MESOSCALE DISCUSSION 1177
   NWS STORM PREDICTION CENTER NORMAN OK
   0502 PM CDT WED JUN 17 2009
   
   AREAS AFFECTED...WRN AND CENTRAL SD/NWRN AND N CENTRAL NEB
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 172202Z - 172330Z
   
   SEVERE/ISOLATED TORNADO POTENTIAL SHOULD INCREASE OVER THE NEXT FEW
   HOURS -- POSSIBLY REQUIRING NEW WW ISSUANCE.
   
   LATEST SURFACE ANALYSIS INDICATES A WEAK DRYLINE ACROSS SWRN SD W OF
   THE BLACK HILLS...AND EXTENDING SWD INTO THE WRN NEB PANHANDLE. 
   LATEST KUDX /RAPID CITY SD/ WSR-88D REFLECTIVITY LOOP CONFIRMS THIS
   BOUNDARY LOCATION.  
   
   WHILE INSTABILITY REMAINS MODEST ACROSS THIS REGION...A WELL-DEFINED
   SHORT-WAVE TROUGH MOVING NEWD ACROSS CO/SWRN WY TOWARD THIS AREA
   SHOULD SUPPORT AN INCREASE IN CONVECTION OVER THE NEXT FEW HOURS. 
   WITH ENHANCED SWLY MID-LEVEL FLOW ACCOMPANYING THIS FEATURE...SHEAR
   WILL BECOME INCREASINGLY-SUPPORTIVE OF ORGANIZED/SEVERE STORMS. 
   ALONG WITH THREATS FOR ISOLATED DAMAGING WINDS AND HAIL WITH
   STRONGER STORMS...LOCAL AREAS OF SELY LOW-LEVEL FLOW -- INCLUDING
   INVOF THE BLACK HILLS -- COULD SUPPORT A LOCALLY-ENHANCED THREAT FOR
   ISOLATED TORNADOES.  IF STORMS INCREASE SUFFICIENTLY IN COVERAGE AS
   CURRENTLY ANTICIPATED...WW COULD BE REQUIRED.
   
   ..GOSS.. 06/17/2009
   
   
   ATTN...WFO...FSD...ABR...LBF...UNR...CYS...
   
   LAT...LON   43329803 42399864 42380320 43750341 44760396 45740220
               45400027 43329803