SWOMCD
SPC MCD 261842
INZ000-KYZ000-TNZ000-ILZ000-MOZ000-ARZ000-262015-
MESOSCALE DISCUSSION 2033
NWS STORM PREDICTION CENTER NORMAN OK
0142 PM CDT SAT SEP 26 2009
AREAS AFFECTED...PORTIONS ERN MO...CENTRAL/SRN IL...SWRN
INDIANA...WRN KY...NWRN TN.
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE
VALID 261842Z - 262015Z
INCREASING COVERAGE AND ORGANIZATION OF TSTMS IS EXPECTED THROUGH
MID-LATE AFTERNOON...SPREADING/MOVING FROM W-E ACROSS CENTRAL/SRN IL
AND LOWER OH VALLEY REGION WITH MAIN CONCERNS BEING HAIL AND STG-SVR
GUSTS. OCCASIONAL SVR HAIL ALSO MAY OCCUR UNDER IMMEDIATE COLD-CORE
REGION OVER NERN MO AND WRN IL.
MOISTURE CHANNEL IMAGERY INDICATES UPPER COLD-CORE LOW NEAR COU AS
OF 1745Z...FCST TO MOVE EWD TOWARD CENTRAL/SRN IL DURING NEXT
SEVERAL HOURS. ASSOCIATED LARGE SCALE ASCENT/COOLING WILL
CONTRIBUTE TO FAVORABLE DEEP-LAYER LAPSE RATES...ALONG WITH DIABATIC
SFC HEATING. BAND OF TSTMS -- INITIALLY FROM NEAR TAZ SWWD ACROSS
STL AREA TO REYNOLDS COUNTY MO -- MAY STRENGTHEN TO SVR LEVELS AS IT
MOVES EWD INTO DESTABILIZING BOUNDARY LAYER WITH FAVORABLE
DEEP-LAYER SHEAR. SFC WINDS AHEAD OF THIS ACTIVITY APPEAR WEAK AND
CHAOTIC...AMIDST ILL-DEFINED/BROAD LOW PRESSURE AREA COVERING
CENTRAL/SRN PORTIONS OF IL/INDIANA AS WELL AS WRN KY. HODOGRAPH
SIZE THEREFORE MAY BE LIMITED...ALTHOUGH STG MID-UPPER GRADIENT FLOW
CONTRIBUTES TO 45-55 KT EFFECTIVE SHEAR VALUES OVER REGION. THIS
WILL SUPPORT POTENTIAL FOR SUPERCELL DEVELOPMENT WITH ANY RELATIVELY
DISCRETE ACTIVITY...SUCH AS MAY CONTINUE TO DEVELOP IN ZONE OF
LITTLE OR NO CAPPING AHEAD OF MAIN TSTM BAND IN WHICH BOW/LEWP
FEATURES ALSO ARE POSSIBLE. ALTHOUGH NOT AS RICH AS FARTHER SE
ACROSS AL/GA...LOW LEVEL MOISTURE WILL BE ADEQUATE WITH SFC DEW
POINTS LOW 60S OVER S-CENTRAL IL AND S-CENTRAL INDIANA TO SPOTTY 70
F READINGS OVER PORTIONS WRN KY. THIS...ALONG WITH CONTINUED SFC
HEATING...WILL CONTRIBUTE TO MLCAPE NEAR 1000 J/KG. AXIS OF 0-3 KM
CAPE 100-200 J/KG ALREADY IS EVIDENT FROM MEM-SLO WHERE HEATING HAS
BEEN SUSTAINED NEAR SFC THERMAL AXIS...CONTRIBUTING TO WEAKNESS OF
CINH AND POTENTIAL FOR ADDITIONAL DEVELOPMENT...DESPITE LACK OF
CONVERGENCE AHEAD OF CONVECTIVE BOUNDARY.
..EDWARDS.. 09/26/2009
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...LMK...OHX...IND...PAH...LOT...ILX...MEG...LSX...
DVN...SGF...
LAT...LON 37099173 38279056 39029144 39899188 40279163 40828992
40748857 40258772 39068740 37818672 36708726 36348848
36429007 36789109 37099173
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