High Surf in California, December 28 to 29, 2007

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
1050 PM PST THU DEC 27 2007

UPDATED AVIATION DISCUSSION

.DISCUSSION...COLD OVERNIGHT LOWS AND MOSTLY CLOUDY SKIES TODAY
RESULTED IN COOL DAYTIME TEMPERATURES. HIGHS TODAY WERE MOSTLY
AROUND THE 50 DEGREE MARK WITH SEVERAL LOCATIONS NOT MAKING IT OUT
OF THE 40S.

THE SYSTEM DROPPING IN FROM THE NORTHWEST HAD SPREAD LIGHT RAIN
ACROSS MOST OF THE SF BAY AREA BY 8 PM. WITH THE COLD AIRMASS IN
PLACE AHEAD OF THIS SYSTEM...THERE HAVE BEEN REPORTS OF SNOW AT
HIGHER ELEVATIONS. SNOW IS STICKING TO THE ROAD AT THE 2300 FOOT
LEVEL ON HIGHWAY 29 IN NORTHERN NAPA COUNTY. ALSO...SNOW HAS BEEN
REPORTED AT THE 2400 FOOT LEVEL 7 MILES EAST OF THE HIGHWAY 17 SUMMIT
IN THE SANTA CRUZ MOUNTAINS. SNOW LEVELS SHOULD GRADUALLY RISE
OVERNIGHT AS WARM ADVECTION CONTINUES...BUT WOULDNT BE SURPRISED TO
SEE SNOW LOCALLY AS LOW AS 1500 FEET GIVEN THE COLD AIR CURRENTLY
TRAPPED UNDER THE FRONTAL INVERSION.

RAINFALL SHOULD MOSTLY END BY LATE MORNING FRIDAY AND PARTIAL
AFTERNOON CLEARING IS EXPECTED. BUT DRY WEATHER WONT LAST LONG AS
THE NEXT SYSTEM RAPIDLY APPROACHES FROM THE NORTHWEST. RAINFALL
ONSET WITH THAT ONE WILL BE ABOUT 24 HOURS AFTER THE CURRENT
SYSTEM...WITH RAIN EXPECTED TO SPREAD INTO THE NORTH BAY BY LATE
AFTERNOON...AND OVER THE REST OF THE FORECAST AREA FRIDAY EVENING.
LIGHT RAIN MAY LINGER IN SPOTS THROUGH SATURDAY MORNING...AND EVEN
INTO SATURDAY AFTERNOON. BUT BY LATE SATURDAY PRECIP SHOULD END IN
ALL AREAS.

RAINFALL TOTALS THROUGH SATURDAY MORNING ARE FORECAST TO RANGE FROM A
HALF INCH TO AN INCH IN THE NORTH BAY...A QUARTER TO A HALF INCH
ELSEWHERE IN THE SF BAY AREA...AND A TENTH TO A QUARTER INCH ACROSS
MONTEREY/SAN BENITO COUNTIES.

ALTHOUGH THESE SYSTEMS ARE APPROACHING FROM THE NORTHWEST...MOST
PRECIP WILL BE THE RESULT OF WARM ADVECTION AND THE AIRMASS OVER OUR
REGION WILL GRADUALLY WARM OVER THE NEXT TWO DAYS. TEMPERATURES
WILL BE SEVERAL DEGREES WARMER BY SATURDAY THAN WHAT WE SAW TODAY.

DRY WEATHER IS EXPECTED FROM SUNDAY INTO THE FIRST HALF OF NEXT WEEK
AS AN UPPER RIDGE OVER THE EASTERN PAC MOVES INTO THE WESTERN U.S..
BUT THE WEATHER PATTERN IS FORECAST TO CHANGE IN A BIG WAY DURING
THE SECOND HALF OF NEXT WEEK AS A BROAD UPPER TROUGH AND LONG FETCH
OF VERY MOIST AIR APPROACH THE WEST COAST. THE 12Z ECMWF SHOWS THE
INITIAL RAIN EVENT ARRIVING AS EARLY AS WEDNESDAY AFTERNOON AND THE
00Z GFS IS ONLY SLIGHTLY SLOWER. THE GFS HAS BEEN TRENDING A LITTLE
DRIER WITH THE INITIAL RAIN EVENT. HOWEVER...BOTH THE GFS AND ECMWF
HAVE BEEN SHOWING A VERY WET PATTERN FOR MOST OF CA FOR THE SECOND
HALF OF NEXT WEEK AND INTO THE FOLLOWING WEEKEND FOR THREE DAYS
NOW. ALTHOUGH THIS IS STILL OUT IN THE 6-10 DAY TIME FRAME...
CONFIDENCE IS REASONABLY HIGH THAT A MAJOR PRECIP EVENT COULD OCCUR
BETWEEN JAN 3RD AND 7TH GIVEN THE MODEL AGREEMENT AND CONSISTENCY.

.AVIATION...WARM AIR ADVECTION PRECIPITATION CONTINUES TO SPREAD
SOUTH AND EAST PER RADAR DATA. THE 00Z OAKLAND SOUNDING SHOWED
FREEZING LEVELS WERE DOWN TO 3500 FEET. 00Z SOUNDING ALSO CAPTURED
THE WARM FRONTAL INVERSION NEAR 8 THOUSAND FEET. A COLD FRONT JUST
NORTH OF THE AREA WILL CONTINUE TO PRESS SOUTHWARD OVERNIGHT. SHOWERS
WILL CONTINUE INTO FRIDAY WITH PERHAPS A RENEWED STEADY RAIN EVENT
DEVELOPING FRI EVENING OVER THE NORTH BAY AS ADDITIONAL 500 MB
SHORTWAVE ENERGY TRAVELS IN ON NW FLOW.

.MTR WATCHES/WARNINGS/ADVISORIES...
   .TNGT...SCA...POINT ARENA TO POINT PIEDRAS BLANCAS AND MRY BAY.
        ...ROUGH BAR

PUBLIC FORECAST: DYKEMA
AVIATION/MARINE: CANEPA

NWS ON THE WEB AT WEATHER.GOV/SANFRANCISCO

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
434 AM PST THU DEC 27 2007

CAZ006-505>518-PZZ530-535-281245-
SAN FRANCISCO-
COASTAL NORTH BAY...INCLUDING POINT REYES NATIONAL SEASHORE-
NORTH BAY INTERIOR VALLEYS-NORTH BAY MOUNTAINS-
SAN FRANCISCO BAY SHORELINE-SAN FRANCISCO PENINSULA COAST-
EAST BAY INTERIOR VALLEYS-EAST BAY HILLS AND DIABLO RANGE-
SANTA CRUZ MOUNTAINS-SANTA CLARA VALLEY...INCLUDING SAN JOSE-
MONTEREY BAY...NORTHERN SALINAS VALLEY...HOLLISTER VALLEY...AND
CARMEL VALLEY-BIG SUR COAST-
SOUTHERN SALINAS VALLEY...ARROYO SECO...AND LAKE SAN ANTONIO-
SANTA LUCIA MOUNTAINS AND LOS PADRES NATIONAL FOREST-
MOUNTAINS OF SAN BENITO AND INTERIOR MONTEREY COUNTY INCLUDING
PINNACLES NATIONAL MONUMENT-
SAN FRANCISCO/SAN PABLO/SUISUN BAYS AND THE WEST DELTA-
MONTEREY BAY-
434 AM PST THU DEC 27 2007

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CA AND PACIFIC
COASTAL WATERS.

.DAY ONE...TODAY AND TONIGHT

A PACIFIC STORM SYSTEM WILL BEGIN TO SPREAD RAIN ACROSS CENTRAL
CALIFORNIA TODAY. PRECIPITATION IS EXPECTED TO BEGIN IN SONOMA
COUNTY LATE THIS MORNING AND SPREAD TO THE SOUTH THROUGH THE DAY.
BY LATE THIS EVENING ALL AREAS OF THE CENTRAL COAST ARE FORECAST
TO HAVE RAIN. TOTAL RAINFALL AMOUNTS BY TONIGHT SHOULD BE GREATER FOR
AREAS NORTH OF SAN FRANCISCO WHERE BETWEEN A QUARTER AND HALF AN INCH
OF RAIN MAY FALL.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

RAIN IS EXPECTED TO DISSIPATE THE FIRST HALF OF FRIDAY BEFORE
ANOTHER STORM PUSHING INTO CENTRAL CALIFORNIA TOWARD FRIDAY
EVENING. RAINFALL IS AGAIN FORECAST TO BE THE HIGHEST FOR
LOCATIONS NORTH OF SAN FRANCISCO. NICE WEATHER WILL RETURN TO OUR
AREA FOR THE FIRST HALF OF NEXT WEEK

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS TO THEIR LOCAL NATIONAL WEATHER SERVICE OFFICE.