Jun 21, 2014 1300 UTC Day 1 Convective Outlook

DAY 1 CONVECTIVE OUTLOOK  

   NWS STORM PREDICTION CENTER NORMAN OK
   0758 AM CDT SAT JUN 21 2014

   VALID 211300Z - 221200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON INTO EARLY
   TONIGHT FOR PARTS OF THE DAKOTAS/NEB TO IA/IL...

   ...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON FOR ERN NC AND
   NE SC...

   ...SUMMARY...
   SEVERAL CLUSTERS OF THUNDERSTORMS...CAPABLE OF PRODUCING SEVERE WIND
   GUSTS AND LARGE HAIL...ARE EXPECTED TODAY INTO TONIGHT ACROSS MUCH
   OF SOUTH DAKOTA AND ADJACENT NORTHERN NEBRASKA AND SOUTHEASTERN
   NORTH DAKOTA. ADDITIONAL STRONG TO SEVERE STORM DEVELOPMENT APPEARS
   POSSIBLE EAST SOUTHEASTWARD ACROSS IOWA TO NORTHERN AND CENTRAL
   ILLINOIS...AND IN A SEPARATE AREA ACROSS EASTERN NORTH CAROLINA AND
   NORTHEAST SOUTH CAROLINA.

   ...NEB/SD/SE ND THIS AFTERNOON INTO EARLY TONIGHT...
   THE OVERNIGHT CONVECTION ACROSS NEB IS NOW WEAKENING NEAR THE KS
   BORDER...WITH DESTABILIZATION EXPECTED THROUGH THIS AFTERNOON ACROSS
   NEB/SD/SRN ND WITH SURFACE HEATING AND A GRADUAL INCREASE IN
   LOW-LEVEL MOISTURE.  STEEP MIDLEVEL LAPSE RATES OBSERVED AT LBF AND
   RAP WILL CONTINUE TO OVERSPREAD NEB/SD TODAY...CONTRIBUTING TO
   MODERATE BUOYANCY BY MID-LATE AFTERNOON /MLCAPE OF 2000-3000 J PER
   KG/.  THIS BUOYANCY...COMBINED WITH EFFECTIVE BULK SHEAR IN THE
   30-40 KT RANGE...WILL SUPPORT A RISK FOR ORGANIZED SEVERE
   STORMS...INCLUDING SUPERCELLS.  THE INITIAL STORMS ARE EXPECTED TO
   FORM THIS AFTERNOON ALONG A SUBTLE BOUNDARY FROM WRN/CENTRAL SD INTO
   SE ND...WHEN SUPERCELLS WITH ISOLATED VERY LARGE HAIL WILL BE MOST
   PROBABLE.  CONVECTION SHOULD THEN GROW INTO ONE OR MORE CLUSTERS
   WHILE MOVING SEWD...WITH AN ATTENDANT RISK FOR DAMAGING WINDS INTO
   THIS EVENING.

   ...IA/IL AREA TODAY...
   A REMNANT MCV FROM OVERNIGHT CONVECTION WILL MOVE EWD/ESEWD FROM
   CENTRAL IA THIS MORNING TO NW IL BY EARLY AFTERNOON.  SURFACE
   HEATING IN CLOUD BREAKS AND A MOIST BOUNDARY LAYER WILL SUPPORT
   MLCAPE APPROACHING 2000 J/KG THIS AFTERNOON IN ADVANCE OF THE MCV. 
   SOME REGENERATION OF CONVECTION WILL BE POSSIBLE DURING THE
   AFTERNOON....WITH AN ASSOCIATED RISK FOR A FEW DAMAGING GUSTS AND
   ISOLATED LARGE HAIL.

   ...ERN NC/NE SC THIS AFTERNOON...
   A WEAK SURFACE FRONT/TROUGH WILL DRIFT SEWD ACROSS THE ERN CAROLINAS
   THIS AFTERNOON IN ASSOCIATION WITH DIFFUSE SPEED MAXIMA MOVING SEWD
   FROM THE OH VALLEY.  THOUGH LAPSE RATES ALOFT ARE NOT PARTICULARLY
   STEEP IN REGIONAL 12Z SOUNDINGS...BOUNDARY LAYER DEWPOINTS NEAR 70 F
   AND DAYTIME HEATING WILL RESULT IN MODERATE BUOYANCY ACROSS THE ERN
   CAROLINAS.  THE COMBINATION OF LOW-LEVEL CONVERGENCE ALONG THE
   SURFACE TROUGH...AS WELL AS LOCAL SEA BREEZE CIRCULATIONS...COULD
   SUPPORT A FEW STORMS CAPABLE OF PRODUCING DAMAGING DOWNBURST WINDS.