ACUS01 KWNS 191629

SWODY1

SPC AC 191628



Day 1 Convective Outlook  

NWS Storm Prediction Center Norman OK

1128 AM CDT Tue Aug 19 2025



Valid 191630Z - 201200Z



...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF

THE OHIO VALLEY TO THE SOUTHERN/CENTRAL PLAINS...AND OVER PORTIONS

OF WESTERN/NORTHERN MONTANA...



...SUMMARY...

Scattered thunderstorms capable of producing occasional damaging

winds will be possible across parts of the south-central Plains and

Ozarks to the Ohio Valley this afternoon and evening. Isolated

severe thunderstorms may also occur this evening across parts of

western and northern Montana.



...Ohio Valley to the Central/Southern Plains...

Upper ridging will remain prominent today across the Southwest and

southern/central Rockies, as a weak mid/upper-level trough moves

east-southeastward across the Great Lakes and OH Valley regions. At

the surface, a weak cold front is forecast to advance

east-southeastward across parts of the OH Valley and mid MS Valley

today, and more slowly southward over portions of the

central/southern Plains while weakening. This boundary should aid in

at least scattered thunderstorm development through the afternoon as

diurnal heating of a moist airmass along/south of the front occurs.

While deep-layer flow and related shear are expected to remain

generally weak, moderate to strong instability and the steepening of

low-level lapse rates may support occasional strong to damaging

winds with water-loaded downdrafts within the stronger cores. Only

minor adjustments have been made to the broad Marginal Risk based on

latest observational and short-term guidance trends.



...Northern Rockies/High Plains...

An embedded mid-level shortwave trough will advance northeastward

this evening and overnight across parts of the northern Rockies and

adjacent High Plains on the western to northern periphery of

prominent upper ridging over the Southwest. Isolated to perhaps

widely scattered thunderstorms should develop through the evening

hours across parts of western MT and vicinity as large-scale ascent

associated with the shortwave trough overspreads the northern

Rockies. Instability is forecast to remain rather limited, but

steepened lapse rates aloft and a well-mixed boundary layer could

still aid in some convective downdraft enhancement, with isolated

strong to severe gusts possible as convection spreads northeastward

towards the international border.



...Coastal Texas...

A weak mid-level perturbation with ongoing thunderstorms along parts

of the middle TX Coast should continue south-southwestward this

afternoon and evening. Low/mid-level flow should remain modest,

which will generally limit thunderstorm organization. Still, some

clustering could support isolated strong/gusty winds in the presence

of increasing instability this afternoon across parts of

south-central TX and the lower TX Coast. Confidence in

severe-caliber gusts remains too low to include any severe

probabilities at this time.



..Gleason/Wendt.. 08/19/2025



$$