MESOSCALE PRECIPITATION DISCUSSION 0771
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
342 AM EST SAT NOV 19 2016
 
AREAS AFFECTED...NRN CA 
 
CONCERNING...HEAVY RAINFALL 
 
VALID 190841Z - 192041Z
 
SUMMARY...HEAVY RAIN IS EXPECTED TO FOCUS ACROSS THE N-CNTRL
COASTAL RANGES IN THE NEAR TERM BEFORE MOVING INTO THE NRN
SACRAMENTO VALLEY AND FOOTHILLS OF THE NRN SIERRA NEVADA THROUGH
18Z. RAINFALL RATES OF 0.5-0.8 IN/HR WILL BE POSSIBLE WITH 12 HR
RAINFALL OF 3-4 INCHES WITHIN THE MAXIMA.

DISCUSSION...SURFACE OBSERVATIONS AS OF 08Z AND INFRARED SATELLITE
IMAGERY SUGGESTED A PACIFIC COLD FRONT HAD MADE LANDFALL ACROSS
CAPE MENDOCINO IN NRN CA. 850 MB WINDS...VIA THE KBHX VAD WIND
PROFILE...PEAKED NEAR 70 KT AROUND 06Z JUST AHEAD OF THE COLD
FRONT...SLIGHTLY HIGHER THAN RECENT RAP FORECASTS. BLENDED TPW
IMAGERY SHOWED AN ELONGATED AXIS OF PRECIPITABLE WATER VALUES OVER
1 INCH ALONG AND AHEAD OF THE FRONT WITH GPS SITES MEASURING 1.0
TO 1.2 INCHES ALONG THE COAST BETWEEN FORT BRAGG AND POINT REYES.
IN ADDITION...RAP MODEL ANALYSES AND SHORT TERM FORECASTS FROM THE
NAM AND GFS SUPPORTED A 130 KT JET MAX ACROSS THE WRN CA/OR
BORDER...WITH COOLING CLOUD TOPS NOTED OVER SISKIYOU AND TRINITY
COUNTIES.

AT 08Z...THE HEAVIEST RAINFALL RATES WERE LIKELY CONFINED TO NWRN
CA WITH UPSLOPE ENHANCEMENT ACROSS TRINITY AND SISKIYOU COUNTIES
ALONG WITH RIGHT ENTRANCE REGION DIVERGENCE FROM THE
AFOREMENTIONED SPEED MAX. HOWEVER...AS THE COLD FRONT CONTINUES TO
MOVE INLAND THIS MORNING...THE GREATEST LOW LEVEL MOISTURE FLUX
WILL IMPACT THE COASTAL RANGES DOWN TO JUST NORTH OF SAN FRANCISCO
BAY THROUGH 18Z. IT IS HERE THAT HOURLY RAINFALL RATES OF 0.5 TO
0.6 IN/HR ARE EXPECTED THROUGH 12Z/13Z. MOISTURE WILL BEGIN TO
FUNNEL INTO THE NRN SACRAMENTO VALLEY THROUGH 12Z...RAP FORECASTS
SHOWING 1.1 TO 1.2 INCHES AND A 6-9 HR LONG PERIOD OF ENHANCED
1000-700 MB MOISTURE FLUX CONVERGENCE FROM JUST NORTH OF THE SAN
FRANCISCO BAY AREA INTO THE NRN SACRAMENTO VALLEY...WITH UPSLOPE
INTO THE SRN CASCADES/NRN SIERRA NEVADA MOUNTAINS. FREEZING LEVELS
ARE FORECAST TO RISE AS THIS OCCURS TO ROUGHLY 6000-7000 FT AT THE
FOOTHILLS WHERE 12Z-18Z RAINFALL RATES ARE EXPECTED TO EXCEED 0.5
IN/HR AT TIMES WITH LOCALLY 3-4 INCH TOTALS THROUGH 21Z. 

OTTO

ATTN...WFO...EKA...MFR...MTR...STO...

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

LAT...LON   41252259 41192213 40812187 40382166 40022147 
            39692112 39222095 38802133 37932222 37522292 
            37992354 38782398 40112379 41022330