MESOSCALE DISCUSSION 1645
   NWS STORM PREDICTION CENTER NORMAN OK
   0752 PM CDT TUE JUL 21 2009
   
   AREAS AFFECTED...CNTRL AZ
   
   CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 
   
   VALID 220052Z - 220215Z
   
   FAIRLY VIGOROUS STORMS GENERATING COLD OUTFLOW APPEAR TO BE IN THE
   PROCESS OF DEVELOPING OFF THE MOGOLLON RIM TOWARD THE LOWER DESERTS
   OF CENTRAL ARIZONA...INCLUDING THE PHOENIX METROPOLITAN AREA. 
   DURING THE NEXT FEW HOURS...THIS APPEARS LIKELY TO BE AIDED BY 20 KT
   NORTHWESTERLY LOWER/MID TROPOSPHERIC FLOW TO THE SOUTH OF A WEAK
   UPPER TROUGH EMBEDDED WITHIN THE LARGER SCALE INTERMOUNTAIN WEST
   RIDGE.  THE RELATIVELY MOIST ENVIRONMENT IN AND AROUND PHOENIX HAS
   BECOME VERY WARM WITH TEMPERATURES NOW ABOVE 100F...AND APPEARS
   CHARACTERIZED BY SUFFICIENT INSTABILITY TO SUPPORT RENEWED STORM
   DEVELOPMENT ALONG ADVANCING OUTFLOWS BY THE 02-03Z TIME FRAME.  SOME
   HAIL AND LOCALLY HEAVY RAINFALL IS POSSIBLE...BUT THE RISK FOR
   DAMAGING DOWNBURSTS ASSOCIATED WITH LARGE SUB-CLOUD TEMPERATURE 
   /DEW POINT SPREADS SEEMS TO BE THE PRIMARY CONVECTIVE HAZARD BEFORE
   STORMS DIMINISH LATER THIS EVENING.
   
   ..KERR.. 07/22/2009
   
   
   ATTN...WFO...TWC...PSR...
   
   LAT...LON   33831244 33691173 33541132 33111072 32981215 33641260
               33831244