Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0800 PM CDT Sun Aug 17 2025

Valid 180100Z - 181200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF
THE CENTRAL/NORTHERN PLAINS AND UPPER MIDWEST...

...SUMMARY...
Scattered thunderstorms over the central and northern Plains may
pose a threat for damaging gusts and hail tonight, while a brief
tornado remains possible over the Midwest this evening.

...Central and northern Plains...
Weak ascent from a broad shortwave trough, visible in evening
water-vapor imagery, is supporting scattered thunderstorm
development across portions of western NE and SD this evening. Some
clustering of initial cells has been noted over the High Plains this
evening. Slight enhancement of southwesterly flow aloft attendant to
the broad shortwave trough suggests some upscale growth is possible
over southern SD and northern/central NE this evening into tonight.
Aided by and increasing southwesterly low-level jet, severe gusts
are possible over parts of NE and southern SD with a loosely
organized cluster/MCS progressing east/southestward.

Farther north along the front in the eastern Dakotas, scattered
storms remain possible tonight, especially as low-level mass
response increases at the nose of the low-level jet. Likely
elevated, sporadic hail and or isolated damaging winds would be
possible with any stronger clusters. Confidence in this scenario is
low owing the weak but persistent subsidence in the wake of the MCV
farther east.

...IA/MN...
Ahead of a diffuse MCV, scattered thunderstorms have developed along
an east-west oriented frontal zone. Along and south of this front,
very moist surface conditions are supporting large buoyancy. Area
VADs and forecast soundings show modest westerly flow aloft,
primarily along the cool side of the boundary. Still, slight
enhancement of low-level shear profiles and vertical vorticity along
the wind shift could support a brief supercell/tornado threat with
occasional stronger updrafts into this evening. With time, the
threat should begin to diminish later tonight as the boundary layer
begins to cool and the MCV continues eastward.

...Northern Rockies/northern High Plains...
Scattered high-based thunderstorms ongoing this evening should
continue into tonight as ascent attendant the shortwave trough over
the Northwest spreads eastward. Moderate southwesterly flow aloft,
and weak buoyancy atop steep low-level lapse rates will remain
supportive of isolated severe gusts with the stronger downdrafts.
The severe risk should steadily progress eastward into southeastern
MT and the far western Dakotas before weakening after sunset
tonight.

...Mid Atlantic...
Lingering scattered thunderstorms may pose a risk for a damaging
wind gust or two for a couple more hours this evening across
portions of the DelMarVa. While general convective trends continue
to suggest a decreasing threat with nocturnal stabilization
underway, a stray gust or two cannot be ruled out before storms off
shore tonight.

..Lyons.. 08/18/2025