Day 3 Convective Outlook  
NWS Storm Prediction Center Norman OK
0231 AM CDT Fri Aug 21 2026

Valid 231200Z - 241200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS SOUTHWEST
TO CENTRAL MONTANA AND ACROSS PARTS OF THE NORTHEAST...

...SUMMARY...
Strong to severe thunderstorms capable of large hail and wind gusts
are possible in portions of the Northeast and across parts of
southwest and central Montana.

...Southwest into central Montana...
A mid-level shortwave trough will move across the Pacific Northwest
and into eastern British Columbia. While the parent trough is
forecast to deamplify through the period, moderate mid-level flow is
forecast to remain across much of Montana. Weak to potentially
moderate instability is forecast to develop across southwest into
central Montana. The moderate mid-level flow should provide ample
shear for storm organization including some supercell potential.
Strong heating will support steep low-level lapse rates and some
severe wind gust threat with the strongest storms.

...Portions of the Northeast...
A mid-level trough will become negatively tilted as it pivots from
the Great Lakes to the Northeast on Sunday. A broad 1006-1010mb
surface low is forecast somewhere in the vicinity of western New
York, southeast Ontario and southern Quebec. Storms are forecast by
mid-day along a cold front that should extend from New York into
central Pennsylvania on Sunday morning and move eastward through the
day. The environment ahead of this front is forecast to have
moderate to strong shear and relatively weak instability. Forecast
soundings show a lower storm top environment due to warmer
temperatures aloft. However, despite the weak instability, the
expectation for at least some supercell threat, combined with decent
instability within the hail growth zone and strong shear may support
some large hail and damaging wind gusts Sunday afternoon/evening.

..Bentley.. 08/21/2026