MESOSCALE DISCUSSION 1654
   NWS STORM PREDICTION CENTER NORMAN OK
   0311 PM CDT MON JUL 18 2011
   
   AREAS AFFECTED...WRN/NRN SOUTH DAKOTA AND ADJACENT NORTH DAKOTA
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 182011Z - 182145Z
   
   TIMING IS STILL SOMEWHAT UNCERTAIN...BUT A WATCH COULD BECOME
   NECESSARY WITHIN THE NEXT HOUR OR TWO.
   
   A WEAK SURFACE LOW IS GRADUALLY DEVELOPING ALONG A SURFACE FRONT
   NEAR THE BLACK HILLS...WITH ISOLATED VIGOROUS STORM DEVELOPMENT
   ALREADY UNDERWAY OFF THE NORTHEASTERN SLOPES OF THE BLACK HILLS. 
   INHIBITION FOR VERY MOIST BOUNDARY LAYER PARCELS NORTH OF THE FRONT
   REMAINS CONSIDERABLE...BUT APPEARS TO BE WEAKENING WITH CONTINUED
   STRONG INSOLATION.  WITH FURTHER BOUNDARY LAYER WARMING THROUGH THE
   21-23Z TIME FRAME...CONVERGENCE AND LOW-LEVEL WARM ADVECTION TO THE
   EAST NORTHEAST OF THE LOW MAY SUPPORT NORTHEASTWARD DEVELOPMENT OF
   ONGOING ACTIVITY...AS WELL AS THE INITIATION OF NEW STORMS...IN THE
   PRESENCE OF MODESTLY STEEP LAPSE RATES AND LARGE CAPE.  CLOCKWISE
   TURNING OF WINDS WITH HEIGHT BENEATH 30-40 KT SOUTHWESTERLY 500 MB
   FLOW SHOULD CONTRIBUTE TO SUFFICIENT SHEAR FOR SUPERCELLS...WITH THE
   RISK FOR LARGE HAIL...PERHAPS A COUPLE OF BRIEF TORNADOES.
   
   ..KERR.. 07/18/2011
   
   
   ATTN...WFO...ABR...BIS...UNR...
   
   LAT...LON   44550396 45240387 45790388 46080314 46200186 45430078
               45090079 44790132 44440273 44310332 44040365 44550396