Aug 30, 2013 0600 UTC Day 1 Convective Outlook

DAY 1 CONVECTIVE OUTLOOK  

   NWS STORM PREDICTION CENTER NORMAN OK
   1250 AM CDT FRI AUG 30 2013

   VALID 301200Z - 311200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS OVER A PORTION OF WRN AND CNTRL
   ND...

   ...SYNOPSIS...

   A TYPICAL LATE SUMMER PATTERN WILL PERSIST INTO FRIDAY WITH AN UPPER
   RIDGE CENTERED FROM THE SRN/CNTRL PLAINS INTO THE CNTRL
   ROCKIES...KEEPING THE BELT OF STRONGER WLYS ACROSS THE NRN TIER
   STATES. UPPER TROUGH EMBEDDED WITHIN THIS BELT OF STRONGER FLOW NOW
   MOVING INTO THE PACIFIC NW WILL ADVANCE THROUGH THE SWRN CANADIAN
   PROVINCES. FARTHER EAST...THE SHORTWAVE TROUGH NEAR THE ARROWHEAD OF
   MN WILL CONTINUE ESEWD THROUGH THE GREAT LAKES REGION DURING THE DAY
   AND INTO THE NERN STATES FRIDAY NIGHT. THIS FEATURE WILL FORCE A
   COLD FRONT SWD THROUGH THE GREAT LAKES AREA WITH TRAILING PORTIONS
   LIKELY TO STALL OVER THE CNTRL PLAINS. FARTHER WEST...A LEE TROUGH
   WILL SETUP ACROSS THE NRN HIGH PLAINS WITH A COLD FRONT ADVANCING
   SEWD THROUGH MT IN ASSOCIATION WITH THE UPPER TROUGH MOVING THROUGH
   THE SWRN CANADIAN PROVINCES.  

   ...NRN HIGH PLAINS...

   LOW-LEVEL WINDS WILL SHIFT TO SELY IN POST FRONTAL REGIME WEST OF
   SFC RIDGE MOVING THROUGH ERN CANADA. THIS WILL MAINTAIN UPPER 50S TO
   60F DEWPOINTS OVER THE NRN HIGH PLAINS EAST OF LEE TROUGH BENEATH
   STEEP MID-LEVEL LAPSE RATES. SFC HEATING WILL DESTABILIZE THE
   BOUNDARY LAYER AND CONTRIBUTE TO AXIS OF MODERATE INSTABILITY
   /1500-2000 J/KG MLCAPE/ ACROSS THE WRN DAKOTAS. UPPER RIDGE AXIS
   SHOULD DEAMPLIFY OVER THE NRN PLAINS AS SHORTWAVE TROUGH OVER THE
   PACIFIC NW MOVES THROUGH SWRN CANADA. SYNOPTIC FORCING FOR ASCENT
   WILL REMAIN WEAK OVER THE HIGH PLAINS...AND THERE IS SOME CONCERN
   THAT STORM COVERAGE COULD REMAIN LIMITED. HOWEVER...DEEP MIXING AND
   CONVERGENCE ALONG PRE-FRONTAL/LEE TROUGH MAY BE SUFFICIENT FOR A FEW
   STORMS TO DEVELOP DURING THE AFTERNOON. OTHER STORMS MAY INITIATE
   OVER THE HIGHER TERRAIN OF NRN WY INTO MT AND MOVE INTO THE HIGH
   PLAINS. WIND PROFILES WILL STRENGTHEN ALONG NRN PERIPHERY OF
   DEAMPLIFYING UPPER RIDGE WITH 35-40 KT EFFECTIVE SHEAR SUPPORTIVE OF
   SUPERCELLS. ISOLATED LARGE HAIL WILL BE THE MAIN THREATS THROUGH MID
   EVENING.  

   ...GREAT LAKES AND OH VALLEY AREA...

   SHORTWAVE TROUGH NOW OVER THE UPPER MS VALLEY WILL SHIFT SEWD
   THROUGH THE GREAT LAKES REGION DURING THE DAY ATTENDED BY A SWD
   ADVANCING COLD FRONT. THE MOIST WARM SECTOR WILL DESTABILIZE SOUTH
   OF THIS BOUNDARY WITH MLCAPE FROM 2000-2500 J/KG POSSIBLE.
   HOWEVER...THE DEEPER FORCING AND BELT OF STRONGER FLOW ALOFT
   ATTENDING THE SHORTWAVE TROUGH WILL TEND TO REMAIN NORTH AND SHIFT
   EAST OF WHERE STRONGER DESTABILIZATION IS OCCURRING.
   NEVERTHELESS...A FEW STORMS WILL LIKELY REDEVELOP ALONG THE SWD
   ADVANCING COLD FRONT DURING THE AFTERNOON. WIND PROFILES WITH
   VERTICAL SHEAR FROM 25-35 KT SHOULD GENERALLY PROMOTE
   MULTICELLS...BUT THE THERMODYNAMIC ENVIRONMENT MAY SUPPORT SOME
   THREAT FOR ISOLATED STRONG TO DAMAGING WIND GUSTS AND HAIL. WILL
   MAINTAIN 5% SEVERE PROBABILITIES THIS OUTLOOK...BUT A CATEGORICAL
   RISK MAY BE NEEDED IN LATER UPDATES.

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