SPC AC 262053
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0353 PM CDT Thu Mar 26 2020
Valid 281200Z - 291200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR MUCH OF
IL/IN...AS WELL AS THE ARK-LA-MISS...
Scattered severe storms will be possible, mainly Saturday afternoon
and evening, across much of the Mississippi and Ohio Valley regions.
A few tornadoes, damaging winds, and large hail will all be
...MS/OH Valley area...
A deepening synoptic cyclone will move from northeast KS Saturday
morning to WI by Saturday night, in advance of an
ejecting/positive-tilt midlevel trough. An elevated mixed layer in
prior days should limit thunderstorm coverage in the warm sector,
and allow low-level moisture to spread northward into IL and the OH
Valley, beneath the remaining steep lapse rate plume through the day
Saturday. Elevated convection will be possible through the day into
the northern half of the OH Valley in a warm advection regime, and
also across IA/WI in the zone of strong ascent preceding the surface
cyclone and midlevel trough. Large hail will be the primary threat
with the elevated storms.
During the day, surface destabilization in advance of the cold front
will contribute to an environment favorable for thunderstorm
development along the front by early afternoon, roughly near the MS
River. Potentially moderate bouyancy (MLCAPE close to 1000 J/kg)
and effective bulk shear in excess of 70 kt will favor supercells,
with broken bands of cells expected given fast storm motions that
will likely exceed the motion of the cold front. Low-level shear
and hodgraph curvature will be largest across the northern part of
the warm sector, where a few tornadoes will be possible, in addition
to damaging winds/large hail. The frontal convection will spread
eastward through the evening/overnight into the OH Valley, with some
potential for isolated severe wind/hail and perhaps tornadoes.
There is some potential for increases in severe probabilities and
some expansion of the northern Slight Risk area in later updates.
Areas of TN/KY will also be monitored for any increase in severe
threat with convection developing northeastward overnight from the
Mid South. The southern Slight Risk area remains unchanged in this
update, though there is uncertainty regarding the magnitude of the
severe threat this far south.
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NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 0730Z