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obwan
09-12-2010, 12:23 PM
Maybe some cold low level thunderstorms develop across the area this evening and tomorrow, with possible winds and hail.


Today 12
...UPPER GREAT LAKES INTO THE MIDWEST...

A LOW-AMPLITUDE SHORT WAVE TROUGH AND ASSOCIATED 50-60 KT MIDLEVEL
JET STREAK NOW OVER THE RED RIVER VALLEY WILL RAPIDLY TRANSLATE
ESEWD THROUGH THE REGION TODAY...ENHANCING A BAND OF DYNAMIC FORCING
FOR ASCENT ALONG SYSTEM TRACK. AT THE SURFACE...LATEST MESOANALYSIS
INDICATES A WEAK COLD FRONT FROM WRN LAKE SUPERIOR SWWD INTO S-CNTRL
MN. BY MID AFTERNOON...THIS BOUNDARY IS EXPECTED TO BECOME ALIGNED
IN MORE OF AN ENE-WSW FASHION FROM THE UPPER PENINSULA OF MI INTO
NRN WI...AND WILL LIKELY SERVE AS THE FOCUS FOR A FEW STRONG TO
MARGINALLY SEVERE STORMS DURING THE LATTER HALF OF THE DIURNAL
HEATING CYCLE.

12Z OBSERVED SOUNDINGS AND SATELLITE-DERIVED PW IMAGERY SHOW THAT
PRE-FRONTAL AIR MASS IS RELATIVELY DRY WITH BOUNDARY LAYER DEW
POINTS IN THE 50S AND PW VALUES WELL BELOW AN INCH. HOWEVER...
UPSTREAM OBSERVATIONS SUGGEST THAT NOTABLE MID-TROPOSPHERIC COOLING
WILL SPREAD SEWD THROUGH THE REGION TODAY IN CONJUNCTION WITH
ABOVE-MENTIONED SHORT WAVE TROUGH. WHEN COUPLED WITH DAYTIME
HEATING AND SUBSEQUENT STEEPENING OF LOW-LEVEL LAPSE
RATES...PRE-FRONTAL AIR MASS IS EXPECTED TO BECOME MARGINALLY
UNSTABLE WITH MLCAPE APPROACHING 500 J/KG. GIVEN THE PRESENCE OF
40-50 KT OF DEEP WNWLY SHEAR...SETUP WILL FAVOR THE DEVELOPMENT OF
SOME STORM ORGANIZATION WITH A RISK FOR LOCALLY DAMAGING WIND GUSTS
AND MARGINALLY SEVERE HAIL THROUGH THIS EVENING.


tomorrow 13
...NORTHEAST STATES/WESTERN NEW ENGLAND...
IT APPEARS THAT RELATIVELY LOW-TOPPED STORMS MAY DEVELOP ALONG/AHEAD
OF AN ADVANCING COLD FRONT MONDAY AFTERNOON. GIVEN THE POTENTIAL FOR
MODEST DAYTIME DESTABILIZATION AND THE DEVELOPMENT OF STEEP LOW TO
MID LEVEL LAPSE RATES...IN CONJUNCTION WITH MODERATELY STRONG/NEARLY
UNIDIRECTIONAL FLOW WEST-NORTHWESTERLY FLOW...IT APPEARS THAT THE
STRONGEST STORMS WILL BE CAPABLE OF GUSTY WINDS AND HAIL MONDAY
AFTERNOON.