MESOSCALE PRECIPITATION DISCUSSION 0042
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
512 PM EST MON FEB 06 2017
 
AREAS AFFECTED...PORTIONS OF CNTRL TO N-CNTRL CA 
 
CONCERNING...HEAVY RAINFALL 
 
VALID 062207Z - 071007Z
 
SUMMARY...A SURGE IN LOW LEVEL MOISTURE FLUX WILL INCREASE
RAINFALL RATES FOR PORTIONS OF CNTRL TO N-CNTRL CA TONIGHT. THE
HEAVIEST RATES SHOULD FOCUS ALONG THE COASTAL RANGES BUT SOME
FLOODING IMPACTS MAY CONTINUE DOWNSTREAM INTO THE FOOTHILLS OF THE
SIERRA NEVADA. 

DISCUSSION...21Z GOES WEST WATER VAPOR IMAGERY SHOWED A WELL
DEFINED SHORTWAVE TROUGH TRACKING EAST NEAR 37N 144W. AT THE
SURFACE...A COMBINATION OF VISIBLE IMAGERY AND THE AMSU 89 GHZ
CHANNEL REVEALED A T-BONE LIKE STRUCTURE CONTAINING AN ELONGATED
OCCLUDED BOUNDARY WITH A COLD FRONT EXTENDING SWWD FROM AN
ESTIMATED TRIPLE POINT NEAR 38N 135W. SHORT TERM RAP FORECASTS
HAVE ALIGNED WELL WITH THE BLENDED TPW PRODUCT AND THE 1.25 INCH
PRECIPITABLE WATER CONTOUR WITHIN THE WARM SECTOR. PRECIPITABLE
WATER VALUES FARTHER UPSTREAM WITHIN THE MOISTURE PLUME...IN THE
DIRECTION OF HAWAII FOCUSED NEAR 30N 145W...HAVE CONSISTENTLY BEEN
1.5 INCHES TO 2.0 INCHES WITH AMUS AND SSMIS MICROWAVE RAIN RATE
SENSORS INDICATING 0.5 TO 1.0 IN/HR OVER A SOMEWHAT BROAD
RESOLUTION WITH HIGHER RATES LIKELY ON FINER SCALES. 

AS THE SHORTWAVE ADVANCES EAST LATE THIS EVENING...THE WARM FRONT
WILL LIFT NORTH ALLOWING 1.25 INCH PRECIPITABLE WATER VALUES...OR
+3 TO +4 STANDARDIZED ANOMALIES...TO REACH THE CNTRL CA COAST NEAR
06Z ALONG WITH 850 MB WINDS OF 50 KT NEARLY PERPENDICULAR TO THE
COAST INTO THE SANTA CRUZ MOUNTAINS. AFTER 06Z...THE FOCUS FOR
HEAVIER RAIN RATES IN EXCESS OF 0.5 IN/HR WILL SHIFT TO THE
COASTAL RANGES NORTH OF THE BAY AREA. MOISTURE WILL ALSO FUNNEL
INTO THE SRN SACRAMENTO VALLEY WITH STEADY UPSLOPE WINDS INTO THE
N-CNTRL SIERRA NEVADA WITH A FOCUS INTO NEVADA...PLACER AND EL
DORADO COUNTIES WHERE AN ADDITIONAL 3-4 INCHES OF RAIN IS EXPECTED
THROUGH 09Z. RAINFALL RATES ARE GENERALLY FORECAST TO REMAIN
BETWEEN 0.25 AND 0.5 IN/HR AWAY FROM THE COASTAL RANGES...BUT
PERSISTENT RAIN MAY COMPOUND ONGOING FLOODING CONCERNS.

OTTO

ATTN...WFO...EKA...HNX...MTR...STO...

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

LAT...LON   39972340 39372261 38742215 38642157 38852135 
            39952185 39952101 38852023 38271991 38041970 
            37741960 37541951 37271924 37091933 37402010 
            38012063 38212091 38262130 38132158 37932178 
            37742167 37412138 36992159 36832198 37202256 
            37832314 38792380 39602380