MESOSCALE PRECIPITATION DISCUSSION 0578
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1013 AM EDT FRI OCT 16 2015
 
AREAS AFFECTED...SOUTHEAST CA...SOUTHERN NV...NW ARIZONA 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 161410Z - 161810Z
 
SUMMARY...ADDITIONAL SHOWERS AND THUNDERSTORMS WITH LOCALLY HEAVY
RAINFALL RATES ARE LIKELY TO CONTINUE OVER THIS REGION OVER THE
NEXT FEW HOURS.  GIVEN WET GROUND FROM EARLIER RAINFALL FROM THE
SAME STORM SYSTEM...FLASH FLOODING AND RUN-OFF WILL REMAIN
POSSIBLE ON A LOCALIZED SCALE.

DISCUSSION...THE LATEST SATELLITE IMAGERY SHOWS A WELL-DEFINED
UPPER LOW MOVING GRADUALLY NORTH INTO CENTRAL PORTIONS OF
CALIFORNIA...AND THIS CONTINUES TO INTERACT WITH AN ANOMALOUSLY
MOIST AIRMASS FOR LOCALLY HEAVY SHOWERS AND THUNDERSTORMS.  MUCAPE
VALUES REMAIN ON THE LOW SIDE WITH VALUES AT OR BELOW 500 J/KG AND
THIS WILL HELP KEEP RAINFALL RATES FROM GETTING EXTREME.  THE MAIN
THING HELPING TO SUSTAIN CONVECTION HERE IS SUFFICIENT LARGE SCALE
ASCENT FROM UPPER LEVEL DIFFLUENCE ASSOCIATED WITH THE UPPER LOW.

IN TERMS OF PRECIPITABLE WATER...VALUES HAVE BEEN ON THE ORDER OF
1.25 TO 1.50 INCHES AND THIS IS ABOUT 3 TO 4 STANDARD DEVIATIONS
ABOVE NORMAL.  SOME CONVECTIVE CELLS OVER SOUTHEAST CALIFORNIA
HAVE TENDED TO REPEAT OVER THE SAME AREA GIVEN RATHER
UNIDIRECTIONAL DEEP LAYER FLOW OVER THE REGION.  NEAR TERM HI-RES
MODEL GUIDANCE IS GENERALLY MODEST WITH THEIR QPF AMOUNTS OVER THE
NEXT FEW HOURS, WITH ISOLATED ONE INCH AMOUNTS POSSIBLE THROUGH
18Z WITH THE HEAVIEST CONVECTION.  THIS IS A MARGINAL EVENT FOR
FLASH FLOODING AND SHOULD BE LOCALIZED IF IT OCCURS.  


HAMRICK

ATTN...WFO...PSR...SGX...VEF...

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

LAT...LON   37521742 37521601 36521444 35271378 34191400 
            34001531 34191664 35351740 36811790