MESOSCALE PRECIPITATION DISCUSSION 0220
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1106 AM EDT SAT AUG 24 2013
 
AREAS AFFECTED...SOUTHEAST CA...EXTREME SOUTHERN NV AND WESTERN AZ 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 241500Z - 241800Z
 
SUMMARY...CLUSTERS OF STRONG CONVECTION WILL CONTINUE TO FOSTER
LOCALLY VERY HVY RAINS OVER THE NEXT FEW HOURS WITH ADDITIONAL
FLASH FLOODING POSSIBLE.

DISCUSSION...IR SAT IMAGERY SHOWS A FAIRLY COMPACT MCS OVER WRN AZ
THAT IS PRODUCING LOCALLY INTENSE RAINFALL RATES. CLOUD TOPS HAVE
GENERALLY CONTINUED TO COOL...AND WV IMAGERY SUGGESTS FAIRLY DIV
FLOW ALOFT OVER THE REGION WHICH IS AIDING IN SOME LARGER SCALE
ASCENT. THE CONVECTION HAS GENERALLY BEEN ADVANCING WWD TOWARD THE
CA/AZ BORDER...AND IS INTERACTING WITH A SHARP INSTABILITY
GRADIENT ORIENTED FROM THE GULF OF CA NORTHWARD INTO SERN CA AND
WRN AZ. GIVEN THE ONSET OF DIURNAL HEATING AND PRESENCE OF AT
LEAST MODEST LARGE SCALE FORCING...THE CURRENT ACTIVITY SHOULD
MAINTAIN ITSELF AND MAY WELL BECOME BETTER ORGANIZED WITH A
FAVORABLE ENVIRONMENT FOR SOME BACK-BUILDING CELLS. THE LARGE
SCALE CONVECTIVE MASS SHOULD TEND TO CONTINUE WWD AND WILL LIKELY
ADVANCE INTO SERN CA OVER THE NEXT COUPLE OF HOURS WITH ADDITIONAL
DEVELOPMENT OVER WRN AND SWRN AZ EXPECTED AS WELL WHERE DEEPER LYR
INSTABILITY IS A BIT STRONGER.

RAINFALL RATES OF 1.5 TO 2 INCHES/HR ARE EXPECTED...AND COULD BE
LOCALLY HIGHER INVOF OF CELL MERGERS. GIVEN THESE RAINFALL
RATES...FLASH FLOODING WILL CONTINUE TO BE POSSIBLE.

ORRISON

ATTN...WFO...FGZ...PSR...VEF...

ATTN...RFC...CBRFC...CNRFC...

LAT...LON   32641444 33101511 33931541 34941541 35871517 36141407
            35311335 34941173 33901134 32991215 32521320 32641444