of the
central Plains into the Midwest. Current expectations are for
thunderstorms to gradually develop by 20-23Z along/near much of the
length of the front as convective temperatures are reached. Loosely
organized clusters capable of producing mainly damaging winds should
be the primary concern as this convection spreads generally
east-northeastward through the evening, especially where low-level
lapse rates can become steepened. This appears more likely across
parts of the southern/central Plains where stronger heating is
forecast. Some chance for marginal supercell structures may exist
from parts of eastern KS into MO this afternoon, with isolated hail
possible. Considered greater wind probabilities and a Slight Risk
across this region, but potential for an organized cluster remains
too uncertain for an upgrade with this update.

...Southwest/Four Corners...
A rather moist low-level airmass (surface dewpoints generally in the
50s) will remain across parts of the Four Corners region today.
Modestly enhanced west-southwesterly mid-level flow will persist
from UT into western CO ahead of a mid/upper-level trough over the
Pacific Northwest. While occasional strong thunderstorms appear
possible, modest heating and overall weak destabilization are
currently expected to limit the magnitude of the severe threat.
Small hail and gusty winds could accompany the strongest cores, but
confidence in organized severe thunderstorms remains too low to
include any hail/wind probabilities at this time.

..Gleason/Mead.. 09/15/2026

$$
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