Sunday, September 11, 2011

DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 111700
SWODY2
SPC AC 111659

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1159 AM CDT SUN SEP 11 2011

VALID 121200Z - 131200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM NRN WI INTO UPPER MI...

...SYNOPSIS...
A POTENT UPPER SHORTWAVE TROUGH EMBEDDED WITHIN A BROADER TROUGH
WILL MOVE SEWD ACROSS THE NRN PLAINS AND INTO THE UPPER GREAT LAKES
OVERNIGHT. AT THE SURFACE...LOW PRESSURE WILL MOVE FROM THE RED
RIVER VALLEY AT 12Z MON EWD ACROSS SRN ONTARIO THROUGH
EVENING...WITH COLD FRONT TRAILING SWWD ACROSS WI AND INTO SERN MN.
AHEAD OF THIS FRONT...BOUNDARY LAYER DEWPOINTS WILL ONLY BE IN THE
50S F DUE TO TRAJECTORIES OUT OF THE SERN U.S. HIGH.

...MN ARROWHEAD INTO NRN WI AND UPPER MI...
STORMS ARE EXPECTED TO BEGIN OVER THE MN ARROWHEAD BY
AFTERNOON...WHERE FORCING WILL BE MAXIMIZED NEAR THE SURFACE LOW. AS
PEAK HEATING IS ACHIEVED...STORMS WILL SPREAD SEWD INTO NRN WI AND
UPPER MI. ALTHOUGH MOISTURE WILL BE MARGINAL WITH DEWPOINTS IN THE
50S F...STRONG FORCING AND COOLING ALOFT SHOULD LEAD TO A SWATH OF
SEVERE POTENTIAL. SWLY LOW LEVEL WINDS VEERING TO WNWLY AND
INCREASING IN SPEED ALOFT WILL CREATE FAVORABLE HODOGRAPHS FOR
SUPERCELLS CAPABLE OF LARGE HAIL...DAMAGING WINDS. A FEW CELLS COULD
PRODUCE A TORNADO...ESPECIALLY IN CLOSE PROXIMITY TO ANY REMAINING
WARM FRONT WHICH MAY LIE ACROSS UPPER MI.

STORM COVERAGE WITH SRN EXTENT BECOMES MUCH LESS PROBABLE DUE TO
ONLY MARGINAL FORCING NEAR THE COLD FRONT AND CAPPING...BUT WILL
MAINTAIN LOW PROBABILITIES.

..JEWELL.. 09/11/2011

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