MESOSCALE DISCUSSION 0621
   NWS STORM PREDICTION CENTER NORMAN OK
   0843 AM CDT FRI MAY 10 2013
   
   AREAS AFFECTED...MIDDLE AND UPPER TX COASTAL PLAIN
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 101343Z - 101415Z
   
   PROBABILITY OF WATCH ISSUANCE...60 PERCENT
   
   SUMMARY...ISOLD LARGE HAIL POTENTIAL MAY AFFECT THE MIDDLE AND UPPER
   TX COASTAL PLAIN.  A SEVERE WATCH DECISION WILL LIKELY NEED TO BE
   MADE BY 14Z OR SO.
   
   DISCUSSION...RADAR MOSAIC SHOWS A DIFFUSE CLUSTER OF EWD MOVING
   STORMS FROM 20 MI E SAT TO 20 MI WSW UTS.  AN OUTFLOW BOUNDARY
   EXTENDS FROM THE TRAILING EDGE OF THE LA MCS WWD TOWARDS THE STORM
   OVER WILSON COUNTY.  THE STORMS ALONG AND N OF THE BOUNDARY ARE
   LIKELY ROOTED AT THE TOP OF THE BOUNDARY-LAYER ON THE NERN PERIPHERY
   OF AN UNCONVECTIVELY-MODIFIED EML PLUME OF VERY STEEP LAPSE RATES
   SAMPLED BY THE 12Z CRP RAOB.  ADEQUATE MID LEVEL FLOW /40 KT AT KEWX
   AND KHGX AT 6 KM AGL/ WILL ACT TO SUPPORT UPDRAFT ORGANIZATION.  AS
   SUCH...A LARGE HAIL THREAT MAY DEVELOP/INCREASE AS THE STORMS MOVE
   EWD AND IMPACT THE MIDDLE TO UPPER TX COASTAL PLAIN THROUGH THE
   MORNING HOURS.
   
   ..SMITH/CARBIN.. 05/10/2013
   
   
   ATTN...WFO...HGX...CRP...EWX...
   
   LAT...LON   29229820 29739733 29779633 29319484 28869541 28529622
               28709771 29229820