MESOSCALE DISCUSSION 1836
   NWS STORM PREDICTION CENTER NORMAN OK
   0401 AM CDT MON JUL 21 2008
   
   AREAS AFFECTED...SE SD...NE NEB...NW IA
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 210901Z - 211030Z
   
   AN ISOLATED SEVERE THREAT WILL LIKELY CONTINUE SEWD ACROSS SERN SD
   OVER THE NEXT FEW HOURS. WIND DAMAGE AND HAIL WILL BE LIKELY AND A
   WW MAY NEED TO BE ISSUED SHORTLY ACROSS THE REGION.
   
   LATEST WATER VAPOR IMAGERY SHOWS A WELL-FOCUSED SHORTWAVE TROUGH
   OVER SCNTRL ND WITH A BAND OF STRONG LIFT LOCATED AHEAD OF THE
   FEATURE ACROSS ERN SD. AN ELEVATED SEVERE STORM IN ERN SD IS LOCATED
   ALONG THE LEADING EDGE OF ASCENT AND IS RIDING SEWD ALONG A GRADIENT
   IN INSTABILITY EXTENDING SEWD INTO NW IA. MUCAPE VALUES ALONG THIS
   AXIS ARE ESTIMATED BY THE RUC IN THE 1500 TO 2000 J/KG RANGE AND
   THIS SHOULD SUSTAIN THE CONVECTION SEWD OVER THE NEXT 2 TO 4 HOURS.
   STEEP MID-LEVEL LAPSE RATES...COLD TEMPS ALOFT ASSOCIATED WITH THE
   UPPER-LEVEL TROUGH AND STRONG VERTICAL SHEAR SHOULD SUPPORT A THREAT
   FOR HAIL. WIND DAMAGE WILL ALSO BE POSSIBLE IF THE STORMS CAN
   EFFECTIVELY TRANSPORT MID-LEVEL FLOW THROUGH THE CAPPING INVERSION.
   
   ..BROYLES.. 07/21/2008
   
   
   ATTN...WFO...FSD...OAX...ABR...
   
   42269639 42299746 42969815 43979867 44429863 44649822
   44539779 44339744 43979687 43639651 43089590 42749589