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

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FXUS66 KMTR 200548
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
948 PM PST FRI DEC 19 2014

.SYNOPSIS...SCATTERED SHOWERS CAN BE EXPECTED THROUGH THE EVENING
HOURS WITH A FEW FORECAST TO LINGER INTO SATURDAY ESPECIALLY NORTH
OF SAN FRANCISCO. THIS WILL BE FOLLOWED BY A RIDGE OF HIGH PRESSURE
BUILDING OVER THE WEST COAST RESULTING IN A DRYING AND WARMING TREND
THROUGH AT LEAST MOST OF NEXT WEEK.

&&

.DISCUSSION...AS OF 08:40 PM PST FRIDAY...RAIN SHOWERS CONTINUE
FROM THE SANTA CRUZ MOUNTAINS INLAND THROUGH MUCH OF SANTA CLARA
COUNTY AND SOUTHWARD DOWN COASTAL MONTEREY COUNTY THIS EVENING.
FURTHER NORTH...SHOWERS HAVE DIMINISHED IN COVERAGE AND MOST SITES
ARE NO LONGER REPORTING RAINFALL. THIS IS MAINLY DUE TO A WASHED
OUT FRONT THAT MOVED ACROSS THE REGION EARLIER TODAY...WITH PWAT
VALUES ESTIMATED TO BE BETWEEN 1.00" TO 1.20" ALONG THE CENTRAL
COAST. EXPECTING THESE SHOWERS TO CONTINUE THROUGH LATE EVENING
BEFORE TAPERING OFF EARLY SATURDAY MORNING. RAIN CHANCES PICK BACK
UP SATURDAY MORNING OVER THE NORTH BAY AS ANOTHER WEAK MID/UPPER
LEVEL DISTURBANCE PUSHES INTO NORTHERN CALIFORNIA AND INTERACTS
WITH DEEPER MOISTURE ADVECTING INTO THE REGION. HAVE MADE A FEW
MINOR CHANGES TO THE FORECAST TO REFLECT THE ABOVE REASONING.

&&

.PREV DISCUSSION...AS OF 3:00 PM PST FRIDAY...RADAR SHOWS THAT THE
MODERATE TO HEAVY RAIN WE HAD EARLIER OVER THE NORTH BAY HAS
SLOWLY SHIFTED TO THE SOUTH AND DISSIPATED THROUGH THE AFTERNOON.
FOR WHAT APPEARS TO BE A NON-EVENT...RAINFALL AMOUNTS HAVE BEEN
SURPRISINGLY ROBUST OVER THE NORTH BAY WITH A FEW STATIONS PICKING
UP THAN 2 INCHES SINCE MIDNIGHT. URBAN LOCATIONS HAVE ALSO
BENEFITED WITH SAN FRANCISCO PICKING UP NEARLY AN INCH IN THE
PERIOD. ADDITIONAL AMOUNTS SHOULD BE LIGHT ALTHOUGH WOULD NOT BE
SURPRISED IF PORTIONS OF SANTA CRUZ AND SANTA CLARA COUNTIES PICK
UP A QUARTER OF AN INCH OR MORE INTO THE EVENING HOURS. MOST SPOTS
IN MONTEREY COULD WILL LIKELY COME IN WITH SMALLER VALUES --
GENERALLY UP TO 0.15 INCHES. A FEW SHOWERS WILL CONTINUE INTO THE
OVERNIGHT HOURS WITH LIGHT AMOUNTS FORECAST.

FOR THE UPCOMING WEEKEND DRIER WEATHER WITH SOME WARMING CAN BE
EXPECTED AS A RIDGE OF HIGH PRESSURE NUDGES INTO OUR CWA AND THE
STORM TRACK HEADS BACK TO OUR NORTH. GUIDANCE CONTINUES TO SHOW
POSSIBLE SHOWERS ESPECIALLY FOR THE NORTH BAY ON SATURDAY ALTHOUGH
ANY ADDITIONAL AMOUNTS SHOULD BE LIGHT -- GENERALLY UNDER A TENTH.
CLOUDS WILL ALSO BE ON THE DECREASE AND SHOULD ALLOW FOR SOME
PEAKS OF SUNSHINE ESPECIALLY FROM SANTA CRUZ COUNTY TO THE SOUTH.
BY SUNDAY MOST LOCATIONS WILL BE BACK IN THE 60S.

ADDITIONAL WARMING IS FORECAST FOR MONDAY AND TUESDAY AS THE RIDGE
BUILDS JUST OFF OUR COAST AND 850 MB TEMPS INCREASE. TUESDAY
SHOULD BE THE WARMEST DAY FOR NEXT WEEK WITH 60S TO LOWER 70S IN
THE CARDS. POSSIBLE A FEW ISOLATED MID 70S WILL APPEAR IN SOUTHERN
MONTEREY COUNTY.

FOR WEDNESDAY -- CHRISTMAS EVE -- AN INSIDE SLIDER WILL DROP DOWN
INTO THE PACNW/NORCAL REGION AND EVENTUALLY HEAD INTO SOUTHERN
NEVADA WEDNESDAY NIGHT. AS THE SYSTEM DROPS DOWN IT WILL MOSTLY
BRING COOLER AIR WITH IT HOWEVER A FEW SHOWERS MAY BE TRIGGERED
ESPECIALLY OVER THE NORTH BAY. POPS WERE PUSHED UP FOR THIS PERIOD.

FOR THE REST OF NEXT WEEK A DRY AND SEASONABLY COOL NW FLOW WILL
REMAIN IN PLACE. LATEST 8 TO 14 DAY OUTLOOK THROUGH JANUARY 2ND
ALSO FAVORS DRIER THAN NORMAL WEATHER WHICH WILL HELP TO MAKE
TRAVEL EASIER FOR THOSE ON THE ROADS DURING THE HOLIDAY SEASON.
&&

.AVIATION...AS OF 9:48 PM PST FRIDAY...A COLD FRONT CONTINUES TO
PASS OVER THE FORECAST AREA. PRECIPITATION IS NOW CONFINED TO SOUTH
OF THE SAN FRANCISCO BAY AREA. THE FRONT IS NO LONGER EXPECTED TO
BE STRONG ENOUGH TO MIX THE LOW CLOUDS OUT SO EXPECT MVFR CIGS AT
MOST TERMINALS OVERNIGHT. RAIN SHOULD END SHORTLY IN THE SAN JOSE
AREA BUT STICK AROUND UNTIL THE EARLY MORNING HOURS IN MONTEREY.


VICINITY OF KSFO...MVFR CIGS WILL PREVAIL THROUGH AROUND 1900Z
SATURDAY. ONCE THE CLOUDS LIFT ON SATURDAY VFR IS ANTICIPATED INTO
THE EVENING HOURS. WINDS ARE EXPECTED TO BE GENERALLY LIGHT
SOUTHERLY THROUGH THE FORECAST PERIOD.

CONFIDENCE IS MODERATE.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...MVFR CIGS AND LIGHT RAIN ARE
ANTICIPATED OVERNIGHT WITH RAIN ENDING BY SUN RISE. VFR IS
ANTICIPATED BY AROUND 1800Z SATURDAY.

CONFIDENCE IS MODERATE.

&&

.MARINE...AS OF 8:40 PM PST FRIDAY...A STRONG STORM SYSTEM MOVING
THROUGH THE GULF OF ALASKA HAS GENERATED A LARGE LONG PERIOD
WESTERLY SWELL. THIS SWELL WILL MOVE INTO THE WATERS OVERNIGHT
TONIGHT AND CONTINUE TO BUILD ON SATURDAY. SWELLS ARE EXPECT TO
BEGIN TO DECREASE SATURDAY AFTERNOON. THE LARGE LONG PERIOD SWELL
WILL RESULT IN LARGE BREAKING WAVES ACROSS THE SAN FRANCISCO BAR
AND OFFSHORE REEFS AND ROCK OUTCROPPINGS. MARINERS ARE URGED TO
USE CAUTION WHILE NAVIGATING THE WATERS TONIGHT INTO SATURDAY.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...HIGH SURF ADVISORY...THE COASTLINE FROM SONOMA COUNTY
                                  SOUTH THROUGH MONTEREY COUNTY.
             SCA...PT ARENA TO PT REYES 0-10 NM
             SCA...PT REYES TO PIGEON PT 0-10 NM
             SCA...PIGEON PT TO PT PINOS 0-10 NM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM
             SCA...PT ARENA TO PT REYES 10-60 NM
             SCA...PT REYES TO PIGEON PT 10-60 NM
             SCA...PIGEON PT TO PT PINOS 10-60 NM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 10-60 NM
             SCA...ROUGH BAR ADVISORY FOR SF BAR FROM 10 PM

&&

$$

PUBLIC FORECAST: RGASS
AVIATION/MARINE: LARRY

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