Flash Flood Watch 1, NWS San Francisco Bay Area, CA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
907 AM PST MON DEC 25 2006

.DISCUSSION...MOIST PLUME OF MOISTURE...GREATER THAN 1.5 INCHES TPW
PER THE AMSU IMAGERY IS CURRENTLY AIMED AT NORTHWEST CALIFORNIA.
OVER THE DISTRICT VALLEY FOG IS PREVALENT...WITH VIS DOWN TO 1/8
MILE AT SAN JOSE...AND DOWN TO 1 MILE IN THE EAST BAY...AND 2 MILES
IN THE PENINSULA.

WILL BE UPDATING THE FORECAST TO TAKE OUT THE RAIN FOR TODAY...AS
THE GFS IS TAKING ITS SWEET TIME MOVING THE SYSTEM SOUTH. WILL ALSO
ADD DENSE FOG TO THE ZONES AND DROP TEMPS IN THE EAST BAY.

THE LATEST GFS IS BRINGING COPIOUS AMOUNTS OF RAIN TO THE DISTRICT
AS STRONG ISENTROPIC LIFT SETS UP. AS A SURFACE LOW DEVELOPS ALONG
THE BOUNDARY ON TUESDAY...IN RESPONSE TO A SHORTWAVE MOVING ACROSS...
THE GRADIENT TIGHTENS UP. WILL BE TAKING A CLOSE LOOK TO SEE IF A
HIGH WIND WATCH WILL BE NEEDED FOR TUESDAY.

UPDATES BY 915 AM.

&&

.AVIATION...FOR SF BAY AREA TERMINALS...RELATIVE HUMIDITIES
INCREASED AS OFFSHORE FLOW BROUGHT IN LOW LEVEL MOISTURE FROM THE
CENTRAL VALLEY. VISIBILITIES CONTINUE TO RANGE FROM 2-4 MILES BUT
LITTLE IMPROVEMENT IS EXPECTED UNTIL LATE THIS AFTERNOON AS WINDS
START TO PICK UP FROM THE SOUTHEAST AHEAD OF THE SLOWLY MOVING
FRONT. UNFORTUNATELY LIFR CONDITIONS AT KSJC ARE NOT EXPECTED TO
IMPROVE UNTIL MID AFTERNOON AS STAGNANT CONTITIONS ARE TRAPPED IN
THE SANTA CLARA VALLEY WITH LIGHT WINDS AND HIGHER CLOUDS ACROSS
THE AREA CAPPING THE INVERSION. RAIN SHOULD START AFFECTING STS
BETWEEN 08-10Z TUESDAY MOVING SOUTHWARD TOWARDS OAK...SFO...AND SJC
BETWEEN 10-12Z. CIGS WILL LOWER WITH THE RAIN AROUND 2000-4000 FT.

FOR MONTEREY BAY AREA TERMINALS...VFR CONDITIONS EXPECTED
THROUGH THE DAY. MID AND UPPER LEVEL CLOUDS SHOULD START MOVING OVER
THE AREA LATER THIS MORNING...BUT LOWER CIGS AND RAIN ARE NOT
EXPECTED UNTIL TUESDAY MORNING AFTER 12Z.

.MARINE...A DEEP LOW IN THE GULF OF ALASKA HAS GENERATED LARGE SWELLS
THAT WILL HIT MAINLY THE PACIFIC NORTHWEST...BUT SWELLS ALONG OUR
WATERS ARE EXPECTED TO BUILD TO 13 TO 16 FEET BY TONIGHT. ANOTHER LOW
SEVERAL HUNDRED MILES OFF THE OREGON COAST IS FORECAST TO INTENSIFY
RAPIDLY AND GENERATE ANOTHER SET OF LARGE SWELLS THAT WILL REACH OUR
COASTAL WATERS TUESDAY NIGHT AND WEDNESDAY. THIS COMBINED WITH
STRONG SE WINDS AT THAT TIME COULD RESULT IN VERY LARGE COMBINED
SEAS. LATEST FORECAST CALLS FOR SWELLS IN THE 14 TO 17 FOOT RANGE
WEDNESDAY.

.MTR...WATCHES/WARNINGS/ADVISORIES...NONE.

PUBLIC FORECAST: STROBIN
AVIATION/MARINE: ANDERSON

NWS ON THE WEB AT WEATHER.GOV/SANFRANCISCO

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
402 AM PST MON DEC 25 2006

CAZ505>507-261215-
COASTAL NORTH BAY...INCLUDING POINT REYES NATIONAL SEASHORE-
NORTH BAY INTERIOR VALLEYS-NORTH BAY MOUNTAINS-
402 AM PST MON DEC 25 2006

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CA.

.DAY ONE...TODAY AND TONIGHT

RAIN WILL BE DEVELOPING BY TONIGHT. MINOR URBAN AND SMALL STREAM
HYDROLOGY ISSUES ARE POSSIBLE LATE AT NIGHT.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

STEADY RAINS DEVELOP TUESDAY...AND MAY BE HEAVY AT TIMES. THE
STORM MAY PRODUCE 3 TO 5 INCHES OF RAIN WITH LOCAL AMOUNTS UP TO 6
INCHES POSSIBLE. URBAN AND SMALL STREAM HYDROLOGY ISSUES ARE STILL
POSSIBLE ALL DAY TUESDAY. GUSTY WINDS ARE ALSO POSSIBLE. ON
WEDNESDAY THE STORM DIES DOWN WITH LINGERING SHOWERS STILL MOVING
OVER THE AREA. THURSDAY THROUGH SUNDAY PARTLY CLOUDY EXCEPT FRIDAY
WHEN THERE IS A SLIGHT CHANCE OF SHOWERS.

CAZ006-508>518-261215-
SAN FRANCISCO-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-
402 AM PST MON DEC 25 2006

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CA.

.DAY ONE...TODAY AND TONIGHT

LIGHT RAIN WILL BE DEVELOPING LATE TONIGHT IN THE NORTHERN PART
OF THE AREA.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

STEADY RAINS DEVELOP TUESDAY...AND MAY BE HEAVY AT TIMES. THE
STORM MAY PRODUCE 3 TO 5 INCHES OF RAIN WITH LOCAL AMOUNTS UP TO 6
INCHES POSSIBLE. URBAN AND SMALL STREAM HYDROLOGY ISSUES ARE STILL
POSSIBLE ALL DAY TUESDAY. GUSTY WINDS ARE POSSIBLE AS WELL. ON
WEDNESDAY THE STORM DIES DOWN WITH LINGERING SHOWERS STILL MOVING
OVER THE AREA. PARTLY CLOUDY THURSDAY THROUGH SUNDAY.