AREAS AFFECTED...LOWER MI...SE WI...NE IL AND SRN LAKE MI
CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY
VALID 310539Z - 310715Z
PROBABILITY OF WATCH ISSUANCE...20 PERCENT
SUMMARY...AN ISOLATED SEVERE THREAT MAY CONTINUE FOR A FEW MORE
HOURS ACROSS LOWER MI EXTENDING WWD INTO SE WI AND NE IL. WIND
DAMAGE AND HAIL WILL BE THE PRIMARY THREATS. THE SEVERE THREAT IS
EXPECTED TO BE TOO MARGINAL TO WARRANT WW ISSUANCE.
DISCUSSION...A NEARLY CONTINUOUS LINE OF STORMS EXTENDS FROM CNTRL
LOWER MI WWD INTO NE IL JUST AHEAD OF A SHORTWAVE TROUGH EVIDENT ON
WATER VAPOR IMAGERY. LARGE-SCALE ASCENT ASSOCIATED WITH THE
SHORTWAVE TROUGH IS PROVIDING SUPPORT FOR THE LINE IN SPITE OF A
CAPPING INVERSION THAT IS LIKELY MAKING THE CONVECTION ELEVATED. THE
LINE IS LOCATED ON THE ERN EDGE OF MODERATE INSTABILITY WHERE MLCAPE
VALUES VARY FROM LESS THAN 500 J/KG IN CNTRL LOWER MI TO AROUND 1500
J/KG IN SERN WI. IN ADDITION TO THE INSTABILITY...WSR-88D VWPS IN
THE VICINITY OF THE LINE SHOW 30 TO 40 KT OF DEEP LAYER SHEAR. THIS
COMBINED WITH MID-LEVEL LAPSE RATES AROUND 7.5 C/KM SHOULD BE
SUFFICIENT FOR A SEVERE THREAT DURING THE OVERNIGHT PERIOD. THE LINE
IS MOVING SSEWD AT AROUND 30 KT AND APPEARS TO HAVE A SOMEWHAT
ORGANIZED COLD POOL. FOR THIS REASON...A WIND DAMAGE THREAT SHOULD
PERSIST FOR A FEW MORE HOURS. DUE TO THE STEEP MID-LEVEL LAPSE
RATES...HAIL MAY ALSO OCCUR WITH THE STRONGER CORES EMBEDDED IN THE
LINE.
..BROYLES/THOMPSON.. 07/31/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...DTX...APX...IWX...GRR...LOT...MKX...
LAT...LON 43928389 43448562 43238738 43158882 42488890 42108848
41998736 42388483 42968347 43928389
