Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1253 AM CDT Wed May 21 2025
Valid 211200Z - 221200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN THE OZARKS TO
MID-SOUTH AND FAR EASTERN NC...
...SUMMARY...
The most likely corridors for severe storms are across parts of far
eastern North Carolina this afternoon, and the Ozarks into the
Mid-South this evening.
...Eastern NC and southern VA...
Ongoing convection over parts of western NC/VA into the Piedmont is
largely expected to move offshore by 12Z this morning. The surface
cold front that lags well behind this morning activity should
progress towards the South Atlantic Coast into the afternoon.
Secondary cyclogenesis is expected across central to eastern NC,
downstream of a fast mid-level jetlet centered on KY to southern WV
this afternoon. Despite weak mid-level lapse rates, low 70s surface
dew points along the Carolina Coastal Plain will support moderate
buoyancy with a plume of MLCAPE from 1500-2500 J/kg. A couple
supercells may develop ahead of the cyclone, most likely across far
eastern NC and the Outer Banks. A tornado or two, isolated large
hail, and localized strong gusts are the expected hazards.
...Ozarks/Mid-South...
While rich boundary-layer moisture will remain confined across south
TX/LA, a strengthening low-level baroclinic zone is expected during
the afternoon to evening near the KS/OK border east-southeast into
the Mid-South. Guidance is rather consistent in developing at least
elevated convection to the cool side of this zone by evening. This
will be coincident with an intensifying mid-level jetlet merging
into the basal portion of the broad North-Central to Northeast CONUS
trough. Forecast soundings depict potentially very strong mid to
upper-level speed shear within the slightly north of west flow
regime. Coupled with steep mid-level lapse rates, this setup could
yield a few fast-moving elevated supercells. Primary uncertainty is
with the degree of buoyancy given typically overdone MUCAPE in
NAM-influenced guidance. But a focused corridor of large hail
potential seems plausible.
...Upper OH Valley...
A confined corridor of modest boundary-layer heating may occur
downstream of the primary surface cyclone drifting across northern
OH to Lake Erie. Coupled with cooling mid-level temperatures, weak
surface-based buoyancy is expected by midday into the afternoon.
Deep-layer shear will not be strong given proximity to the mid-level
trough, but should be adequate for weak/transient mid-level
rotation. With numerous thunderstorms expected, small to marginally
severe hail and isolated damaging winds are anticipated. A brief
tornado is also possible with storms crossing the warm front before
convection weakens abruptly eastward.
...North FL and south GA...
Along the southeastward-moving cold front, moderate buoyancy is
expected ahead of the front. A veered low-level wind profile will
limit effective bulk shear, but scattered thunderstorms could yield
multicell clustering as updrafts congeal. Isolated damaging winds
and marginally severe hail are anticipated this afternoon.
...Deep South TX...
Very large buoyancy will develop amid strong heating of rather rich
western Gulf moisture. While large-scale signals for ascent are
nebulous, convection will likely develop in northeast Mexico over
the higher terrain this afternoon. Some of this activity may spread
east across the Lower Rio Grande this evening. Weak winds through
the lower half of the buoyancy profile will be a limiting factor to
more organized storms, but any multicell clusters could pose an
isolated severe hail/wind risk.
..Grams/Weinman.. 05/21/2025
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