MESOSCALE PRECIPITATION DISCUSSION 0353
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1029 AM EDT MON SEP 08 2014
 
AREAS AFFECTED......ARIZONA/S. CALIFORNIA... 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 081429Z - 081829Z
 
SUMMARY...FLASH FLOODING REMAINS LIKELY THROUGH 18Z DUE TO A
COMBINATION OF HIGHLY ANOMALOUS MOISTURE/INSTABILITY AND LIGHT
STEERING FLOW SURROUNDING AN MCV NEAR PHOENIX.

DISCUSSION...KIWA AND KEMX RADARS SHOW A NEARLY STEADY STATE MCV
WEST OF PHOENIX WHICH IS LIKELY DELAYING THE DIURNAL WEAKENING OF
THE LOW LEVEL JET...WHICH IS ASCENDING AN UNUSUALLY STRONG AND
DEEP COLD POOL WHICH HAS STALLED SOUTH OF PHOENIX. 
ADDITIONALLY...RADAR AND EARLY MORNING VISIBLE SATELLITE SHOW
CONVECTION CONTINUING TO REDEVELOP NORTH OF THE OUTFLOW IN
VICINITY OF THE LOWER ELEVATIONS OF THE MOGOLLON RIM AS WELL AS
THE SAN BERNARDINOS AND JUST SOUTH OF MOUNT CHARLESTON IN SOUTHERN
NEVADA.  

RECENT HRRR AND RAP DATA SEEM TO CAPTURE SOME ASPECTS OF THE
CURRENT CONVECTION ACTIVITY...PARTICULARLY THE MCV...WHICH
GUIDANCE ALLOWS TO DRIFT NORTH NORTHWESTWARD BY 18Z.  GIVEN THESE
CONDITIONS...EXPECT THE CURRENT CONVECTIVE ACTIVITY AND ASSOCIATED
HEAVY RAINFALL TO CONTINUE THROUGH ABOUT 18Z BEFORE CONSOLIDATING
SLIGHTLY AND LIFTING NORTHWARD.  EXPECT RAIN RATES OF 0.5 TO
PERHAPS 1.5 INCHES PER HOUR TO CONTINUE...WHICH MAY WORSEN
EXISTING FLOODING CONDITIONS OR CONTRIBUTE TO NEW AREAS OF FLASH
FLOODING.

JAMES

ATTN...WFO...FGZ...PSR...SGX...TWC...VEF...

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

LAT...LON   35771432 34971209 33741074 32821100 33081272 
            34611416 34581564 33361589 33041651 34311689 
            35521616