MESOSCALE PRECIPITATION DISCUSSION 0014
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
214 PM EST TUE JAN 10 2017
 
AREAS AFFECTED...CNTRL/NRN CA COAST INTO SIERRA NEVADA RANGE 
 
CONCERNING...HEAVY RAINFALL 
 
VALID 101912Z - 110600Z
 
SUMMARY...A RENEWED SURGE IN LOW LEVEL MOISTURE FLUX INTO
NRN/CNTRL CA LATER THIS AFTERNOON WILL INCREASE RAINFALL RATES
ABOVE 0.5 IN/HR ALONG THE COASTAL RANGES AND INTO THE SIERRA
NEVADA. THE POTENTIAL FOR RAINFALL RATES TO ECLIPSE 0.75 IN/HR
WILL EXIST FARTHER SOUTH ALONG THE COASTAL RANGES FROM NEAR SAN
FRANCISCO BAY TO THE SANTA LUCIA RANGE AFTER 00Z.

DISCUSSION...19Z WATER VAPOR IMAGERY SHOWED A PROGRESSIVE CLOSED
LOW/UPPER TROUGH ADVANCING EAST NEAR 130W OFF OF THE OR/CA
COAST...WITH A PLUME OF MID-UPPER LEVEL MOISTURE STREAMING NEWD
INTO MUCH OF OR/NRN CA. BLENDED TPW IMAGERY AND RECENT RUNS OF THE
RAP INDICATE THAT PRECIPITABLE WATER VALUES WITHIN THE PLUME WERE
GENERALLY 1.0 TO 1.2 INCHES. AT THE SURFACE...A DEVELOPING SURFACE
LOW WAS ANALYZED NEAR 42N 127W WITH AN OCCLUDED/COLD FRONT
EXTENDING SWWD THROUGH THE ERN PACIFIC. GOES HD WINDS INDICATED
THAT THE LEFT EXIT REGION OF A 130-150 KT JET STREAK NEAR 250 MB
WAS APPROACHING NWRN CA AT 19Z...WITH THIS REGION OF ENHANCED LIFT
EXPECTED TO STEADILY DROP SOUTH AND EAST ACROSS CA OVER THE NEXT
6-12 HOURS. 

INCREASING FREEZING LEVELS WILL FOLLOW THE APPROACH OF THE COLD
FRONT...LIKELY RAISING SNOW LEVELS IN THE CNTRL/NRN SIERRA NEVADA
INTO THE 7000-8000 FT RANGE FOR 6-9 HOURS AFTER 00Z. THIS WARM UP
WILL ACCOMPANY THE INCREASED SURGE IN LOW LEVEL MOISTURE FLUX AND
RAINFALL RATES IN EXCESS OF 0.5 IN/HR. ONGOING RAINFALL RATES OF
0.5 IN/HR AND HIGHER ALONG THE NWRN CA COAST WILL STEADY DROP
SOUTH ALONG THE CA COAST THIS EVENING WITH A SUBTLE INCREASE IN
850 MB WIND SPEEDS EXPECTED NEAR 06Z. 55-60 KTS OF FLOW ARE
EXPECTED INTO THE COASTAL RANGES NEAR AND SOUTH OF SFO...INCLUDING
THE SANTA CRUZ MOUNTAINS AND SANTA LUCIA RANGE WHERE RAIN RATES IN
EXCESS OF 0.75 IN/HR WILL BE POSSIBLE. THESE HIGHER RAIN RATES
ALONG WITH BURN SCAR LOCATIONS AND SATURATED SOILS MAY LEAD TO
LOCALIZED FLASH FLOODING. 12 HOUR RAINFALL TOTALS ENDING 07Z ARE
EXPECTED TO RANGE FROM 3-4 INCHES FOR THE NRN AND CNTRL CA COASTAL
RANGES INTO THE CNTRL/NRN SIERRA NEVADA...WITH LOCALLY HIGHER
TOTALS POSSIBLE WITH SOME HI-RES MODEL OUTPUT AS HIGH AS 6 INCHES
INTO THE SIERRA NEVADA.

OTTO

ATTN...WFO...EKA...HNX...LOX...MFR...MTR...REV...STO...

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

LAT...LON   42462399 42392357 42002320 41522274 41452183 
            41012152 40042063 39552003 38691980 38641984 
            38251967 37941949 37671939 37481911 37271897 
            37011891 36841907 36861934 36961957 37422038 
            37632075 37112104 36182048 35412090 35842164 
            36472226 37712301 39062385 40652405 42162425