MESOSCALE DISCUSSION 1220
   NWS STORM PREDICTION CENTER NORMAN OK
   0627 PM CDT WED JUN 20 2007
   
   AREAS AFFECTED...CNTRL AND ERN SD
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 202327Z - 210100Z
   
   TSTM POTENTIAL APPEARS TO BE INCREASING ALONG FRONT AND AREA IS
   BEING MONITORED FOR A WW.
   
   CURRENT SURFACE AND VISIBLE SATELLITE OBSERVATIONS INDICATE
   QUASI-STATIONARY BOUNDARY EXTENDING FROM VICINITY OF ONGOING TSTMS N
   OF MSP WSWWD TO NEAR ATY...HON AND PIR WITH GREATEST CONSOLIDATION
   OF CUMULUS DEVELOPMENT NOTED FROM DEUEL TO BEADLE COUNTIES IN ERN
   SD.  AIR MASS ALONG AND S OF THIS BOUNDARY HAS BECOME MODERATELY TO
   STRONGLY UNSTABLE /MLCAPES OF 2000-3500 J PER KG/ EARLY THIS EVENING
   OWING TO MOIST BOUNDARY LAYER CONDITIONS AND STEEP LAPSE RATES. 
   
   RUC OBJECTIVE FIELDS INDICATE THAT THE CAP HAS WEAKENED...HOWEVER
   LOW-LEVEL CONVERGENCE REMAINS QUITE MARGINAL ATTM.  LATEST SHORT
   TERM MODEL GUIDANCE SUGGESTS THAT TSTM DEVELOPMENT WILL BECOME
   INCREASINGLY LIKELY BETWEEN 21/00-02Z OVER PARTS OF ERN SD...PERHAPS
   AS SLY LLJ INCREASES AND ENHANCES CONVERGENCE ALONG FRONTAL ZONE.  
   
   CURRENT WOOD LAKE MN PROFILER APPEARS TO BE REPRESENTATIVE OF THE
   KINEMATIC ENVIRONMENT ALONG FRONTAL ZONE WITH GENERALLY A LINEAR
   HODOGRAPH WITH 30-40 KT OF DEEP LAYER SHEAR THROUGH THE LOWEST 6 KM
   AGL.  SHOULD STORMS DEVELOP AND BECOME SUSTAINED...POTENTIAL WILL
   EXIST FOR SPLITTING SUPERCELLS CAPABLE OF VERY LARGE HAIL...DAMAGING
   WINDS AND PERHAPS A TORNADO OR TWO.
   
   ..MEAD.. 06/20/2007
   
   
   ATTN...WFO...FSD...ABR...
   
   44430036 44670008 44969927 44999832 45069748 45099705
   44949665 44589651 44119682 43739799 43699880 43979996