ACUS11 KWNS 121525
SWOMCD
MESOSCALE DISCUSSION 0323
NWS STORM PREDICTION CENTER NORMAN OK
1024 AM CDT SAT APR 12 2014
AREAS AFFECTED...PARTS OF SWRN MN...NE IA...SRN WI...NRN IL...SRN
LAKE MI AND ADJACENT NW IND/SWRN MI
CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY
VALID 121524Z - 121730Z
PROBABILITY OF WATCH ISSUANCE...20 PERCENT
SUMMARY...GUSTY WINDS AND HAIL...PERHAPS LOCALLY APPROACHING OR
BRIEFLY EXCEEDING SEVERE LIMITS...MAY CONTINUE ANOTHER COUPLE OF
HOURS WITH SCATTERED STRONGER STORMS ACROSS THE UPPER MIDWEST...SOME
OF WHICH MAY IMPACT THE CHICAGO METRO AREA BY 18-19Z.
DISCUSSION...LOWER/MID TROPOSPHERIC WARM ADVECTION ON THE NOSE OF
WARM ELEVATED MIXED LAYER AIR ADVECTING EAST NORTHEAST OF THE PLAINS
APPEARS TO BE PROVIDING THE PRIMARY SUPPORT FOR THE ONGOING
CONVECTIVE DEVELOPMENT ACROSS THE UPPER MIDWEST. DESPITE SEASONABLY
WEAK TO MODEST MOISTURE WITHIN THE SOUTHERLY FLOW REGIME TO THE EAST
OF THE PLAINS SURFACE TROUGH...LATEST OBSERVATIONAL DATA AND
OBJECTIVE ANALYSIS SUGGEST THAT A LOCAL MAXIMA IN PRECIPITABLE WATER
/UP TO AROUND 1 INCH/ DOES EXIST TO THE EAST OF A SURFACE LOW CENTER
NEAR SIOUX FALLS SD. BENEATH STEEP MID-LEVEL LAPSE RATES THIS
APPEARS TO BE CONTRIBUTING TO THE DESTABILIZATION SUPPORTING THE
STRONG/LOCALLY SEVERE STORMS ON THE WESTERN FLANK OF THE CONVECTIVE
ACTIVITY...WHICH SHOULD CONTINUE TO SPREAD EASTWARD ACROSS
CENTRAL/SOUTHERN WISCONSIN AND NORTHERN ILLINOIS THROUGH EARLY
AFTERNOON.
THE STRONGEST STORMS ALSO APPEAR TO COINCIDE WITH THE MOST
SUBSTANTIVE MODIFICATION OF THE RESIDUAL COOL/STABLE SURFACE BASED
AIR MASS WHICH HAS BEEN ENTRENCHED ACROSS PARTS OF THE UPPER GREAT
LAKES. THIS MAY BE SLOWER TO OCCUR ACROSS CENTRAL WISCONSIN...WHERE
SURFACE TEMPERATURES REMAIN IN THE 40S.
POTENTIAL FOR STRONGEST STORM DEVELOPMENT...NOW THROUGH 18-19Z...
SEEMS TO BE WITH STORMS DEVELOPING ALONG THE SURFACE WARM FRONTAL
ZONE NORTH/EAST OF ROCKFORD IL...TOWARD THE CHICAGO METRO AREA...
WHERE TEMPERATURES ARE RISING THROUGH THE 60S. SURFACE DEW POINTS
REMAIN IN THE LOWER 30S...THOUGH...AND THE INGESTION OF DRIER/MORE
STABLE AIR STILL SEEMS LIKELY TO EVENTUALLY WEAKEN STORM
INTENSITIES.
..KERR/HART.. 04/12/2014
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...GRR...LOT...MKX...DVN...ARX...
LAT...LON 43939241 44169091 43468865 42928751 42638604 41598764
42108930 42509046 43489228 43939241
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