Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0800 PM CDT Wed Sep 17 2025

Valid 180100Z - 181200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE
SOUTH-CENTRAL HIGH PLAINS...

...SUMMARY...
Isolated severe thunderstorms remain possible across parts of the
south-central High Plains, with hail and localized severe gust
potential.

...South-central High Plains...
Scattered strong to severe cells with hail potential currently
extend from the Colorado Springs area southeastward into the
northwest TX Panhandle. Cool midlevel temperatures as well as
easterly low-level winds veering to westerly aloft are supporting
the cellular storm mode with longevity.

Height falls with the weak upper trough will continue overnight, and
southerly winds around 850 mb may support weak theta-e advection for
a few hours this evening. Given substantial instability noted on the
00Z DDC sounding, an isolated hail threat may eventually develop
from the west.

Elsewhere, a cluster of storms persists over south-central KS near
the OK border, and near a warm front. Isolated hail or wind may
persist in this area as well, and perhaps affect the rest of
south-central KS later this evening with marginal hail.

..Jewell.. 09/18/2025

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1159 PM CDT Wed Sep 17 2025

Valid 181200Z - 191200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS CENTERED FROM
OKLAHOMA INTO MISSOURI...AND INCLUDING PORTIONS OF SURROUNDING
STATES...

...SUMMARY...
Strong to locally severe storms are possible from late afternoon
into tonight from parts of Oklahoma into Missouri and over small
parts of adjacent states.

...Discussion...
An upper trough will remain over much of the central and northern
Plains, with cool midlevel temperatures extending as far south as
northern TX. An upper disturbance will move across OK and KS during
the day, pivoting into IA/MO/AR during the evening. Cooling
aloft/height falls associated with this feature should aid daytime
destabilization.

At the surface, a weak boundary should extend from the TX Panhandle
into northern OK, and into the eastern KS/western MO vicinity.
Daytime heating will combine with the cool air aloft and a
marginally moist boundary layer to produce MLCAPE on the order of
1500 J/kg. Early day rain/storms may occur over KS beneath midlevel
cold pocket, and some of this activity could eventually produce
small hail. 

By late afternoon and as the low-level lapse rate plume is
established, renewed development is expected from eastern KS into
OK, with activity pushing into western MO and northwest AR through
evening. Overall, deep layer shear will be marginal, however, strong
high-level flow may support a greater chance of hail from the TX
Panhandle into OK, while the coldest midlevel temperatures also
support hail from eastern KS into MO.

..Jewell.. 09/18/2025

Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1223 AM CDT Thu Sep 18 2025

Valid 191200Z - 201200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Organized severe storms are not currently expected on Friday.

...Synopsis...

An upper shortwave trough will move across the northern/central
Plains to the Mid/Upper MS Valley on Friday. At the surface, a weak
low over southwest MN will lift north through the period, while a
broad area of weak low pressure overspreads the central High Plains.
Light southerly low-level flow will maintain mid 50s to mid 60s F
dewpoints from the south-central U.S. northward into the Upper MS
Valley. Pockets of weak instability are forecast, supporting diurnal
thunderstorm activity from the southern Plains into the Mid/Upper MS
Valley. Poor lapse rates and generally weak vertical shear will
preclude severe thunderstorm potential through evening. 

As the upper shortwave trough ejects across NE toward the MO Valley
overnight, isolated elevated convection could develop over KS in a
warm advection regime. Cooling aloft will support steepening
midlevel lapse rates. Northwesterly flow aloft will also strengthen
on the back side of the upper trough. A couple of strong storms
could produce sub-severe hail.

Additional thunderstorms are possible across parts of the West as an
upper shortwave trough moves northward across CA/NV into OR, an
shortwave perturbations migrate through upper ridging over the Four
Corners.

..Leitman.. 09/18/2025