Tuesday, May 31, 2011

MESO: Mesoscale Discussion 1040

ACUS11 KWNS 311800
SWOMCD
SPC MCD 311759
MIZ000-OHZ000-INZ000-ILZ000-WIZ000-MOZ000-312030-

MESOSCALE DISCUSSION 1040
NWS STORM PREDICTION CENTER NORMAN OK
1259 PM CDT TUE MAY 31 2011

AREAS AFFECTED...MID MS VLY INTO IND AND SRN LWR MI

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY

VALID 311759Z - 312030Z

COLD FRONT ASSOCIATED WITH SE MB UPR LOW ATTM EXTENDS FROM FAR ERN
IA SSW INTO CNTRL MO. THE FRONT SHOULD CONTINUE STEADILY E INTO WRN
IL AND ERN MO THROUGH THE AFTN. AHEAD OF THE FRONT...REMNANTS OF
OVERNIGHT MCS IN NEB AND THE DAKOTAS...IN THE FORM OF SHOWERS AND A
FEW TSTMS...ARE NOW OVER N CNTRL AND W CNTRL IL. THIS ACTIVITY HAS
OFFSET SFC HEATING/MAINTAINED SIZABLE SFC-BASED CINH OVER THE NW
HALF OF IL. AT THE SAME TIME...THE ASSOCIATED CLOUDS HAVE SERVED TO
MINIMIZE DEEP MIXING OVER THE REGION...WHILE DEEPER MIXING HAS
OCCURRED E OF THE CLOUDS INTO PARTS OF IND/LWR MI. THIS HAS
RESULTED IN AN AREA OF VEERED LOW LVL FLOW/DECREASED LOW LVL
CONFLUENCE FROM ERN IL INTO NRN IND.

WATER VAPOR IMAGERY ATTM SHOWS A POTENT SHORTWAVE IMPULSE NOW
EXTENDING FROM N CNTRL IA NNW INTO NW MN. THIS FEATURE SHOULD
CONTINUE PIVOTING NE TOWARD THE UPR GRT LKS THROUGH THE REMAINDER OF
THE DAY...WITH WEAK SHORTWAVE RIDGING LIKELY TO OCCUR IN ITS WAKE
FROM CNTRL IL WSWWD INTO MO.

AFOREMENTIONED PRESENCE OF CLOUDS...THE SOMEWHAT WEAKENED/DISRUPTED
LOW LVL CONVERGENCE FIELD...AND THE DEPARTURE OF STRONGER FORCING
FOR ASCENT...CAST SOME UNCERTAINTIES AS TO THE DETAILS OF STORM
DEVELOPMENT/EVOLUTION FROM MO/IL INTO IND/SRN LWR MI LATER TODAY.
NEVERTHELESS...AMPLE MOISTURE AND DEEP SHEAR WILL REMAIN IN PLACE TO
SUPPORT STRONG/SUSTAINED UPDRAFTS ALONG AND AHEAD OF THE COLD FRONT.
IN ADDITION...HEATING...WHILE MUTED ATTM...SHOULD CONTINUE TO
INCREASE AS MCS CLOUDS FURTHER DISSIPATE. GIVEN THIS SETUP...AND
THE POTENTIAL FOR A FEW STORMS TO FORM IN MORE STRONGLY
HEATING/CONFLUENT AREA ALONG LAKE BREEZE BOUNDARY IN SW LWR MI...IT
APPEARS THAT A SVR TSTM WATCH WILL BE NEEDED FOR AT LEAST PARTS OF
THE REGION INCLUDING THE CHICAGO...MILWAUKEE...DETROIT...AND PERHAPS
ST LOUIS METRO AREAS BY MID AFTN.

..CORFIDI.. 05/31/2011

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

ATTN...WFO...DTX...IWX...GRR...IND...LOT...ILX...MKX...LSX...
DVN...

LAT...LON 39248926 39029015 38949121 39649175 41079043 42628922
42968761 42678374 41938383 40278679 39248926

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