MD 0025 CONCERNING SEVERE POTENTIAL…WATCH UNLIKELY FOR SOUTH-CENTRAL ILLINOIS
Mesoscale Discussion 0025
NWS Storm Prediction Center Norman OK
0206 PM CST Tue Jan 03 2023
Areas affected...South-central Illinois
Concerning...Severe potential...Watch unlikely
Valid 032006Z - 032230Z
Probability of Watch Issuance...20 percent
SUMMARY...Isolated strong to severe thunderstorms are possible
across south-central IL this afternoon. Locally damaging gusts,
isolated large hail, and a tornado or two are possible.
DISCUSSION...Water-vapor imagery and regional VWP data show a
mid-level speed max over MO approaching portions of western IL,
where a north-south oriented baroclinic zone is moving eastward. As
the related large-scale ascent overspreads the front, isolated
thunderstorm development is possible in the vicinity of the front.
Storm development will be aided by continued boundary-layer
moistening/heating and related destabilization in the presence of
large-scale ascent. In fact, a few showers are developing along the
baroclinic zone southeast of St. Louis.
Ahead of the front, lower 60s dewpoints beneath cold temperatures
aloft will contribute to moderate surface-based instability amid
strengthening deep-layer shear characterized by long, generally
straight hodographs (45-50 kts effective bulk shear oriented oblique
to the front). As a result, a couple of loosely organized, splitting
supercell structures are possible in south-central IL this
afternoon. Large hail and a tornado or two are possible with the
initial discrete activity. With time, cell interactions and
localized upscale growth could favor a greater damaging-wind risk
with eastward extent. While clouds have cleared over western IL,
lingering cloud cover over eastern IL casts uncertainty on robust,
sustained storm development. A watch issuance is not expected,
though trends will be monitored.
..Supinie/Weinman/Hart.. 01/03/2023
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...PAH...LOT...ILX...LSX...
LAT...LON 38448815 38058863 37738914 37678954 38009008 38469011
39228999 39688978 40078948 40288913 40498849 40448786
40218770 39728762 39188773 38448815
