MESOSCALE DISCUSSION 0623
   NWS STORM PREDICTION CENTER NORMAN OK
   0133 PM CDT FRI MAY 10 2013
   
   AREAS AFFECTED...MIDDLE RIO GRANDE VALLEY
   
   CONCERNING...SEVERE POTENTIAL...WATCH LIKELY 
   
   VALID 101833Z - 101930Z
   
   PROBABILITY OF WATCH ISSUANCE...95 PERCENT
   
   SUMMARY...SCTD STRONG TO SEVERE STORMS WILL DEVELOP THIS AFTERNOON
   OVER THE MIDDLE RIO GRANDE VALLEY AND POSE A LARGE HAIL AND DMGG
   WIND RISK WITH THE MORE ROBUST STORMS.  AN ATTENDANT VERY LARGE HAIL
   THREAT MAY MATERIALIZE WITH THE MORE INTENSE SUPERCELLS.
   
   DISCUSSION...SURFACE ANALYSIS PLACES A DECELERATING COLD FRONT FROM
   THE TX BIG BEND EWD THROUGH THE TX HILL COUNTRY WITH AN OUTFLOW
   BOUNDARY ARCING WNWWD FROM 30 MI S SAT TO 20 MI S 6R6.  THESE
   BOUNDARIES AND THE HIGHER TERRAIN OVER THE TX BIG BEND AND NRN
   COAHUILA WILL SERVE AS FOCI FOR STORM DEVELOPMENT OVER THE NEXT
   SEVERAL HOURS AS THE CAP IS EFFECTIVELY REMOVED...AND AS THE
   BOUNDARY LAYER CONTINUES TO HEAT/DESTABILIZE AHEAD OF A BAJA CA
   UPPER TROUGH.  THE ELY COMPONENT TO THE LOW LEVEL FLOW HAS LED TO
   LOWER 50S DEWPOINTS MOVING INTO THE AREA SURROUNDING THE HIGHER
   TERRAIN AND CONTRIBUTED TO A MODERATELY UNSTABLE AIRMASS /1000-2500
   J/KG MLCAPE/.  STRONG WSWLY FLOW IN THE MID-HIGH LEVELS IS YIELDING
   50-60 KT EFFECTIVE SHEAR AND WILL AID IN UPDRAFT
   ORGANIZATION/PERSISTENCE...INCLUDING SUPERCELLS.  THE MAIN THREATS
   WITH THESE STORMS WILL BE LARGE HAIL AND DMGG WINDS.  AN ISOLD VERY
   LARGE HAIL THREAT /2 INCHES OR GREATER IN DIAMETER/ IS POSSIBLE WITH
   ANY INTENSE SUPERCELL...ALONG WITH A CONDITIONAL NON-ZERO TORNADO
   THREAT GIVEN BACKED LOW LEVEL FLOW.
   
   ..SMITH/CARBIN.. 05/10/2013
   
   
   ATTN...WFO...EWX...SJT...MAF...
   
   LAT...LON   29850413 30420227 30359983 29469930 28320002 29200395
               29850413