Sneaky setup tomorrow
THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
THE SOUTHERN PLAINS...
...SUMMARY...
Severe storms are possible across parts of the southern Plains
tomorrow/Thursday, with large hail the main threat. A few instances
of 2+ inch diameter hail are possible.
...Synopsis...
Broad northwesterly flow will prevail across much of the eastern
U.S. as a mid-level trough ejects into the Atlantic, an upper ridge
builds over the central CONUS, and a pronounced mid-level impulse
traverses the northern Rockies tomorrow (Thursday). A surface low
will track along the Mid-Atlantic Coastline while surface high
pressure overspreads much of the Midwest into the Southeast, and lee
troughing prevails across the southern Plains. Thunderstorms are
likely along the East Coast and the FL Peninsula, in association
with the departing upper trough. Storms developing ahead of a
southward-sagging cold front in FL have the best potential for
becoming strong to locally severe over the East Coast. At least
scattered thunderstorms are also likely across the Southern Plains,
northwestward into the northern Rockies, given lee troughing and
low-level upslope flow. Thunderstorms developing along a baroclinic
zone along the Red River will benefit from strong instability and
adequate wind shear, and will have the potential to become severe.
...Southern Plains...
Elevated thunderstorms are expected to develop in central OK within
a warm-air advection regime, to the north of a west-to-east oriented
baroclinic boundary, which is expected to be situated along the Red
River during the morning/early afternoon hours. Through the day,
storms are expected to propagate southward toward a surface-based
airmass over northern TX, where upper 60s/low 70s F surface
dewpoints beneath 8 C/km mid-level lapse rates will contribute to
2500-4000 J/kg MLCAPE. Low-level southerly flow, quickly veering to
northwesterly and strengthening with height, will result in
elongated hodographs with some low-level curvature near the
baroclinic boundary. As such, the overall CAPE/shear parameter space
will support supercells with large to very large hail potential. If
a supercell can anchor along the baroclinic boundary, a tornado will
also be possible.
...East Florida Peninsula...
A southward-sagging cold front will begin to stall across the FL
Peninsula during the afternoon hours, preceded by rich low-level
moisture beneath 6.5-7.5 C/km mid-level lapse rates, which will
boost MLCAPE over 2500 J/kg. Modest northwesterly mid-level flow
impinging on the peninsula will encourage deep-layer speed shear
over 40 kts, that in tandem with moderate to strong instability,
will support multicells and transient supercells by afternoon. Large
hail and strong, damaging wind gusts are the primary threats with
the most intense storms.
...Northern Rockies...
Scattered thunderstorm development is expected across central and
northern ID into southwestern MT as strong forcing for ascent with
the passing mid-level trough overspreads a deep, mixed boundary
layer during the afternoon. Forecast soundings show inverted-v
profiles extending up to 500 mb. As such, some downward momentum
transport via evaporative cooling should encourage stronger wind
gusts with the deeper storm cores. However, confidence is not high
enough for severe gusts to introduce Category 1/Marginal risk
probabilities at this time.
