MESOSCALE DISCUSSION 2015
   NWS STORM PREDICTION CENTER NORMAN OK
   0206 PM CDT THU AUG 18 2005
   
   AREAS AFFECTED...WRN SD...ERN WY AND NWRN NEB PANHANDLE
   
   CONCERNING...SEVERE THUNDERSTORM POTENTIAL 
   
   VALID 181905Z - 182100Z
   
   TSTMS DEVELOPING OVER THE BLACK HILLS MAY POSE AN ISOLATED SVR
   THREAT IN THE NEXT HR OR SO. ADDITIONAL TSTMS ARE EXPECTED TO
   DEVELOP EITHER ALONG STATIONARY FRONTAL BOUNDARY EXTENDING E-W
   ACROSS NERN/ECENTRAL WY INTO WCENTRAL SD AND/OR MOVE OUT OF CENTRAL
   WY WHILE INTENSIFYING. DESPITE MODEST DEEP LAYER SHEAR...OVERALL
   MARGINAL INSTABILITY SHOULD LIMIT THE SEVERE THREAT TO ISOLATED
   OCCURRENCES OVER THE NEXT FEW HOURS. THUS WW ISSUANCE REMAINS
   UNCERTAIN ATTM.
   
   LATEST SATELLITE/RADAR IMAGERY INDICATE TSTMS DEVELOPING OVER THE
   BLACK HILLS. ALTHOUGH LOW LEVEL WINDS REMAINS NNWLY...MODERATE
   UPSLOPE COMPONENT TO LOW LEVEL FLOW ALONG WITH ADDITIONAL AIRMASS
   DESTABILIZATION SHOULD SUPPORT CONTINUED DEVELOPMENT/
   INTENSIFICATION OF CONVECTION OVER THE NRN BLACK HILLS AREA DURING
   THE NEXT FEW HOURS. LOW LEVELS REMAIN SOMEWHAT CAPPED EAST OF THE
   BLACK HILLS /LOWER ELEVATIONS/...WITH OVER 100 J/KG OF MLCINH PER
   RECENT OBJECTIVE ANALYSIS. THUS CONVECTION WILL LIKELY STRUGGLE TO
   MOVE OUT OF THE HIGHER TERRAIN THROUGH 21Z.  WITH 30-40 KTS OF DEEP
   LAYER SHEAR AND 1000-1200 J/KG OF MUCAPE /PER RECENT FCST SOUNDINGS
   AND MBW PROFILER DATA/ ISOLATED SVR HAIL MAY BE POSSIBLE WITH THE
   STRONGEST STORMS. FARTHER WEST...BASED ON RAWS/ASOS REPORTS...THE
   SFC FRONTAL BOUNDARY HAS BECOME STATIONARY FROM NRN NATRONA COUNTY
   WY ESEWD TO DAWES COUNTY IN THE NEB PANHANDLE. SUFFICIENT
   CONVERGENCE AND ADDITIONAL HEATING/MINIMAL CINH ALONG THIS BOUNDARY
   SUGGESTS THAT ISOLATED TSTM DEVELOPMENT IS POSSIBLE IN THE NEXT FEW
   HRS. IN ADDITION...HIGH BASED CONVECTION THAT IS OCCURRING TO THE
   WEST OF THE LARAMIE MTNS MAY INTENSIFY AS IT ENCOUNTERS THE BETTER
   INSTABILITY OVER ERN WY INTO THE FAR WRN NEB PANHANDLE BY MID
   AFTERNOON. FCST SOUNDINGS IN ERN WY/NWRN NEB PANHANDLE BASED ON
   CURRENT DEWPT FIELDS INDICATE AROUND 1200 J/KG OF MUCAPE SHOULD
   EXIST BY 21Z. WITH AROUND 40 KTS OF DEEP LAYER SHEAR...THE
   ENVIRONMENT WILL BE SUPPORTIVE OF AN ISOLATED SVR HAIL THREAT AS
   WELL.
   
   ..CROSBIE.. 08/18/2005
   
   
   ATTN...WFO...LBF...UNR...CYS...BYZ...RIW...
   
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