MESOSCALE DISCUSSION 1541
   NWS STORM PREDICTION CENTER NORMAN OK
   0246 PM CDT THU JUL 19 2007
   
   AREAS AFFECTED...WRN/CENTRAL MT...NCENTRAL/NERN WY
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 191946Z - 192215Z
   
   CONVECTION DEVELOPING OVER THE BIG HORN MTNS IS EXPECTED TO CONTINUE
   TO INTENSIFY OVER THE NEXT FEW HOURS AND BEGIN TO POSE A MARGINAL
   SVR THREAT BY 21Z. ADDITIONAL TSTMS ARE EXPECTED TO DEVELOP ALONG A
   LEE TROUGH/DRYLINE ACROSS WCENTRAL/SWRN MT AND ALONG A COLD FRONT
   OVER FAR WRN MT STARTING AROUND 22Z. TRENDS WILL BE MONITORED FOR A
   POSSIBLE WW FOR NRN/WRN PORTIONS OF THE AREA BEFORE THEN.
   
   LATEST SFC ANALYSIS SHOWS AN AREA OF LOW PRESSURE OVER NCENTRAL MT
   /NORTH OF BOZEMAN/. TO THE SOUTH OF THIS LOW...A LEE TROUGH/DRYLINE
   EXTENDS INTO SWRN MT AND NWRN WY. A COLD FRONT EXTENDED SW-NE FROM
   THE LOW INTO ACROSS WRN MT. THE AIRMASS AHEAD OF THIS DRYLINE AND
   EAST OF THE COLD FRONT WAS BECOMING MODERATELY UNSTABLE WITH MLCAPE
   VALUES FROM 1500-2500 J/KG. A FEW MORE HOURS OF HEATING AND
   DESTABILIZATION SHOULD REMOVE THE REMAINING CINH AND SUPPORT
   CONVECTIVE DEVELOPMENT. ALTHOUGH VERTICAL SHEAR REMAINS MARGINAL
   OVER SCENTRAL MT/NCENTRAL WY /20-30 KTS/...STEEP LOW-MID LEVEL LAPSE
   RATES AND HIGH VALUES OF DCAPE /AROUND 1500 J/KG/ WILL SUPPORT
   ISOLATED DMGG WIND GUSTS WITH THE STRONGEST TSTMS. RELATIVELY SLOW
   STORM MOTIONS WILL FAVOR LOCALIZED HEAVY RAINFALL RATES AS WELL.
   FURTHER NORTH...GREATER SHEAR OVER NCENTRAL/WCENTRAL MT WILL FAVOR
   ISOLATED SUPERCELL TSTMS AND POTENTIAL FOR DMGG WIND GUSTS AND A
   MORE ORGANIZED SVR THREAT.
   
   ..CROSBIE.. 07/19/2007
   
   
   ATTN...WFO...UNR...CYS...BYZ...GGW...RIW...TFX...MSO...
   
   48980971 49001219 49041273 48151311 47561355 47051383
   46491326 46741220 46451067 45470970 43840836 43120773
   43200685 43300633 43670476 44310516 45770591 46850680
   48090762 49030842