Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1239 AM CDT Fri Sep 05 2025
Valid 051200Z - 061200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE BORDER
AREAS OF TN/MS/AL TO WV/OH...
...SUMMARY...
Scattered damaging winds, isolated severe hail, and a brief tornado
or two are possible from the Upper Ohio to Tennessee Valleys during
the late afternoon and evening.
...Upper OH to TN Valleys...
Neutral mid-level height change and initially weak convergence along
a slow-moving cold front should delay diurnal convective
development. But eastward progression of a low-amplitude impulse,
currently over western KS, and strengthening low-level convergence
should yield scattered thunderstorms in the late afternoon to early
evening. The bulk of strong mid-level flow will largely lag behind
the portion of the front that is south of the Upper OH Valley. But
with the late day timing of storms, an extensive plume of moderate
buoyancy should be prevalent ahead of it. Several multicell clusters
and transient supercell structures should develop during the evening
within the moderately sheared, southwesterly flow regime. Scattered
damaging winds will be the primary hazard, with isolated severe hail
and a brief tornado also possible. The severe threat will diminish
towards late evening given the extensive overturning and lack of
stronger low-level flow/shear to sustain the threat overnight.
...North TX to Mid-South...
An elongated mid-level thermal trough, characterized by 500-mb
temperatures of -10 to -12 C, will extend into north TX, well to the
south of a persistent vertically stacked cyclone over northern ON.
Most guidance suggests low to mid-level wind fields will be modest
and contain veer-back-veer signatures. Strong speed shear should be
mainly confined above 500 mb, coincident with poor upper-level lapse
rates atop steeper mid-level lapse rates. Consensus of CAM guidance
suggests a messy convective mode should be common as convection
increases in the late afternoon and evening, along the more
west/east-oriented portion of the surface cold front. Given these
factors, have maintained a level 1-MRGL risk for an isolated severe
hail/wind threat with a southward shift based on latest guidance.
..Grams/Squitieri.. 09/05/2025
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