Area Forecast Discussion
Issued by NWS San Francisco Bay Area, CA

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000
FXUS66 KMTR 180002
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
402 PM PST WED DEC 17 2014

.SYNOPSIS...SHOWERS WILL LINGER OVER THE REGION THROUGH TONIGHT
BEFORE A BRIEF LULL IN PRECIPITATION ON THURSDAY. OUR NEXT SYSTEM
WILL BRING RAIN BACK TO THE REGION LATE THURSDAY THROUGH
FRIDAY...YET RAINFALL AMOUNTS ARE EXPECTED TO GENERALLY BE LIGHT. A
RIDGE OF HIGH PRESSURE WILL THEN BUILD OVER MUCH OF THE STATE AND
RESULT IN DRY...SEASONAL WEATHER CONDITIONS.

&&

.DISCUSSION...AS OF 01:58 PM PST WEDNESDAY...LINGERING SHOWERS
CONTINUE TO INCREASE IN COVERAGE THIS AFTERNOON AS A WEAK
MID/UPPER LEVEL DISTURBANCE APPROACHES THE REGION. THIS WILL ALLOW
FOR ISOLATED TO SCATTERED SHOWERS TO CONTINUE THROUGH THE EVENING
WITH GENERALLY LIGHT RAINFALL AMOUNTS. ADDITIONAL RAINFALL AMOUNTS
OF 0.10" TO 0.15" IN URBAN AREAS WITH THE COASTAL RANGES PICKING
UP AS MUCH AS 0.25" TO 0.50" OF RAIN THROUGH TONIGHT. A BIT OF A
LULL IN PRECIPITATION IS EXPECTED ON THURSDAY ON THE BACK SIDE OF
THE EXITING MID/UPPER LEVEL TROUGH.

CHANCES FOR PRECIPITATION ONCE AGAIN INCREASE THURSDAY NIGHT INTO
FRIDAY AS THE NEXT PACIFIC SYSTEM APPROACHES THE PACIFIC NORTHWEST.
THIS FEATURE WILL PUSH ANOTHER FRONTAL BOUNDARY INTO THE NORTH BAY
LATE THURSDAY NIGHT AND THEN SOUTHWARD DURING THE DAY ON FRIDAY.
PWAT VALUES ARE FORECAST TO BE JUST ABOVE THE 1 INCH MARK...YET THE
MID/UPPER LEVEL SUPPORT WILL NOT BE ALL THAT STRONG. WITH THAT
SAID...ONLY EXPECTING WIDESPREAD RAINFALL AMOUNTS TO BE AROUND 0.50"
TO 1.00" IN THE NORTH BAY...GENERALLY BELOW 0.50" OVER THE SAN
FRANCISCO BAY AREA AND 0.25" OR LESS SOUTH OF THE SANTA CRUZ
MOUNTAINS. A FEW SHOWERS MAY LINGER OVER THE NORTH BAY THROUGH
SATURDAY...YET A MAJORITY OF THE REGION IS FORECAST TO BEGIN A
DRYING TREND.

BY EARLY NEXT WEEK...A RIDGE OF HIGH PRESSURE WILL BUILD OVER THE
EASTERN PACIFIC AND BRING DRY CONDITIONS TO THE REGION. DAYTIME
TEMPERATURES WILL ALSO WARM SLIGHTLY UNDER PARTLY CLOUDY CONDITIONS.
THE RIDGE IS FORECAST TO REMAIN IN PLACE THROUGH MIDWEEK AND WILL
ALLOW FOR SOME DRYING OF THE VERY SATURATED SOILS CAUSED BY THE
MUCH NEEDED RECENT RAINFALL. THE FORECAST MODELS THEN DIVERGE LATE
NEXT WEEK ON THE UPPER LEVEL PATTERN. THE ECMWF AND GEM PUSH A
STRONGER MID/UPPER LEVEL SYSTEM INTO THE PACIFIC NORTHWEST WITH A
COLD AIRMASS DROPPING SOUTHWARD. MEANWHILE...THE GFS DOES BREAK DOWN
THE RIDGE SLIGHTLY...YET PUSHES THE MUCH COLDER AIR MASS DOWN INTO
THE CENTRAL PLAINS. OVERALL...NO MAJOR WEATHER CONCERNS ANTICIPATED
ACROSS THE REGION FOR CHRISTMAS.

&&

.AVIATION...AS OF 4:00 PM PST WEDNESDAY...THE NEXT BAND OF RAIN
SHOWERS IS ON THE WAY WITH BORDERLINE MVFR/VFR CIGS ANTICIPATED.
LIGHT TO MODERATE RAIN EXPECTED OVER THE AREA TERMINALS BETWEEN
02Z AND 06Z THIS EVENING. SHOWERS WILL DIMINISH OVERNIGHT.
ABUNDANT LOW LEVEL MOISTURE IS EXPECTED TO BRING LOWER CIGS
OVERNIGHT. CONFIDENCE IS MODERATE.

VICINITY OF KSFO...BORDERLINE VFR/MVFR CIGS WITH LIGHT TO MODERATE
RAIN EXPECTED ACROSS THE BAY AREA THROUGH 06Z TONIGHT. SHOWERS
WILL TAPER OVERNIGHT. SOUTHERLY WINDS WILL PREVAIL.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...BORDERLINE VFR/MVFR CIGS WITH LIGHT TO
MODERATE RAIN EXPECTED ACROSS THE MONTEREY BAY AREA THROUGH 08Z
TONIGHT. SHOWERS WILL TAPER OVERNIGHT. SOUTHERLY WINDS WILL
PREVAIL.

&&

.MARINE...AS OF 2:46 PM PST WEDNESDAY...SOUTHERLY WINDS ARE EXPECTED
TO PREVAIL THIS EVENING AS A COLD FRONT PASSES OVER THE WATERS. WINDS
ARE ANTICIPATED TO BE LIGHT BEGINNING FRIDAY AS HIGH PRESSURE
BUILDS OVER THE AREA BETWEEN STORM SYSTEMS. A LARGE...LONG PERIOD
WESTERLY SWELL WILL IMPACT THE COAST FRIDAY AFTERNOON LASTING INTO
THE WEEKEND.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...SCA...PIGEON PT TO PT PINOS 0-10 NM UNTIL 10 PM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM UNTIL 10 PM
             SCA...PIGEON PT TO PT PINOS 10-60 NM UNTIL 10 PM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 10-60 NM UNTIL 10 PM
             SCA...PT ARENA TO PT REYES 0-10 NM UNTIL 10 PM
             SCA...PT ARENA TO PT REYES 10-60 NM UNTIL 10 PM
             SCA...PT REYES TO PIGEON PT 10-60 NM UNTIL 10 PM
             SCA...PT REYES TO PIGEON PT 0-10 NM UNTIL 1 AM

&&

$$

PUBLIC FORECAST: RGASS
AVIATION: CW
MARINE: LARRY/MM

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