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Mesoscale Discussion 686
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   MESOSCALE DISCUSSION 0686
   NWS STORM PREDICTION CENTER NORMAN OK
   1251 PM CDT SUN MAY 17 2015

   AREAS AFFECTED...NRN IA THROUGH SRN AND CNTRL MN

   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

   VALID 171751Z - 171945Z

   PROBABILITY OF WATCH ISSUANCE...40 PERCENT

   SUMMARY...STORMS ARE EXPECTED TO UNDERGO SOME STRENGTHENING THIS
   AFTERNOON FROM NRN IA THROUGH SRN AND CNTRL MN. ACTIVITY WILL POSE
   MODEST THREAT FOR MAINLY LOCALLY STRONG WIND GUSTS AND MARGINALLY
   SEVERE HAIL. GIVEN THE SOMEWHAT LIMITED NATURE OF THE THREAT...ANY
   WW ISSUANCE WILL BE DRIVEN BY CONVECTIVE TRENDS.

   DISCUSSION...THUNDERSTORMS ARE DEVELOPING THIS AFTERNOON FROM SWRN
   MN THROUGH WRN IA IN RESPONSE TO ASCENT ACCOMPANYING VORTICITY
   MAXIMA MOVING NEWD THROUGH IA AND ANOTHER SUCH FEATURE OVER ERN SD.
   A WEAK COLD FRONT EXTENDS FROM A SFC LOW OVER NERN SD SWD THROUGH
   ERN SD AND ERN NEB. DIABATIC WARMING OF THE SFC LAYER IS
   DESTABILIZING THE ATMOSPHERE...BUT MODEST LOW-LEVEL MOISTURE AND
   WEAK MID-LEVEL LAPSE RATES SHOULD LIMIT MLCAPE TO AOB 1000 J/KG.
   MOREOVER...VERTICAL SHEAR PROFILES ARE UNIDIRECTIONAL SLY FROM 30-40
   KT WITH SMALL 0-2 KM HODOGRAPHS. THE HAIL THREAT /WHILE NOT
   NEGLIGIBLE/ SHOULD REMAIN SOMEWHAT LIMITED BY POOR LAPSE RATES AND
   MODEST INSTABILITY. WHILE A TORNADO OR TWO WILL BE POSSIBLE...SMALL
   LOW-LEVEL HODOGRAPHS WILL TEND TO REDUCE OVERALL TORNADO POTENTIAL.
   THESE LIMITING FACTORS SUGGEST THE PRIMARY THREAT SHOULD BE LOCALLY
   STRONG WIND GUSTS AS LOW-LEVEL LAPSE RATES CONTINUE TO STEEPEN.

   ..DIAL/THOMPSON.. 05/17/2015


   ATTN...WFO...DLH...ARX...MPX...DMX...FGF...FSD...

   LAT...LON   44719575 45919604 46189390 44159261 42489283 41969553
               43479565 44719575 

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Page last modified: May 17, 2015
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