[MCD] SWOMCD

[MCD at goshenarc.org]

ACUS11 KWNS 212210
SWOMCD
SPC MCD 212209 
MIZ000-OHZ000-INZ000-ILZ000-212245-

MESOSCALE DISCUSSION 1754
NWS STORM PREDICTION CENTER NORMAN OK
0509 PM CDT WED JUL 21 2004

AREAS AFFECTED...NRN IL/NRN IND/MUCH OF SRN LOWER MI

CONCERNING...SEVERE THUNDERSTORM WATCH 663...

VALID 212209Z - 212245Z

SEVERE STORM OVER DUPAGE/WILL COUNTIES IL MOVING EWD INTO COOK
COUNTY.  IN ADDITION TO LARGE HAIL AND DAMAGING WINDS...NEAR STORM
ENVIRONMENT TORNADO THREAT PARAMETERS HAVE INCREASED SOME OVER THE
LAST TWO HOURS.  DAMAGING WIND THREAT CONTINUES ACROSS SRN LOWER MI.


21Z SURFACE ANALYSIS INDICATED THAT THIS STORM IS LOCATED ALONG AN
E-W SURFACE BOUNDARY WITH THE AIR MASS OVER NERN-ERN IL AND NWRN IND
REMAINS EXTREMELY UNSTABLE /MLCAPE 3500-4500 J/KG/.  THIS STORM IS
LOCATED ALONG A SURFACE BOUNDARY WHERE THE COMBINATION OF EXTREME
INSTABILITY...0-1 KM SRH AROUND 100 M2/S2...AND MLLCL AROUND 900
M...MAY SUPPORT AN ISOLATED TORNADO THREAT.  HOWEVER... WEAK UPPER
LEVEL FLOW WILL TEND TO LIMIT THE THREAT FOR LONG-LIVED TORNADIC
SUPERCELL STRUCTURES.

LINE OF STORMS OVER SW LOWER MI /CURRENTLY EXTENDING FROM MECOSTA TO
ALLEGAN COUNTIES MI/ IS MOVING TO THE ESE AT 30 KT. AIR MASS
DOWNSTREAM IS MODERATELY UNSTABLE AND WILL SUPPORT DAMAGING WIND
THREAT INTO THE EARLY EVENING ACROSS SRN LOWER MI.

..PETERS.. 07/21/2004

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

ATTN...WFO...DTX...APX...IWX...GRR...LOT...ILX...DVN...

41918978 41698797 42658635 43818541 44858243 42538242
39578977 

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