SPC AC 031726

   DAY 2 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1226 PM CDT WED SEP 03 2014

   VALID 041200Z - 051200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE UPPER
   MIDWEST...

   ...SUMMARY...
   ISOLATED SEVERE STORMS ARE EXPECTED OVER PARTS OF THE UPPER MIDWEST
   DURING THE DAY AND EVENING ON THURSDAY. STRONG TO LOCALLY SEVERE
   STORMS WILL BE POSSIBLE SOUTHWESTWARD ACROSS THE CENTRAL GREAT
   PLAINS...MAINLY IN THE EVENING.

   ...SYNOPSIS...
   POSITIVE-TILT SHORTWAVE TROUGH WILL MOVE FROM THE INTERNATIONAL
   BORDER OVER THE NRN PLAINS INTO NRN ONTARIO THROUGH EARLY FRI.
   ATTENDANT SURFACE CYCLONE WILL TAKE A SIMILAR TRACK WITH A COLD
   FRONT PUSHING E/S ACROSS THE UPPER MS VALLEY AND CNTRL PLAINS. 

   ...UPPER MIDWEST...
   NEUTRAL TO WEAK MID-LEVEL HEIGHT RISES ARE EXPECTED ACROSS MUCH OF
   THE REGION THROUGH LATE AFTERNOON BASED ON THE POSITIVE-TILT NATURE
   AND TRACK OF THE AFOREMENTIONED SHORTWAVE TROUGH. RATHER WARM 700 MB
   TEMPERATURES OF 12-15 DEG C SHOULD EFFECTIVELY CAP SURFACE-BASED
   STORM DEVELOPMENT THROUGH MOST OF THE DAY S OF THE INTERNATIONAL
   BORDER AREA AS A VERY UNSTABLE AIR MASS RECHARGES IN THE WAKE OF
   CONVECTION ON D1. WHERE LARGE-SCALE ASCENT SHOULD BE MAXIMIZED NEAR
   THE SURFACE CYCLONE TRACK AND ON THE LEADING EDGE OF COOLING
   MID-LEVEL TEMPERATURES...SURFACE-BASED STORMS MAY DEVELOP FROM NERN
   MN INTO WRN UPPER MI. ALTHOUGH THIS CORRIDOR SHOULD BE ON THE FRINGE
   OF LARGE BUOYANCY...VERY STRONG DEEP-LAYER SHEAR PROFILES WOULD BE
   CONDUCIVE TO SUPERCELLS AND FAST-MOVING CLUSTERS CAPABLE OF ALL
   HAZARDS. HAVE EXPANDED SLIGHT RISK TO THE W TO ACCOUNT FOR THIS
   SCENARIO.

   FARTHER S...THE STRENGTH OF THE CAPPING INVERSION RENDERS LOW
   CONFIDENCE IN THE SPATIOTEMPORAL DETAILS OF CONVECTIVE INITIATION.
   CONVERGENCE ALONG THE FRONT IN CONJUNCTION WITH MINOR HEIGHT FALLS
   BY EVENING MAY YIELD ISOLATED STORMS FORMING TOWARDS THE MS AND ST
   CROIX VALLEYS ALONG THE MN/WI BORDER. AMIDST A VERY UNSTABLE AIR
   MASS...SUSTAINED CONVECTION WITHIN THIS REGION COULD RAPIDLY GROW
   INTO SUPERCELLS.

   ...CNTRL PLAINS...
   CONVECTION SHOULD DEVELOP THU EVENING ALONG AND BEHIND THE COLD
   FRONT PUSHING S. WITHIN A NARROW FRONTAL CORRIDOR...COMBINATION OF
   STEEP MID-LEVEL LAPSE RATES AND MODEST EFFECTIVE SHEAR SHOULD
   SUPPORT A FEW SEVERE HAIL AND WIND EVENTS. BUT THE UNDERCUTTING
   NATURE OF THE BOUNDARY AND ANAFRONTAL SETUP WILL SERVE TO LIMIT THE
   OVERALL RISK.

   ..GRAMS.. 09/03/2014

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