Mesoscale Discussion 0381
NWS Storm Prediction Center Norman OK
0212 PM CDT Sun Apr 07 2024
Areas affected...parts of southeast Missouri...southern
Illinois...northeast Arkansas and adjacent portions of western
Kentucky/Tennessee
Concerning...Severe potential...Watch possible
Valid 071912Z - 072145Z
Probability of Watch Issuance...40 percent
SUMMARY...Scattered strong thunderstorm activity is expected to
continue to develop through 4-6 PM CDT. This may include the
evolution of a couple widely scattered supercells, posing a risk for
severe hail and potential for a tornado or two.
DISCUSSION...While a weak cold front advancing eastward toward the
mid/lower Mississippi Valley is becoming increasingly diffuse, a
rather sharp low-level moisture gradient is being maintained along a
lingering wind shift now slowly advancing across portions of east
central and southeastern Missouri through central Arkansas. Ahead
of the wind shift, surface dew points are increasing through the
lower/mid 60s in a narrow plume across eastern Arkansas, and the
leading edge of this moisture return may nose across the Missouri
Bootheel into southern Illinois through 21-23Z.
Although ascent associated with weak low-level warm advection within
this regime continues to contribute to considerable cloud cover,
breaks in the overcast are allowing for some insolation beneath the
southeastern periphery of a broad pocket of cool mid-level air which
has overspread much of the northern Great Plains into upper
Mississippi Valley. This is contributing to weak destabilization
and bands of deepening convective development. With further
destabilization through late afternoon (mixed-layer CAPE forecast to
exceed 500 J/kg and perhaps locally approach 1000 J/kg), convective
development appears likely to continue to gradually intensify.
Although wind fields to the southeast of a broad and initially deep,
but filling, surface cyclone centered over northeastern Nebraska are
forecast to undergo notable weakening through early evening,
south-southwesterly to west-southwesterly flow in the 850-500 mb
layer appears likely to remain on the order of 30-60+ kt across the
destabilizing air mass. With increasing low-level inflow of
unstable air, the evolution of widely scattered supercell structures
seems possible by late afternoon. These may eventually become
capable of producing marginally severe hail, and at least some risk
for producing a tornado, before diminishing this evening.
..Kerr/Goss.. 04/07/2024
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...PAH...ILX...MEG...LSX...LZK...
LAT...LON 35209125 37139059 38638966 38708832 37968820 36068891
35328989 35209125