MESOSCALE DISCUSSION 1712
   NWS STORM PREDICTION CENTER NORMAN OK
   0322 PM CDT TUE AUG 13 2013

   AREAS AFFECTED...PORTIONS OF ERN MT AND WRN ND

   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

   VALID 132022Z - 132245Z

   PROBABILITY OF WATCH ISSUANCE...40 PERCENT

   SUMMARY...THE SVR POTENTIAL MAY INCREASE THROUGH THE AFTERNOON
   HOURS...AND THIS MAY POSSIBLY WARRANT THE ISSUANCE OF A WW.

   DISCUSSION...WIDELY SCATTERED CONVECTION OVER FAR NERN MT APPEARS TO
   BE ENHANCED BY A MINOR MID-LEVEL PERTURBATION -- PERHAPS AIDED BY
   PREVIOUS CONVECTION. ASCENT ACCOMPANYING THIS FEATURE...ALONG WITH
   DIFFERENTIAL HEATING ALONG ITS SRN FRINGES...COULD FOSTER AN
   INCREASE IN CONVECTIVE COVERAGE/INTENSITY WITHIN A CORRIDOR OF
   ENHANCED LOW-LEVEL MOISTURE THAT EXTENDS NNW/SSE ACROSS THE AREA.
   THIS CORRIDOR FEATURES SFC DEWPOINTS IN THE UPPER 50S AND LOWER 60S
   ALONG WITH A PATCHY BOUNDARY-LAYER CUMULUS FIELD PER VIS SATELLITE
   IMAGERY. THIS MOISTURE LIES BENEATH MODESTLY STEEP MID-LEVEL LAPSE
   RATES -- E.G. H7-H5 LAPSE RATES AROUND 7.0-7.5 C/KM PER 12Z GGW RAOB
   DATA. WHILE DEEPER FORCING FOR ASCENT -- ASIDE FROM THE
   AFOREMENTIONED PERTURBATION -- IS RATHER LIMITED PER WATER VAPOR
   LOOPS...THE PRESENCE OF AT LEAST MODERATE INSTABILITY AND AROUND
   20-30 KT OF EFFECTIVE BULK SHEAR MAY BE SUFFICIENT TO SUPPORT A FEW
   SMALL CONVECTIVE CLUSTERS WITH THE POTENTIAL FOR SVR WIND/HAIL. IF
   IT WERE TO APPEAR THAT CONVECTION GROWS UPSCALE AND OFFERS A
   GREATER-COVERAGE SVR THREAT...A WW MAY BECOME WARRANTED.

   ..COHEN/KERR.. 08/13/2013


   ATTN...WFO...BIS...BYZ...GGW...

   LAT...LON   48560412 47440271 46100251 45950409 45180435 45250508
               46620590 48010621 48690569 48560412