MESOSCALE PRECIPITATION DISCUSSION 6
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
336 AM EST SAT JAN 7 2017
 
AREAS AFFECTED...CENTRAL CALIFORNIA 
 
CONCERNING...HEAVY RAINFALL 
 
VALID 070834Z - 072034Z
 
SUMMARY...A LONG DURATION HEAVY PRECIPITATION EVENT WITH LOWER
ELEVATION HEAVY RAINFALL IS EXPECTED TO COMMENCE ACROSS CENTRAL
CALIFORNIA DURING THE DAY SATURDAY.  THIS IS JUST THE BEGINNING OF
WHAT WILL LIKELY BE A TWO-DAY EVENT WITH RAINFALL AMOUNTS HIGHER
THAN WHAT WAS OBSERVED A FEW DAYS AGO.

DISCUSSION...A DEEP SURGE OF PACIFIC MOISTURE IS ADVECTING TOWARDS
THE CENTRAL CALIFORNIA WITH A SUBTROPICAL CONNECTION.  PW
STANDARDIZED ANOMALIES ON THE ORDER OF +3 ARE INDICATED BY THE
GEFS MEAN, WITH 1.5 INCH PWS SUGGESTED BY THE LATEST RAP GUIDANCE
TO REACH THE CENTRAL CALIFORNIA COAST BY 20Z SATURDAY.   A
PROLONGED FETCH OF 40 TO 50 KNOT 850MB FLOW ORIENTED ORTHOGONAL TO
THE TERRAIN, ALONG WITH THE ANOMALOUS PWS, IS SETTING THE STAGE
FOR ENHANCED RAINFALL BY SATURDAY AFTERNOON.  THE HEAVIEST
RAINFALL TOTALS ARE EXPECTED FOR THE COASTAL MOUNTAINS SOUTH OF
SAN FRANCISCO, AND THE WESTERN SLOPES OF THE CENTRAL SIERRA NEVADA
BELOW 7000 FEET.  

THE LATEST HI-RES GUIDANCE IS INDICATING 1 TO LOCALLY 2 INCHES OF
RAINFALL BY 20Z, WITH MUCH MORE AFTER THIS TIME.  RAINFALL RATES
ON THE ORDER OF 0.3 INCH PER HOUR ARE LIKELY WITH THE ADDED
OROGRAPHIC FORCING.  THE PLACES WITH GREATEST RUN-OFF CONCERNS
WOULD BE RECENT BURN-SCAR AREAS AND THOSE LOCATIONS THAT RECEIVED
APPRECIABLE RAINFALL EARLIER IN THE WEEK.  


HAMRICK

ATTN...WFO...HNX...LOX...MTR...STO...

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

LAT...LON   39702117 39572094 39242076 38412037 37922010 
            37591970 37301933 36691887 36321869 35721858 
            35241854 34891875 34581916 34332001 34502072 
            35182094 35802163 36382202 37112252 37672264 
            37962215 37832169 37322121 36902072 37002018 
            37482026 38002074 38502109 39122136 39572140 
            
a