Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0800 PM CDT Sun Sep 20 2026
Valid 210100Z - 211200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL HIGH PLAINS....
...SUMMARY...
Thunderstorms with large hail and severe wind gusts will be possible
this evening across parts of the central High Plains. A few severe
wind gusts may also occur from the Ozarks northeastward into the
Ohio Valley.
...Central High Plains...
The latest water vapor imagery shows a shortwave mid-level trough
over eastern Colorado. An axis of moderate instability, with MLCAPE
in the 1500 to 2000 J/kg range, is analyzed by the RAP just ahead of
this feature from near the Colorado-Kansas state line southeastward
into the Oklahoma Panhandle. An isolated supercell is currently
ongoing near the instability axis near Lamar, Colorado. RAP forecast
soundings ahead of this cell across far southwest Kansas early this
evening have MLCAPE in the 1500 to 2000 J/kg range, 0-6 km shear
near 40 knots and 700-500 mb lapse rates around 7 C/km. This
environment will continue to support supercells capable of large
hail and wind damage. The threat could persist into the mid to late
evening with parts of southwest Kansas and the Oklahoma Panhandle
being affected. Later this evening, short-term model forecasts also
suggest that redevelopment may occur to the east of the Denver
Metro, with a new cluster potentially tracking southeastward near
the instability axis. This activity could also pose a large hail and
wind damage threat.
...Ozarks into the Ohio Valley...
Several minor perturbations, embedded in westerly flow aloft, appear
to moving through a corridor from the Ozarks eastward into the Ohio
Valley. The most pronounced feature appears to be located in
southeastern Indiana, ahead of which a small cluster of severe
storms is ongoing. Along the projected track of these storms, the
RAP has MLCAPE in the 1200 to 1500 J/kg range with 0-6 km around 35
knots. This should continue to support an isolated wind-damage
threat for a couple more hours early this evening...see MCD 2319.
Further southwest into the parts of the Ozarks and mid Mississippi
Valley, moderate instability is analyzed by the RAP from far
northeast Oklahoma northeastward into south-central Illinois.
Isolated to scattered thunderstorms are ongoing near the instability
axis. These storms may be capable of producing isolated severe wind
gusts for another hour or two this evening...see MCD 2318.
..Broyles.. 09/21/2026
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