MESOSCALE PRECIPITATION DISCUSSION 0030
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
531 PM EST FRI JAN 20 2017
 
AREAS AFFECTED...SRN CA 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 202230Z - 210330Z
 
SUMMARY...FLASH FLOODING REMAINS A THREAT INTO THE SRN COASTAL
RANGES OF CA FOR THE NEXT FEW HOURS WITH RAINFALL RATES EXCEEDING
1 IN/HR AT TIMES. 

DISCUSSION...RAINFALL RATES AHEAD OF A COLD FRONT HAVE BEEN IN
EXCESS OF 1 IN/HR DURING THE DAY TODAY WITHIN A CORRIDOR OF STRONG
LOW LEVEL FLOW AHEAD OF A PROGRESSIVE COLD FRONT. 60 KTS OF FLOW
HAS BEEN OBSERVED VIA THE KNKX VAD WIND PROFILE ABOVE 4000 FT AGL.
DESPITE PRECIPITABLE WATER VALUES VIA GPS SITES HAVE BEEN HOVERING
NEAR 1 INCH AS OF 21Z FROM THE COAST OF VENTURA TO ORANGE
COUNTIES. THE LEFT EXIT REGION OF A POWERFUL MID-UPPER LEVEL JET
CORE CONTINUES TO PROVIDE ENHANCEMENT TO LIFT ACROSS THE REGION.

THE COLD FRONT HAS BEEN RAPIDLY DROPPING DOWN THE COAST AT ROUGHLY
40 KTS...AND WAS NEAR LAX AT 22Z. RAINFALL RATES IN EXCESS OF 1
IN/HR WILL CONTINUE TO BE POSSIBLE ACROSS SRN CA BEFORE THE COLD
FRONT PASSES THROUGH THE REGION. THE BEST MOISTURE WILL RAPIDLY
DROP SOUTH OF THE U.S. BORDER INTO BAJA AFTER 00Z BUT 850 MB WINDS
OF NEARLY 50 KTS WILL CONTINUE TO AIM NEARLY PERPENDICULAR INTO
THE PENINSULA RANGES OF SRN CA WITH STEEPENING LOW LEVEL LAPSE
RATES WHICH MAY SUPPORT LOCALIZED AREAS OF RAINFALL RATES IN
EXCESS OF 0.50 IN/HR AFTER THE FRONT MOVES THROUGH. 6 HR RAINFALL
OF 1.5 TO 2.5 INCHES WILL BE POSSIBLE INTO UPSLOPE FAVORED
TERRAIN. 

OTTO

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

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

LAT...LON   34551821 34521733 34251659 33721643 33501630 
            33051616 32561587 32451715 33111752 33661820 
            34361858