MESO: Mesoscale Discussion 0851

ACUS11 KWNS 201833
SWOMCD
SPC MCD 201833
KYZ000-ILZ000-TNZ000-MOZ000-ARZ000-202000-

MESOSCALE DISCUSSION 0851
NWS STORM PREDICTION CENTER NORMAN OK
0133 PM CDT SUN MAY 20 2012

AREAS AFFECTED...SRN IL...WRN KY/TN...NERN AR...SERN MO

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 201833Z - 202000Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...MULTICELL CLUSTERS ARE FORECAST TO DEVELOP ACROSS NERN
AR...SERN MO...SRN IL AND WRN KY/TN DURING THE AFTERNOON. ISOLATED
DAMAGING WIND GUSTS AND LARGE HAIL WILL BE POSSIBLE. WW DOES NOT
APPEAR NECESSARY ATTM...BUT TRENDS WILL BE MONITORED FOR GREATER
THAN ANTICIPATED STORM ORGANIZATION.

DISCUSSION...AT 18Z...MESOANALYSIS SHOWED A COLD FRONT EXTENDING
SWWD OUT OF SRN WI INTO CNTRL MO AND ERN OK. SURFACE AIRMASS AHEAD
OF THE FRONT IS CHARACTERIZED BY TEMPERATURES IN THE 80S TO LOW
90S...WITH DEWPOINTS GENERALLY IN THE UPR 50S TO LOW 60S. THE STRONG
HEATING IS AIDING IN THE DEVELOPMENT OF STEEP LOW-LEVEL LAPSE RATES
AND MLCAPE VALUES FROM 1500-2000 J/KG. IN ADDITION...LATEST WV
IMAGERY SHOWS A CONVECTIVELY ENHANCED VORT LOBE ENTERING SWRN MO AND
NWRN AR. ASCENT ASSOCIATED WITH THIS FEATURE COMBINED WITH STRONG
DESTABILIZATION WILL LIKELY FAVOR AN INCREASE IN THUNDERSTORM
COVERAGE OVER SRN MO/NRN AR DURING THE NEXT FEW HRS...WITH SIMILAR
TREND OCCURRING FARTHER E OVER SRN IL AND WRN KY/TN SOON AFTER.
THOUGH DEEP-LAYER SHEAR IS RELATIVELY WEAK /EFFECTIVE BULK WIND
DIFFERENCE AOB 20 KT/...THE PROGRESSIVE NATURE OF THE VORT LOBE
RESIDING WITHIN BASE OF NRN STREAM TROUGH MAY ENHANCE EWD MOTION OF
STORMS AND INCREASE THE POTENTIAL FOR AN ORGANIZED SVR WEATHER
THREAT. TRENDS WILL CONTINUE TO BE MONITORED FOR THIS SCENARIO.

..GARNER/WEISS.. 05/20/2012

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...PAH...ILX...MEG...LSX...LZK...SGF...

LAT...LON 35149187 36519226 37829206 39239051 38758867 37588801
36378818 35048978 35149187

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