MESOSCALE DISCUSSION 0831
   NWS STORM PREDICTION CENTER NORMAN OK
   0547 PM CDT FRI MAY 18 2007
   
   AREAS AFFECTED...SWRN ND INTO NWRN SD
   
   CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 
   
   VALID 182247Z - 190015Z
   
   POTENTIAL FOR A FEW STRONG TO BRIEFLY SEVERE STORMS CAPABLE OF
   LOCALLY GUSTY WINDS AND/OR HAIL WILL EXIST THIS EVENING.  A WW IS
   NOT ANTICIPATED.
   
   RECENT TRENDS IN VISIBLE SATELLITE AND MOSAIC RADAR IMAGERY INDICATE
   A GRADUAL INCREASE IN DEEP CONVECTIVE DEVELOPMENT ALONG COLD FRONT
   FROM HETTINGER AND GRANT COUNTIES ND SWWD INTO HARDING AND PERKINS
   COUNTIES SD.  PRE-FRONTAL AIR MASS IS RELATIVELY HOT WITH
   TEMPERATURES IN THE UPPER 80S TO AROUND 90 F WHICH ARE CONTRIBUTING
   TO STEEP LOW LEVEL LAPSE RATES OF 8.5-9.5 C/KM.  DESPITE MODEST
   BOUNDARY LAYER MOISTURE...THESE LAPSE RATES ARE RESULTING IN A
   MODERATELY UNSTABLE AIR MASS WITH MLCAPES OF 1000-1500 J/KG.
   
   THE PRIMARY FACTOR LIMITING A MORE ORGANIZED SEVERE WEATHER THREAT S
   OF WW 279 APPEARS TO BE THE MARGINAL DEEP LAYER VERTICAL SHEAR. 
   HOWEVER...THE PRESENCE OF DEEP TROPOSPHERIC LAPSE RATES INDICATE THE
   POTENTIAL FOR MARGINALLY SEVERE HAIL AND/OR LOCALLY STRONG WIND
   GUSTS WITH THE MORE INTENSE STORMS.  ANY STORMS THAT DEVELOP SHOULD
   TEND TO WEAKEN AFTER 03-04Z AS BOUNDARY LAYER SLOWLY COOLS AND
   INSTABILITY DECREASES.
   
   ..MEAD.. 05/18/2007
   
   
   ATTN...WFO...ABR...BIS...UNR...
   
   45840286 46270267 46630241 46790191 46750133 46500081
   46170049 45790034 45410036 44960089 44690154 44590225
   44590274 44680332 44890354