MESOSCALE DISCUSSION 2172
   NWS STORM PREDICTION CENTER NORMAN OK
   0229 PM CDT TUE SEP 13 2011
   
   AREAS AFFECTED...LOWER CO RIVER VALLEY AND GILA RIVER VALLEY
   
   CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 
   
   VALID 131929Z - 132030Z
   
   THE THREAT FOR A FEW STORMS CAPABLE OF LARGE HAIL/DMGG WIND GUST MAY
   INCREASE INVOF THE CONFLUENCE OF THE GILA AND COLORADO RIVERS IN FAR
   SWRN AZ AND FAR SERN CA NEAR THE MEXICAN BORDER.  
   
   RECENT KYUX RADAR TRENDS HAVE SHOWN A FEW DEVELOPING STORMS
   ACQUIRING MIDLEVEL ROTATION S OF THE BORDER NEAR NRN TIP OF THE GULF
   OF CALIFORNIA.  CONVECTIVE OUTFLOW EMANATING FROM ONGOING CONVECTIVE
   CLUSTER OVER RIVERSIDE COUNTY CA WILL LIKELY ACT TO LIMIT THE AREAL
   NWD EXTENT OF MODERATE INSTABILITY TO BE S OF THE BORDER.  THE 18Z
   1Y7 /YUMA/ RAOB FEATURES STEEP LAPSE RATES AND MOIST MID-LEVELS WITH
   35 KTS H5 FLOW--SUPPORTIVE OF SOME STORM ORGANIZATION.  WITH THE
   UPPER LOW/VORT MAX LOCATED TO THE W ONLY EXPECTED TO MAKE GRADUAL
   EWD PROGRESS DURING THE NEXT FEW HOURS...THIS REGION WILL REMAIN
   WITHIN A BELT OF STRONGER DEEP LAYER SHEAR AND FORCING FOR ASCENT ON
   THE ERN SIDE OF THE UPPER LOW...AND ACT TO PROMOTE A MODEST SEVERE
   RISK THROUGH THE AFTERNOON HOURS.
   
   ..SMITH.. 09/13/2011
   
   
   ATTN...WFO...PSR...
   
   LAT...LON   32631499 32951475 32981422 32691349 32111334 31981350
               32381487 32631499