MESOSCALE PRECIPITATION DISCUSSION 0078
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1003 AM EST FRI MAR 11 2016
 
AREAS AFFECTED...CENTRAL CA 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 111503Z - 111900Z
 
SUMMARY...THE REMAINING ATMOSPHERIC RIVER MOISTURE AHEAD OF A COLD
FRONT APPROACHING THE CENTRAL COAST COULD RESULT IN HOURLY
RAINFALL RATES IN EXCESS OF 0.50 INCHES. THE ADDITIONAL RAINFALL
COULD RESULT IN A LOCALIZED FLASH FLOOD THREAT.

DISCUSSION...REGIONAL RADARS INDICATED A BLOSSOMING AREA OF
MODERATE TO HEAVY RAINFALL OFF THE CENTRAL CA COAST LINE. THE
ENHANCED RAINFALL IS DUE TO THE NORTHERN EXTENT OF A WEAKENING
ATMOSPHERIC RIVER AHEAD OF A COLD FRONT APPROACHING THE COAST. THE
BLENDED TPW SHOWED PRECIPITABLE WATER VALUES NEAR 1.10 INCHES
(WHICH IS BETWEEN ONE AND TWO STANDARD DEVIATIONS ABOVE THE MEAN)
FEEDING INTO THE AREA OF MODERATE TO HEAVY RAINFALL. THE LATEST
SPC ANALYSIS EVEN SHOWED SOME ELEVATED INSTABILITY (MOSTLY UNDER
300 J/KG). 

HOURLY RAINFALL RATES AS SAMPLED BY KMUX RADAR AND THE LATEST MRMS
PRECIPITATION RATE PRODUCT INDICATED RANGED BETWEEN 0.50 AND 1.00
INCHES...WITH THE HIGHEST RATES SOUTHWEST OF SFO. 

THERE WAS FAIRLY GOOD HIGH RESOLUTION MODEL AGREEMENT WITH THE
THREAT FOR HEAVY RAINFALL TO MOVE INLAND ACROSS PORTIONS OF
CENTRAL CA THROUGH MIDDAY. THE LATEST HRRR/RAP SHOWED THE BEST
THREAT SOUTH OF SFO...BUT BASED ON RADAR TRENDS THIS MAY TOO FAR
SOUTH. THERE WAS ALSO GOOD AGREEMENT ON THE THREAT FOR AS MUCH AS
2.00 INCHES OF RAINFALL THROUGH THAT TIME...MAINLY ON THE
SOUTHWEST FACING SLOPES. THE ADDITIONAL HEAVY RAINFALL WILL RAISE
A THREAT FOR LOCALIZED FLASH FLOODING...AS WELL AS THE THREAT FOR
MUDSLIDES WHERE HEAVY RAINFALL OCCURS EARLIER TODAY.

HAYES

ATTN...WFO...EKA...LOX...MTR...STO...

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

LAT...LON   40112268 39852241 39152226 38342201 36712120 
            35882068 35262057 35312083 36182182 37712271 
            38462322 39342354 39952320