Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0758 PM CDT Wed Aug 12 2026
Valid 130100Z - 131200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL PLAINS INTO WESTERN IOWA...
...SUMMARY...
Multiple supercells with large hail potential across the
northern/central High Plains should evolve into a bowing cluster
tonight while spreading eastward across Nebraska and eventually into
Iowa by early Thursday morning. This cluster will be capable of
producing scattered severe/damaging winds.
...Northern/Central Plains into Iowa...
A mix of clusters and supercells is ongoing this evening from far
northeast CO into western NE. The environment downstream into
central/eastern NE remains favorable to maintain severe convection
along/near a surface front. Large hail will remain possible with any
sustained supercells given 35-45+ kt of deep-layer shear, and
eventual upscale growth into a bowing cluster appears probable
tonight with modestly enhanced east-southeasterly low-level flow
providing an influx of warm/moist air. If this occurs, then the
threat for severe/damaging winds would increase across
central/eastern NE and perhaps eventually western IA, with isolated
gusts of 75+ mph possible. Severe probabilities have been adjusted
based on latest observational and short-term guidance trends.
Reference Mesoscale Discussion 1961 for more details regarding the
near-term severe threat across northeast CO/western NE.
...Mid Mississippi Valley into the Lower Ohio Valley...
Ongoing thunderstorm clusters across parts of the mid MS and lower
OH Valleys have mostly diminished in intensity as they have become
generally displaced south of the stronger mid-level flow across the
Midwest/Great Lakes. Even with the gradual weakening trend observed,
a couple of stronger clusters persist. Isolated damaging winds will
remain possible for a couple more hours this evening as this
activity spreads slowly southward.
...Northeast...
Loosely organized cells may continue to pose an isolated hail/gusty
wind threat for the next hour or two across southern NY and vicinity
along/near a surface front. The loss of daytime heating and gradual
decrease in instability should result in eventual weakening of
ongoing convection.
...Lower Colorado River Valley...
High-based thunderstorms which developed this afternoon in a hot and
well-mixed boundary layer across interior southern CA and western AZ
may remain capable of producing occasional severe gusts for a couple
more hours this evening.
..Gleason.. 08/13/2026
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