Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1252 AM CDT Sun Sep 27 2026

Valid 271200Z - 281200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS PORTIONS OF THE
CENTRAL AND NORTHERN HIGH PLAINS...

...SUMMARY...
Isolated thunderstorms capable of large hail will be possible across
portions of western Nebraska and the Black Hills of South Dakota.

... Synopsis ...

The midlevel pattern across the CONUS today will feature a nearly
stationary occluding cyclone southeast of Long Island, broad
anticyclonic flow across the middle of the country, and a deep
trough moving into northern and central California. Additionally, a
subtle vorticity maxima is forecast to lift quickly from near the
southern California coast toward the northern Plains. 


... Portions of the Central and Northern High Plains ...

Diurnal heating of a seasonably moist airmass will result in between
1000-2000 J/kg of SBCAPE during the afternoon. The atmosphere is
likely to be capped during the afternoon, although an isolated
thunderstorm or two are possible. Large hail and strong thunderstorm
winds will be possible with any surface-based thunderstorms that do
develop. During the evening, thunderstorm coverage may increase in
response to increasing large-scale ascent associated with the
approaching subtle vorticity maxima and an increase in the low-level
jet. Large hail will be possible with the strongest of these storms.

..Marsh.. 09/27/2026

Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1256 AM CDT Sun Sep 27 2026

Valid 281200Z - 291200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not forecast across the U.S. on Monday or
Monday night.

...DISCUSSION...
At mid-levels, a ridge will be in place over the central U.S. on
Monday, as a trough moves into the Desert Southwest. Between these
two features, moisture and instability will be sufficient for
scattered thunderstorm development from parts of the Desert
Southwest and Intermountain West eastward into the Great Plains.
Instability is forecast to remain relatively weak, and severe
thunderstorms are not forecast across the continental U.S. Monday or
Monday night.

..Broyles.. 09/27/2026

Day 3 Convective Outlook  
NWS Storm Prediction Center Norman OK
0222 AM CDT Sun Sep 27 2026

Valid 291200Z - 301200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
No severe thunderstorms are forecast across the U.S. on Tuesday and
Tuesday night.

...DISCUSSION...
At mid-levels on Tuesday, zonal westerly flow will be in place over
the northwestern U.S. with a trough in the northern Plains. An
upper-level low will move across the Desert Southwest. In the
vicinity of this system, scattered thunderstorms will develop during
the day over much of the Southwest. More isolated storms will be
possible from the central Rockies northeastward into the upper
Mississippi Valley. Instability is expected to remain relatively
weak, and no severe threat is forecast across the continental U.S.
Tuesday and Tuesday night.

..Broyles.. 09/27/2026