SPC AC 110539
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1239 AM CDT WED JUN 11 2008
VALID 121200Z - 131200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE WESTERN GREAT LAKES
SWWD INTO PORTIONS OF KS/OK...
...SYNOPSIS...
UNSEASONABLY COLD AND DEEP UPPER LOW IS FORECAST TO MOVE SLOWLY EWD
ALONG THE U.S./CANADIAN BORDER FROM FAR NWRN ND INTO EXTREME SERN
MANITOBA...WITH AN ASSOCIATED BROAD UPPER TROUGH EXTENDING FROM THE
NRN/CENTRAL ROCKIES EWD INTO THE MID/UPPER MS VALLEY. A COLD FRONT
ASSOCIATED WITH THIS TROUGH SHOULD STRETCH FROM WI SWWD ACROSS NRN
MO AND INTO NRN OK/TX PANHANDLE BY LATE THU AFTERNOON. MOST OF THE
STRONG-SEVERE CONVECTION WILL BE LOCATED NEAR THIS FRONT.
...WRN GREAT LAKES SWWD INTO THE MIDDLE MS RIVER VALLEY...
WED NIGHT CONVECTION OVER THE MIDDLE MO RIVER VALLEY SHOULD SHIFT
EWD INTO PORTIONS OF ERN IA/SERN MN/WRN WI EARLY IN THE PERIOD...
ALONG THE WRN EDGE OF 40-50 KT LOW LEVEL JET. THOUGH SOME MARGINAL
SEVERE HAIL IS POSSIBLE DURING THE MORNING WITH THESE STORMS... MAIN
SEVERE POTENTIAL IS LIKELY DURING THE AFTERNOON AND EVENING HOURS.
IT IS UNCLEAR WHETHER THE MORNING CONVECTION WILL BE MAINTAINED EWD
OR STORMS WILL REDEVELOP ALONG REMNANT BOUNDARY/FRONT...BUT IN
EITHER CASE...STORMS SHOULD REINTENSIFY OR DEVELOP BY MID AFTERNOON
FROM WI SWWD INTO NRN MO. WARMING OF DEEP AND MOIST BOUNDARY LAYER
WILL YIELD MLCAPES FROM 2000-3000 J/KG. DEEP LAYER SHEAR NEAR 50 KT
ALONG WITH UNIDIRECTIONAL SWLY WINDS WILL BE FAVORABLE FOR
THUNDERSTORM LINES/BOWS TO EVOLVE. THE STRONG INSTABILITY SHOULD
RESULT IN HAIL...THOUGH THE EXPECTED LINEAR NATURE OF THE CONVECTION
ALONG WITH RAPID ENEWD MOTION... GIVEN 60-70 KT MID LEVEL
WINDS...POINTS TO WIND DAMAGE BEING THE PRIMARY THREAT. ASSUMING THE
MORNING CONVECTION DOES NOT INHIBIT SURFACE DESTABILIZATION...
PORTIONS OF ERN WI/NRN IL AND SERN IA COULD BE UPGRADED TO A
MODERATE RISK IN LATER OUTLOOKS.
...SRN/ERN KS...NRN OK AND SWRN MO...
STRONG CAP IS EXPECTED TO LIMIT CONVECTIVE DEVELOPMENT ACROSS THIS
AREA UNTIL LATE AFTERNOON. THIS WILL ALLOW TEMPERATURES TO WARM INTO
THE 90S...AND WHEN COMBINED WITH LOWER 70S DEWPOINTS... MLCAPES
SHOULD RANGE FROM 2500-3500 J/KG BY LATE AFTERNOON. THE CAP IS
LIKELY TO BE BROKEN BY STRONG HEATING/CONVERGENCE NEAR FRONT ALONG
WITH UVV LOCATED WITH RIGHT ENTRANCE REGION OF UPPER JET...LOCATED
OVER MID/UPPER MS VALLEY. ONCE STORMS DEVELOP... VEERING WIND
PROFILES IN THE LOWER 3 KM AND STRONG INSTABILITY WILL BE FAVORABLE
FOR INTENSE SUPERCELLS. THOUGH A TORNADO OR TWO MIGHT BE
POSSIBLE...THE COMBINATION OF WEAK LOW LEVEL WINDS/SHEAR AND 20-25F
TEMPERATURE-DEWPOINT SPREADS SUGGEST VERY LARGE HAIL AND WIND DAMAGE
WILL BE THE MAIN THREATS. SLIGHTLY ELEVATED STORMS...WITH SEVERE
HAIL...MAY ALSO DEVELOP OVERNIGHT ACROSS PORTIONS OF ERN/SRN KS AS
LLJ STRENGTHENS AND RESULTS IN STRONG WAA NORTH OF COLD FRONT.
...MN...
VERY COLD TEMPERATURES ALOFT AND APPROACHING UPPER LOW WILL RESULT
IN SUFFICIENT INSTABILITY AND LIFT FOR THUNDERSTORMS TO DEVELOP
DURING THE AFTERNOON HOURS. DEEP LAYER SHEAR AT 30-40 KT COMBINED
WITH STEEP LOW/MID LEVEL LAPSE RATES MAY SUPPORT A FEW STORMS WITH
HAIL AND STRONG WIND GUSTS.
..IMY.. 06/11/2008
CLICK TO GET WUUS02 PTSDY2 PRODUCT
NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z
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