Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1226 AM CDT Tue Sep 15 2026
Valid 151200Z - 161200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE
SOUTH-CENTRAL PLAINS INTO PARTS OF 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.
...South-central Plains into parts of the Midwest...
A vigorous mid/upper-level trough will move quickly eastward across
Ontario and the Upper Great Lakes region today, before reaching
southern Hudson Bay and Quebec by this evening. A deep surface low
will accompany this system, as a trailing cold front moves across
parts of the central Plains and Midwest. To the south of the
ejecting trough, an upper ridge is forecast to amplify over the
Southeast.
Persistent clouds and precipitation to the cool side of the front
will help to reinforce the baroclinic zone as it moves southeastward
through the day. The front will impinge on an increasingly warm and
unstable environment by late afternoon, and scattered storm
development is expected from the TX Panhandle into parts of the
Midwest. The strongest mid/upper-level flow will be displaced north
of the front, and low-level flow will tend to weaken through the
day.
This weakening flow regime, combined with gradual midlevel height
rises and an eventual tendency for storms to be undercut by the
front, results in uncertainty regarding the magnitude of the
organized severe threat this afternoon and evening. However,
seasonably strong heating and relatively large PW and buoyancy will
support potential for localized downbursts and outflow-driven
clusters, with attendant damaging-wind potential. Hail potential
appears generally limited by weak midlevel lapse rates and only
modest deep-layer shear, though small to near-severe hail may occur
with the strongest cells.
A relatively broad Marginal Risk has been maintained from the
south-central Plains into the Midwest. Corridors of locally greater
potential could eventually evolve within the broader risk area,
especially near any pre-frontal outflow boundaries generated by
early-day convection.
...Parts of UT/western CO...
Anomalous moisture will remain in place across parts of the Four
Corners region and Southwest today. The strongest deep-layer
flow/shear will reside from UT into western CO, in advance of a
mid/upper-level trough over the Pacific Northwest. While a few
strong storms will be possible, generally weak heating and
destabilization are currently expected to limit the magnitude of the
severe threat. Small hail and gusty winds could accompany the
strongest storms.
..Dean/Supinie.. 09/15/2026
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