MESO: Mesoscale Discussion 0907

ACUS11 KWNS 011831
SWOMCD
SPC MCD 011831
INZ000-ILZ000-IAZ000-011930-

MESOSCALE DISCUSSION 0907
NWS STORM PREDICTION CENTER NORMAN OK
0131 PM CDT MON JUN 01 2009

AREAS AFFECTED...PARTS OF FAR ERN IA / NRN IL / NWRN AND N-CNTRL IND

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY

VALID 011831Z - 011930Z

THE SEVERE THREAT WILL GRADUALLY INCREASE THIS AFTERNOON ACROSS
PORTIONS OF FAR ERN IA/NRN IL EXTENDING EWD INTO NWRN AND N-CNTRL
IND TOWARDS LATE AFTERNOON/EARLY EVENING. THE PRIMARY THREAT WITH
THE ACTIVITY WILL BE LARGE HAIL/DMGG WINDS.

VISIBLE IMAGERY SHOWS A MID-LEVEL VORTICITY MAXIMUM MOVING ESEWD
OVER CNTRL IA AS OF 1830Z. RECENT SURFACE ANALYSIS SHOWS A SAGGING
SEWD MOVING COLD FRONT OVER PARTS OF SERN WI DRAPED WSWWD INTO
E-CNTRL IA. OUTFLOW BOUNDARY ORIGINATING FROM LAST NIGHTS MCS NOW
OVER SERN OH/WRN WV HAS BEEN REINFORCED AS STRONG INSOLATION TO THE
S OF THE BOUNDARY IS CONTRIBUTING TO A SUBSTANTIAL DIFFERENTIAL
HEATING ZONE/MODEST LOW LEVEL CONVERGENCE TRAILING NWWD INTO NWRN
IND/NRN IL.

AS TEMPS CONTINUE TO WARM INTO THE 80S F AMIDST A HIGHER QUALITY
MOIST AIRMASS /PRECIPITABLE WATER 1.4 INCH/ RESIDING OVER NRN
IL/NWRN IND...AN AREA OF MODERATE POTENTIAL INSTABILITY
/CHARACTERIZED BY MLCAPE 2000-3000 J/KG/ HAS DEVELOPED ALONG AND S
OF THE BOUNDARY. SOMEWHAT FOCUSED AREA OF ASCENT ALONG INTERSECTION
OF COLD FRONT/DIFFERENTIAL HEATING BOUNDARY AHEAD OF APPROACHING
VORTICITY MAXIMUM SHOULD PROVE ENOUGH TO WEAKEN THE CAP WITH
ADDITIONAL TSTM DEVELOPMENT. ALTHOUGH SURFACE WINDS HAVE VEERED TO
WLY...A WLY 50+ KT MID-LEVEL SPEED MAX /SAMPLED BY WLC/LOT VWP DATA/
SHOULD AID IN ORGANIZING STORMS INTO CLUSTERS/SMALL BOWING SEGMENTS
WITH TIME. AS STORMS MATURE AND ORGANIZE...THEY WILL LIKELY POSE A
LARGE HAIL/DMGG WIND THREAT EVOLVING INTO MORE OF A WIND THREAT AS
STORMS MOVE GENERALLY ESEWD ALONG INSTABILITY GRADIENT.

..SMITH.. 06/01/2009

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

ATTN...WFO...IWX...IND...LOT...ILX...DVN...

LAT...LON 40668840 41088970 41319079 41499111 41649110 41849094
41919079 42078995 42118957 42018851 41838704 41678669
41408639 40978631 40618650 40328681 40308754 40668840

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