MESOSCALE DISCUSSION 0506
   NWS STORM PREDICTION CENTER NORMAN OK
   0323 PM CDT THU APR 21 2011
   
   AREAS AFFECTED...N-CNTRL AND NERN TX
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 212023Z - 212130Z
   
   N-CNTRL AND NERN TX ARE BEING MONITORED FOR CONVECTIVE INITIATION
   OVER THE NEXT FEW HOURS.  CONTINGENT UPON STORMS DEVELOPING AND
   MATURING...AN ISOLD TORNADO THREAT MAY DEVELOP...IN ADDITION TO
   LARGE TO VERY LARGE HAIL AND DMGG WINDS.  A WW IS POSSIBLE.
   
   VISIBLE SATELLITE/SURFACE OBSERVATIONS SHOW A RETREATING WARM FRONT
   SLOW LIFTING NWD ACROSS THE N-CNTRL AND NERN TX AREA THIS AFTERNOON.
   TEMPS S OF THE WARM FRONT/LOW CLOUDS HAVE WARMED WELL INTO THE 80S
   CONTRIBUTING TO WEAKENING CINH.  A MOIST BOUNDARY LAYER /PW VALUES
   EXCEEDING 1.6 INCH/ BENEATH STEEP LAPSE RATES/EML PLUME ARE
   CONTRIBUTING TO A VERY UNSTABLE AIRMASS ALONG AND S OF THE WARM
   FRONT.  SURFACE STREAMLINE ANALYSIS INDICATES THAT ONLY TEMPERED LOW
   LEVEL CONVERGENCE IS OCCURRING ALONG THE RETREATING BOUNDARY. 
   UNCERTAINTY EXISTS WHETHER OR NOT HEATING ALONE MAY INITIATE STORMS
   IN THE NEXT FEW HOURS AS THE BULK OF WAA/ISENTROPIC LIFT REMAINS
   FOCUSED FARTHER N ACROSS ERN OK/WRN AR.
   
   WITH THOSE CONCERNS STATED...A VEERING LOW LEVEL WIND PROFILE WITH
   INCREASING FLOW WITH HEIGHT WOULD BE FAVORABLE FOR SUPERCELLS AND A
   CONDITIONAL ISOLD TORNADO RISK.  VISIBLE SATELLITE/RADAR TRENDS WILL
   CONTINUE TO BE MONITORED OVER THE NEXT FEW HOURS TO ADDRESS THE NEED
   FOR A POSSIBLE WW.
   
   ..SMITH.. 04/21/2011
   
   
   ATTN...WFO...SHV...FWD...OUN...
   
   LAT...LON   32249487 32159727 32469846 33349847 33739810 33569557
               33309456 32739440 32249487