MESOSCALE DISCUSSION 1814
   NWS STORM PREDICTION CENTER NORMAN OK
   0210 PM CDT SAT AUG 31 2013

   AREAS AFFECTED...PORTIONS ERN DAKOTAS AND MN.

   CONCERNING...SEVERE POTENTIAL...WATCH LIKELY 

   VALID 311910Z - 312115Z

   PROBABILITY OF WATCH ISSUANCE...80 PERCENT

   SUMMARY...SVR THREAT IS FCST TO INCREASE THROUGH AFTN...WITH INITIAL
   MIXTURE OF CONVECTIVE MODES POSSIBLE...INCLUDING
   SUPERCELLS...EVENTUALLY EVOLVING INTO QUASI-LINEAR AND CLUSTERED
   SYSTEMS. ALL SVR MODES ARE POSSIBLE DURING FIRST FEW HOURS OF THIS
   REGIME...EVOLVING TO WIND-DOMINANT.  WW LIKELY WILL BE REQUIRED OVER
   THIS AREA DURING NEXT 1-2 HOURS.

   DISCUSSION...SFC MESOANALYSIS SHOWED COLD FRONT FROM PEMBINA COUNTY
   ND SWWD ACROSS PIR AREA...FCST TO MOVE EWD ACROSS DISCUSSION AREA. 
   LARGE AREA OF MIDLEVEL CONVECTION AND ASSOCIATED BKN-OVC CLOUD COVER
   IS MOVING EWD ACROSS N-CENTRAL/NERN SD...ERN ND AND NWRN MN AT ABOUT
   30 KT...SOMEWHAT OUTPACING SFC COLD FRONT.  HOWEVER...SOME OF THIS
   CLOUD/PRECIP MASS REMAINS BEHIND FRONT...AND BULK OF CLOUD AREA
   AHEAD OF FRONT WILL CONTINUE TO INHIBIT BOTH PACE AND MAGNITUDE OF
   DIABATIC SFC HEATING IN WARM SECTOR.  RELATED WEAKENING OF
   PREFRONTAL MLCINH IS GRADUAL...BASED ON MODIFIED RAOBS AND FCST
   SOUNDINGS...BUT SHOULD ALLOW RELATIVELY UNIMPEDED/SFC-BASED
   EFFECTIVE INFLOW PARCELS BY ABOUT 21Z.  AS SUCH...WIDELY SCATTERED
   TSTMS ALREADY EVIDENT WITHIN CLOUD/PRECIP PLUME MAY BECOME SFC-BASED
   IN SITU.  ADDITIONAL DEVELOPMENT ALSO IS POSSIBLE ALONG COLD FRONT
   ITSELF...AS WELL AS AREAS OF DIFFERENTIAL HEATING ALONG SRN/ERN RIM
   OF CLOUD/PRECIP MASS.  

   SFC MOIST AXIS...WITH PATCHY CONFIGURATION OF MOSTLY MID-UPPER 60S F
   SFC DEW POINTS...WAS DRAWN JUST AHEAD OF FRONT OVER ND AND SWD
   ACROSS ERN SD NEAR MHE/YKN AREA...WHERE LOW-70S VALUES WERE
   OBSERVED.  AXIS SHOULD SHIFT EWD AHEAD OF FRONT AMIDST SSWLY/SWLY
   SFC FLOW.  RELATIVELY VEERED/5-10 KT SFC WINDS WILL LIMIT LOW-LEVEL
   SRH/CONVERGENCE...HOWEVER DEEP SHEAR STILL WILL SUPPORT POTENTIAL
   FOR SUPERCELLS AND FOR BOWING OF ANY QUASI-LINEAR MODES.  DEEP SHEAR
   OVER ERN ND AND NRN MN SHOULD INCREASE WITH APCH OF HEIGHT-GRADIENT
   ENHANCEMENTS PRECEDING SK SHORTWAVE TROUGH.  THIS SHOULD CONTRIBUTE
   TO EFFECTIVE-SHEAR MAGNITUDES INCREASING WITH TIME TO 45-55 KT RANGE
   OVER MORE OF ERN ND/NWRN MN AND 35-45 KT ELSEWHERE.

   ..EDWARDS/GOSS.. 08/31/2013


   ATTN...WFO...DLH...MPX...FGF...FSD...ABR...BIS...

   LAT...LON   44679908 47469755 49009702 48989509 49369510 49379494
               49359493 49289479 49169482 48939469 48809470 48729455
               48709430 48659424 48639386 48539380 48539351 48619342
               48619297 48539266 48419249 48229234 48329229 48349205
               48069155 48259088 47439107 46709217 45689289 44249369
               43589516 43529658 43639937 44679908