SPC AC 170731

   DAY 3 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0231 AM CDT WED JUL 17 2013

   VALID 191200Z - 201200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS LOWER MI AND THE UPPER MIDWEST
   TO MAINE...

   ...SYNOPSIS...
   MID/UPPER LEVEL FLOW WILL CONTINUE TO STRENGTHEN AND AMPLIFY ACROSS
   THE GREAT LAKES AND NORTHEAST THROUGH FRIDAY AS MUCH WEAKER AND
   GENERALLY NONDESCRIPT FLOW PERSISTS OVER MUCH OF THE REST OF THE
   CONUS. ASSOCIATED WITH STRONG HEIGHT FALLS ACROSS ONTARIO AND
   QUEBEC...A SHARP COLD FRONT IS FORECAST TO SPREAD EAST FROM THE
   NRN/UPPER GREAT LAKES TO THE ST. LAWRENCE VALLEY DURING THE PERIOD.
   ORGANIZED SEVERE STORM POTENTIAL WILL BE ASSOCIATED WITH THIS
   FRONTAL ADVANCE AND WILL BE GREATEST ACROSS LOWER MI...AND PERHAPS
   EXTENDING FROM THE UPPER MIDWEST TO NRN NEW ENGLAND THROUGH EARLY
   SATURDAY.

   ...MI TO NRN MAINE...
   DEEP-LAYER LIFT ALONG AND AHEAD OF ADVANCING COLD FRONT SHOULD BE
   SUSTAINED BY 12H 500MB HEIGHT FALLS OF AROUND 30-60M. ASCENT ALONG
   THE ADVANCING BOUNDARY IS LIKELY TO COINCIDE WITH STRONGEST
   INSTABILITY ACROSS PARTS OF LOWER MI THROUGH THE AFTERNOON AND
   EVENING. IT IS IN THIS REGION WHERE STEEPER MID LEVEL LAPSE RATES
   WILL CONTRIBUTE TO ROBUST CONVECTIVE UPDRAFTS AS POTENTIALLY STRONG
   LOW LEVEL JET APPROACHING 40KT COULD ENHANCE LOW LEVEL SHEAR AND
   RESULTANT TORNADO/HIGH WIND POTENTIAL...IN ADDITION TO LARGE HAIL.

   OVERALL TIMING OF STRONGER FORCING ASSOCIATED WITH THE FRONT AND
   DEVELOPING UPPER TROUGH...COINCIDENT WITH MAXIMUM IN DIURNAL
   DESTABILIZATION...IS LESS CERTAIN WITH EWD EXTENT INTO NRN NEW
   ENGLAND. WHILE FORECAST LAPSE RATES APPEAR SOMEWHAT MORE LIMITED IN
   THE CORRIDOR EXTENDING NEWD FROM THE ERN GREAT LAKES...DEEP-LAYER
   FLOW IS EXPECTED TO BECOME INCREASINGLY STRONG WITH TIME.
   STRENGTHENING UNIDIRECTIONAL SHEAR AND PERSISTENT CHANCE OF AT LEAST
   SCATTERED CONVECTION SUGGESTS A FEW LINES AND/OR BANDS OF STORMS
   WITH SOME DAMAGING WIND POTENTIAL THROUGH FRIDAY AND PERHAPS INTO
   EARLY SATURDAY.

   ..CARBIN.. 07/17/2013

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   NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 0730Z