MESOSCALE DISCUSSION 0787
   NWS STORM PREDICTION CENTER NORMAN OK
   1202 AM CDT SUN MAY 10 2009
   
   AREAS AFFECTED...PARTS OF NRN TX/SRN OK INTO THE ARKLATEX
   
   CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 
   
   VALID 100502Z - 100700Z
   
   POTENTIAL FOR HEAVY RAINFALL MAY INCREASE OVERNIGHT.  THE RISK FOR
   SEVERE STORMS SEEMS RELATIVELY LOW/MARGINAL...BUT TRENDS WILL BE
   MONITORED.
   
   AS THE NEXT BROAD...LOW AMPLITUDE IMPULSE DIGS ACROSS THE GREAT
   BASIN AND CENTRAL ROCKIES...AN INCREASE IN CONVECTIVE DEVELOPMENT
   APPEARS TO BE UNDERWAY ACROSS THE REGION.  THIS IS OCCURRING
   GENERALLY WITHIN A ZONE OF STEEPER ISENTROPIC ASCENT NORTH OF A
   STALLED SURFACE FRONT...WHERE LAPSE RATES REMAIN RELATIVELY
   STEEP...AND MOISTURE CONTENT IS CHARACTERIZED BY PRECIPITABLE WATER
   OF 1.5 TO 1.75+ INCHES.  MIXED LAYER CAPE ON THE ORDER OF 1000-2000
   J/KG IS SUPPORTIVE OF VIGOROUS UPDRAFTS...BUT A CAPPING ELEVATED
   MIXED LAYER HAS SLOWED STORM DEVELOPMENT WEST OF THE ARKLATEX.  
   
   SUSTAINED LIFT MAY CONTINUE TO WEAKEN INHIBITION NEAR THE RED RIVER
   VALLEY DURING THE NEXT FEW HOURS...ALLOWING FOR A GRADUAL
   INTENSIFICATION OF CONVECTION.  GIVEN WEAK BUT VEERING WIND PROFILES
   WITHIN THE INFLOW LAYER...BENEATH MODEST WESTERLY 500 MB FLOW ON THE
   ORDER OF 30 KTS...MID-LEVEL UPDRAFT ROTATION MAY CONTRIBUTE TO THE
   RISK FOR AT LEAST MARGINALLY SEVERE HAIL IN STRONGEST CELLS.  
   
   IT IS POSSIBLE THAT A MID-LEVEL SPEED MAXIMUM COULD ENHANCE
   MID/UPPER FORCING FOR UPWARD VERTICAL MOTION ACROSS THE REGION...ON
   THE SOUTHERN FRINGE OF THE STRONGER WESTERLIES TOWARD THE 07-09Z
   TIME FRAME.  IF THIS OCCURS...AN EVOLVING STORM CLUSTER WITH
   TRAINING CELLS MAY EVENTUALLY CONTRIBUTE TO THE RISK FOR EXCESSIVE
   RAIN TOTALS IN THE PRESENCE OF THE HIGH MOISTURE CONTENT.
   
   ..KERR.. 05/10/2009
   
   
   ATTN...WFO...LZK...SHV...TSA...FWD...OUN...
   
   LAT...LON   33919724 34309635 34169394 33749301 33359257 32809328
               32649394 32759473 32949594 32899685 32849719 33489768
               33919724