DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 121600
SWODY1
SPC AC 121558

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1058 AM CDT MON SEP 12 2011

VALID 121630Z - 131200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER PORTIONS OF WI AND UPPER
MI...

...MI/WI...
MORNING SATELLITE LOOPS SHOW A WELL-DEFINED MID LEVEL SHORTWAVE
TROUGH MOVING ACROSS MANITOBA/ND. THIS FEATURE WILL TRACK ACROSS
THE UPPER GREAT LAKES THIS AFTERNOON AND EVENING SUPPORTING A RISK
OF SCATTERED THUNDERSTORMS. ACTIVITY IS LIKELY TO FORM NEAR THE
ASSOCIATED SURFACE COLD FRONT AS IT MOVES ACROSS LAKE SUPERIOR AND
WESTERN UPPER MI LATER TODAY. FAVORABLE DEEP LAYER VERTICAL SHEAR
AND SUFFICIENT CAPE WILL PROMOTE ORGANIZED MULTICELL AND SUPERCELL
STRUCTURES CAPABLE OF LARGE HAIL AND DAMAGING WINDS. VEERED LOW
LEVEL WINDS AND SOMEWHAT LIMITED LOW LEVEL MOISTURE SHOULD LESSEN
THE TORNADO RISK. STORMS WILL THEN TRACK EAST-SOUTHEASTWARD ACROSS
MUCH OF UPPER MI AND APPROACH NORTHERN LOWER MI THIS EVENING.
UNCERTAINTY ALSO EXISTS HOW FAR SOUTHWEST STORMS MAY DEVELOP ALONG
THE FRONT INTO WI. GIVEN TRENDS IN NEW NAM SOLUTION AND SOME OF THE
MESOSCALE MODELS...HAVE EXTENDED SLIGHT RISK AREA INTO CENTRAL WI TO
ACCOUNT FOR THIS THREAT.

...AZ...
SOUTHWEST FLOW ALOFT REMAINS OVER AZ TODAY WITH A PLUME OF MORE RICH
MID LEVEL MOISTURE EVIDENT IN MORNING SATELLITE IMAGERY. INCREASED
CLOUDS AND WEAKER LAPSE RATES SHOULD LIMIT THE OVERALL THREAT OF
SEVERE STORMS TODAY. HOWEVER...LOCALLY GUSTY/DAMAGING WINDS CANNOT
BE RULED OUT THIS AFTERNOON IN STORMS THAT FORM OVER THE CENTRAL AZ
WHERE STEEP LOW LEVEL LAPSE RATES WILL BE PRESENT.

...CAROLINAS...
A SHORTWAVE TROUGH IS MOVING ACROSS GA/SC AT THIS TIME...AND SHOULD
HELP TO PROMOTE SCATTERED AFTERNOON THUNDERSTORMS ALONG THE NC/SC
COAST. LOW LEVEL WINDS ARE WEAK AND LAPSE RATES ARE POOR.
NEVERTHELESS...A FEW OF THE STRONGER STORMS MAY PRODUCE LOCALLY
GUSTY WINDS AND HAIL BEFORE MOVING OFFSHORE.

..HART/SMITH.. 09/12/2011

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