MESOSCALE DISCUSSION 1409
   NWS STORM PREDICTION CENTER NORMAN OK
   0729 PM CDT THU JUL 02 2009
   
   AREAS AFFECTED...SERN MT/ERN WY/WRN SD/WRN NEB/NERN CO
   
   CONCERNING...SEVERE THUNDERSTORM WATCH 538...
   
   VALID 030029Z - 030130Z
   
   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 538
   CONTINUES.
   
   OBJECTIVE ANALYSES INDICATED A MODERATELY UNSTABLE AIR MASS
   EXTENDING FROM ERN CO NWD THROUGH WRN NEB TO SWRN SD EARLY THIS
   EVENING WITH EFFECTIVE BULK SHEAR VALUES AROUND 40-50 KT OVER MUCH
   OF WW 538 AND 30-40 KT S OF THIS WATCH INTO WRN NEB/NERN CO.
   SHORTWAVE TROUGH EVIDENT IN WATER VAPOR IMAGERY AND PER 21Z RUC
   TRACKING E/SEWD INTO SWRN ND/WRN SD WILL CONTINUE TO SUPPORT TSTM
   DEVELOPMENT WITHIN WW 538...WHILE A WEAKER IMPULSE CONTINUES TO
   SUPPORT DEVELOPMENT ACROSS WRN NEB/NERN CO. 
   
   00Z RAPID CITY SOUNDING INDICATED BOUNDARY LAYER IS BEGINNING TO
   STABILIZE AND/OR HAS BEEN CONVECTIVELY OVERTURNED OVER MUCH OF WRN
   SD...WITH DIMINISHING INSTABILITY VALUES ACROSS SERN MT/NERN WY. 
   ASIDE FROM THE STORM IN FAR EAST CENTRAL WY /NIOBRARA COUNTY/ AND
   ACTIVITY S OF WW 538...MUCH OF WRN SD/NERN WY AND SERN MT CAN BE
   CANCELLED FROM THIS WATCH.  MEANWHILE...SHORT TERM MODELS SUGGEST
   TSTMS S OF WW 538 SHOULD REMAIN CONFINED FROM NERN CO INTO WRN NEB
   WHERE ACTIVITY HAS ALREADY DEVELOPED WITH OVERALL SEVERE COVERAGE
   TENDING TO BE ISOLATED.
   
   ..PETERS.. 07/03/2009
   
   
   ATTN...WFO...ABR...BIS...LBF...UNR...GLD...PUB...BOU...CYS...
   BYZ...GGW...RIW...
   
   LAT...LON   39010482 40560478 41800443 43000417 43490709 45000788
               45030677 46260700 46800793 47550783 47900641 47170568
               47760519 47340404 45980384 45910155 44880102 43390090
               42170019 41260030 40400189 39010482