MESOSCALE DISCUSSION 1487
   NWS STORM PREDICTION CENTER NORMAN OK
   0340 PM CDT SUN JUL 03 2011
   
   AREAS AFFECTED...CNTRL/SCNTRL AZ
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 032040Z - 032315Z
   
   STRONG TO POSSIBLY SEVERE THUNDERSTORMS WILL IMPACT CNTRL/SCNTRL AZ
   THROUGH MID-EVENING...INCLUDING THE GREATER PHX AREA.  A SEVERE
   THUNDERSTORM WATCH IS POSSIBLE...ROUGHLY 50 PERCENT PROBABILITY. 
   PRIMARY IMPACTS WILL BE DAMAGING MACROBURST WINDS.
   
   BOUNDARY LAYER MOISTURE INCREASE...OWING TO BOTH OUTFLOW FROM
   YESTERDAY/S SONORA MCS AND AN EARLY MORNING GULF OF CA SURGE...HAS
   RESULTED IN A RESERVOIR OF MLCAPES OF 1000-1500 J/KG FROM KTUS-KPHX
   W INTO THE LWR DESERTS.  WHILE SOME MIXING/DRYING WILL LIKELY OCCUR
   /PARTICULARLY KTUS EWD/...EXPECT THAT CONSIDERABLE CAPE WILL BE
   AVAILABLE THROUGH EVENING.
   
   TAIL-END OF A MID-LEVEL WAVE APPEARS TO BE MOVING ACROSS NRN SONORA
   AND SERN AZ AT 19Z AND THIS WILL LIKELY MAINTAIN A FAVORABLE UPPER
   LEVEL DIVERGENT PATTERN OVER CNTRL/SCNTRL AZ THROUGH PEAK HEATING. 
   STORMS HAVE ALREADY FORMED OVER THE RIM COUNTRY EARLY THIS AFTN AND
   HIGH-BASED STORMS MAY ALSO DEVELOP OVER THE HIGHER TERRAIN OF
   SCNTRL/SERN AZ WITH TIME.  THESE STORMS MAY PRODUCE GUSTY WINDS.
   
   CONCERN IS THAT AS OUTFLOW BOUNDARIES CONSOLIDATE AND MOVE
   WWD...STORMS WILL EASILY INITIATE ACROSS THE LOWER DESERTS BY LATE
   AFTN/EARLY EVENING.  HERE...INSOLATION WILL BE AT A PREMIUM AS
   EARLIER HIGH-ELEVATION STORM DEBRIS REMAINS CLEAR OF THE DESERTS. 
   NUMEROUS CONVECTION-ALLOWING MODELS SUGGEST AN UPTICK IN STORM
   DEVELOPMENT AFTER 00Z OVER THE GREATER PHX AREA AND POINTS WSW AND
   THIS SEEMS REASONABLE.
   
   UPSLOPE FLOW HAS WEAKENED IN THE PHX AREA RECENTLY...WITH A
   DOWNSLOPE FLOW AT KTUS.  WHILE THIS WILL REDUCE OVERALL SHEAR...IT
   WILL BE SUFFICIENT FOR ORGANIZED STORMS...PRIMARILY LINEAR...WWD
   PROPAGATING MODES GIVING SCATTERED MACROBURSTS.  SVR THREAT WILL
   PROBABLY PERSIST WELL INTO THE EVENING OVER SWRN AZ WITH A CONTINUED
   WIND THREAT.
   
   ..RACY.. 07/03/2011
   
   
   ATTN...WFO...TWC...FGZ...PSR...VEF...
   
   LAT...LON   32381437 33621436 34641391 35111219 34841142 34090961
               33441043 33161088 32111093 31351112 31581188 32381437