SPC MD 498

SPC MD 498


Mesoscale Discussion 0498
NWS Storm Prediction Center Norman OK
0114 PM CDT Sat Apr 20 2024

Areas affected…Southern Mississippi to southwest Georgia

Concerning…Severe potential…Watch unlikely

Valid 201814Z – 202015Z

Probability of Watch Issuance…5 percent

SUMMARY…Thunderstorms developing within the next 1-2 hours will
pose a severe hail/wind threat through the late afternoon and
evening hours. Watch issuance is not expected given the isolated
nature of the threat and marginal nature of the convective

DISCUSSION…Several convective towers are noted in GOES day cloud
phase RGB imagery along a cool front/surface trough draped from
central GA to southern AL/MS. A few of the deeper convective towers
across southwest GA and southeast AL (where inhibition is quickly
eroding as surface temperatures climb into the 80s) have begun to
produce lightning flashes, suggesting that more robust convective
initiation is either underway or imminent. In general, these cells
are developing within a marginal thermodynamic and kinematic
environment characterized by 6-7 C/km mid-level lapse rates, MLCAPE
on the order of 1000 J/kg, weak low-level winds, and effective bulk
shear values between 25-30 knots (based on regional VWP observations
and latest mesoanalyses). However, this parameter space is
sufficient for a low-end severe hail (hail stones up to 1.25 inch
appear possible) and wind threat – especially across southeast AL
into southwest GA where low-level lapse rates are approaching 7-8
C/km and may support stronger outflow winds. Initially isolated
cells will undergo gradual upscale growth through the late
afternoon/evening as they propagate east/southeast along the
boundary. However, the overall severe threat is expected to remain
sufficiently localized to preclude watch issuance.

..Moore/Goss.. 04/20/2024

…Please see www.spc.noaa.gov for graphic product…


LAT…LON 31419056 31598816 32158650 32548541 32658448 32608395
32248370 31818372 31508389 31038449 30768540 30738625
30778784 30648865 30548966 30509023 30699061 30899091
31099094 31339091 31419056

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