MESO: Mesoscale Discussion 2034

ACUS11 KWNS 262223
SWOMCD
SPC MCD 262223
KYZ000-INZ000-TNZ000-ILZ000-MOZ000-270000-

MESOSCALE DISCUSSION 2034
NWS STORM PREDICTION CENTER NORMAN OK
0523 PM CDT SAT SEP 26 2009

AREAS AFFECTED...SRN IL...WRN KY AND SRN IND

CONCERNING...SEVERE THUNDERSTORM WATCH 744...

VALID 262223Z - 270000Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 744
CONTINUES.

THREAT FOR ISOLATED DAMAGING WIND AND LARGE HAIL WILL PERSIST
THROUGH THE EARLY EVENING OVER EXTREME SRN IL...SRN IND AND WRN KY.
SOME THREAT FOR SEVERE WEATHER EXISTS WITH STORMS DEVELOPING EAST OF
WW 744 ACROSS W CNTRL KY AND SRN IND...BUT THREAT IN THESE AREAS
WILL PROBABLY REMAIN TOO LIMITED IN DURATION FOR ANOTHER WW
ISSUANCE.

EARLY THIS EVENING A LINE OF THUNDERSTORMS WITH OCCASIONAL EMBEDDED
ROTATING UPDRAFTS EXTENDS FROM SWRN IND SWWD TO NEAR THE KY-IL
BORDER MOVING ESE AT AROUND 30 KT. OVERALL TREND HAS BEEN FOR STORMS
TO UNDERGO A DECREASE IN INTENSITY. SRN PORTION OF THE LINE APPEARS
TO HAVE BECOME OUTFLOW DOMINANT WITH AN EXTENSIVE OUTFLOW BOUNDARY
EVIDENT ON RADAR JUST AHEAD OF THE STRONGER CORES. THE LINE IS
CURRENTLY MOVING THROUGH THE AXIS OF GREATEST SURFACE BASED
INSTABILITY WITH 500-1000 J/KG MLCAPE AND MAY REMAIN CAPABLE OF
PRODUCING ISOLATED LARGE HAIL AND STRONG WIND GUSTS NEXT COUPLE
HOURS.

OTHER MORE WIDELY SCATTERED DISCRETE STORMS HAVE DEVELOPED FARTHER
EAST IN WARM SECTOR ACROSS W CNTRL KY WHERE DIABATIC HEATING HAS
BEEN SUFFICIENT TO DESTABILIZE THE BOUNDARY LAYER. THIS ACTIVITY IS
DEVELOPING WITHIN AN ENVIRONMENT WITH WEAK MID LEVEL LAPSE RATES BUT
WITHIN BAND OF STRONG BULK SHEAR ATTENDING MID LEVEL JET ROTATING
THROUGH BASE OF UPPER TROUGH. SOME OF THESE STORMS APPEAR TO BE
INTERACTING WITH A COUPLE OF E-W ORIENTED SURFACE BOUNDARIES AND VWP
DATA SHOW VEERING WITHIN THE LOWEST 2 KM. HOWEVER...WEAK FLOW IS
LIMITING THE SIZE OF LOW LEVEL HODOGRAPHS. MARGINALLY SEVERE
HAIL...GUSTY WINDS AND AN ISOLATED BRIEF TORNADO WILL BE POSSIBLE
NEXT HOUR OR TWO WITH THESE STORMS...BUT TREND SHOULD BE FOR
ACTIVITY TO BEGIN A GRADUAL DECREASE IN INTENSITY WITH THE ONSET OF
NOCTURNAL COOLING.

..DIAL.. 09/26/2009

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

ATTN...WFO...LMK...OHX...PAH...

LAT...LON 36808962 37958751 38648645 38018590 36718633 36648874
36808962

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