138
ACUS11 KWNS 301941
SWOMCD
SPC MCD 301940
ILZ000-MOZ000-302145-
MESOSCALE DISCUSSION 0621
NWS STORM PREDICTION CENTER NORMAN OK
0240 PM CDT WED APR 30 2025
AREAS AFFECTED...EAST-CENTRAL MISSOURI INTO SOUTHERN ILLINOIS
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE
VALID 301940Z - 302145Z
PROBABILITY OF WATCH ISSUANCE...40 PERCENT
SUMMARY...A FEW STORMS ARE POSSIBLE ALONG AN OUTFLOW BOUNDARY. ALL
SEVERE HAZARDS WOULD BE POSSIBLE. A WATCH IS UNCERTAIN IN THE SHORT
TERM, BUT ISSUANCE IS POSSIBLE THIS AFTERNOON DEPENDING ON
OBSERVATIONAL TRENDS.
DISCUSSION...AIRMASS MODIFICATION AFTER EARLIER CONVECTION HAS BEEN
EVIDENT OVER THE PAST COUPLE OF HOURS IN CENTRAL MISSOURI AND
SOUTHERN ILLINOIS. THE PRIMARY OUTFLOW BOUNDARY IS SITUATED JUST
SOUTH OF ST. LOUIS AND EXTENDS INTO FAR SOUTHERN ILLINOIS AND
SOUTHERN INDIANA. DEWPOINTS SOUTH OF THE BOUNDARY HAVE INCREASED TO
UPPER 60S F EXCEPT FOR PARTS OF SOUTHEASTERN MISSOURI WHICH HAS ONLY
RECOVERED INTO THE LOW 60S F. NORTH OF THE OUTFLOW BOUNDARY, STABLE
BILLOW CLOUDS REMAIN. HOWEVER, VERY NEAR THE BOUNDARY TEMPERATURES
AND DEWPOINTS HAVE INCREASED AND AT LEAST SOME MLCIN HAS BEEN
REMOVED AND CONVECTION HAS BEGUN TO SLOWLY DEEPEN.
WITH 40 KTS OF EFFECTIVE SHEAR (MORE FAVORABLY ORIENTED ACROSS THE
BOUNDARY ON ITS WESTERN HALF), SUPERCELLS WOULD BE EXPECTED IF
STORMS DEVELOP. LARGE HAIL AND DAMAGING WINDS WOULD BE POSSIBLE. A
TORNADO OR TWO WOULD ALSO BE POSSIBLE FOR STORMS INTERACTING WITH
THE MORE BACKED EASTERLY/SOUTHEASTERLY WINDS ON THE COOLER SIDE OF
THE BOUNDARY. BEING IN THE WAKE OF AN EARLIER MCV, FORCING FOR
ASCENT WILL BE NEBULOUS AND WILL DEPEND ON HEATING/DESTABILIZATION
ALONG THE OUTFLOW. TRENDS WILL CONTINUE TO BE MONITORED. A WATCH IS
POSSIBLE THIS AFTERNOON.
..WENDT/HART.. 04/30/2025
..PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...PAH...ILX...LSX...
LAT...LON 38359140 38649151 39179104 39229055 38878972 38828868
38808815 38618795 38168806 37928814 37538862 37558986
38359140
MOST PROBABLE PEAK TORNADO INTENSITY...85-115 MPH
MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN
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