Flash Flood Watch 3, NWS San Francisco Bay Area, CA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
243 PM PST SUN DEC 23 2012

.DISCUSSION...AS OF 2:00 PM PST SUNDAY...RADAR...SFC OBS...AND
SATL IMAGERY IS SHOWING THAT THE COLD FRONT IS MOVING THROUGH THE
HEART OF THE SAN FRANCISCO BAY AREA AT THIS TIME. HEAVY RAIN IS
CURRENTLY BEING REPORTED AT HAYWARD AND REDWOOD CITY. WINDS HAVE
DECREASED AS THE COLD FRONT CONTINUE TO MOVE THROUGH...THEREFORE
THE WIND ADVISORIES HAVE BEEN ALLOWED TO EXPIRE...OR HAVE BEEN
CANCELLED. WATER VAPOR IMAGERY IS INDC GOOD SUBSIDENCE BEHIND THE
FRONT SO THERE COULD BE SOME CLEARING LATE THIS AFTN...AND IN FACT
UKIAH HAS PARTLY CLOUDY SKIES.

DUE TO THE HEAVY RAIN THERE ARE A VARIETY OF MAINSTEM FLOOD
WARNINGS...FLOOD WATCHES...FLASH FLOOD WARNINGS...AND FLASH FLOOD
WATCHES. PLEASE SEE OUR HOMEPAGE FOR THE LATEST INFORMATION
(WWW.WEATHER.GOV/SANFRANCISCO).

HAVE CONTINUED THE THREAT OF SHOWERS THIS EVENING ACROSS THE
DISTRICT...BUT BASED ON THE LATEST MODEL AND SATELLITE IMAGERY THE
FORECAST COULD BE A LITTLE TOO PESSIMISTIC. ANY SHOWER ACTIVITY
SHOULD END OVERNIGHT AS THE COLD FRONT AND ASSOCIATED UPPER TROUGH
MOVES TO THE EAST.

CHRISTMAS EVE LOOKS LIKE IT WILL BE DRY AS WEAK RIDGING MOVES
OVERHEAD. THE NEXT SHORTWAVE MOVES TO THE COAST ON CHRISTMAS
DAY...WITH RAIN DEVELOPING IN THE NORTH BAY DURING THE MORNING...
AND SPREADING SOUTH DURING THE AFTERNOON. THIS SYSTEM WILL NOT BE
AS STRONG...BUT WILL BE SLOWER MOVING. RAIN WILL CONTINUE ACROSS
THE DISTRICT CHRISTMAS EVENING...TURNING TO SHOWERS CHRISTMAS
NIGHT. SINCE THIS SYSTEM WILL BE COLDER...INSTABILITY SHOWERS ARE
POSSIBLE RIGHT THROUGH WEDNESDAY NIGHT. THERE COULD BE A FEW
SHOWERS ON THURSDAY...BUT THEY SHOULD BE FEW AND FAR BETWEEN.

WEAK RIDGING WILL BRING DRY WEATHER THURSDAY NIGHT. MEDIUM RANGE
MODELS DISAGREE LATE IN THE WEEK. A TROUGH DROPS SOUTH OUT OF THE
GULF OF ALASKA AND SHEARS OFF A CUT-OFF UPPER LOW. THE ECMWF HAS
THE LOW MOVING OVER THE DISTRICT WHEREAS THE GFS HAS IT OFFSHORE.

&&

.AVIATION...AS OF 9:50 AM PST SUNDAY...COLD FRONT CONTINUES TO
ADVANCE TOWARD OUR AREA AND IS RUNNING A FEW HOURS AHEAD OF
EARLIER GUIDANCE. ADJUSTED ALL TAFS FOR QUICKER SWITCH OF WINDS
AND CHANGE OF WIDESPREAD RAIN TO SHOWERS. VERY GUSTY CONDITIONS
LIKELY AS THE FRONT GOES THROUGH. THUNDER ALSO NOT OUT OF THE
QUESTION ALTHOUGH SO FAR NO STRIKES HAVE BEEN DETECTED. MUCH
IMPROVED CONDITIONS BY LATE THIS AFTERNOON. ONLY REMAINING ISSUE
AROUND STS FOR TONIGHT AS FOG LOOKS LIKELY. MODERATE CONFIDENCE.

VICINITY OF KSFO...FRONT SHOULD GO THROUGH SOME TIME BETWEEN 20 AND
21Z. BEFORE THAT MODERATE SOUTH TO SOUTHEAST WINDS WILL CONTINUE
WITH GUSTS UP TO 40 KT POSSIBLE. PIREP FROM CWSU MENTIONED UP TO
20 KT OF SPEED SHEER AROUND 200 FEET SO ADDED LLWS FOR THE FIRST
GROUP. BAND OF RAIN WILL ALSO PRODUCE VIS DOWN TO 2SM AT TIMES.
MUCH IMPROVED WEATHER LATER TODAY BEHIND THE FRONT WITH RAIN
MOSTLY OVER AFTER 02Z. MVFR CIGS WILL STAY AROUND THROUGH THE
EVENING. MODERATE CONFIDENCE.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...RAIN THROUGH THE EARLY AFTERNOON
WITH GUSTY SOUTHEAST WINDS (POSSIBLY GUSTING TO 40 KT AT THE PEAK).
RADAR SHOWS POCKETS OF MODERATE RAINFALL MOVING TO THE AREA SO VIS
COULD DROP DOWN TO 2SM WITH HEAVY RAIN AT TIMES. CONDITIONS
IMPROVE BY LATE THIS AFTERNOON WITH LESS RAIN AND WINDS PLUS VFR
CIGS. LOW TO MODERATE CONFIDENCE.

&&

.MARINE...AS OF 9:50 AM PST SUNDAY...GUSTY SOUTHERLY WINDS WILL
CONTINUE AS A COLD FRONT MOVES ACROSS OUR AREA. LOCAL WINDS WILL
GUST INTO THE GALE FORCE CATEGORY. THESE WINDS WILL GENERATE
STEEP FRESH SWELLS...WITH COMBINED SEAS BUILDING TO 16 TO 18 FEET
BY SUNDAY AFTERNOON. CONDITIONS WILL BEGIN TO IMPROVE BY LATE THIS
AFTERNOON.

WINDS AND SEAS WILL QUICKLY SUBSIDE THIS EVENING INTO MONDAY
MORNING AS THE STORM SYSTEM PASSES TO THE SOUTH.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...SCA...PIGEON PT TO PT PINOS 0-10 NM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM
             SCA...PIGEON PT TO PT PIEDRAS BLANCAS 10-60 NM
             SCA...PT ARENA TO PIGEON PT 10-60 NM
             SCA...PT ARENA TO PT REYES 0-10 NM
             SCA...PT REYES TO PIGEON PT 0-10 NM
             SCA...ROUGH BAR ADVISORY FOR SF BAR
             SCA...SF BAY
             SCA...MRY BAY

&&

PUBLIC FORECAST: STROBIN
AVIATION/MARINE: BELL

VISIT US AT WWW.WEATHER.GOV/SANFRANCISCO

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HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
540 AM PST SUN DEC 23 2012

CAZ006-505>507-509-241400-
SAN FRANCISCO-
COASTAL NORTH BAY...INCLUDING POINT REYES NATIONAL SEASHORE-
NORTH BAY INTERIOR VALLEYS-NORTH BAY MOUNTAINS-
SAN FRANCISCO PENINSULA COAST-
540 AM PST SUN DEC 23 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SAN FRANCISCO BAY AREA AND
MONTEREY BAY AREA.

.DAY ONE...SUNDAY AND SUNDAY NIGHT

SOUTHERLY WINDS WILL INCREASE ACROSS THE AREA TODAY WITH WIND
GUSTS AS HIGH AS 50 MPH ARE POSSIBLE. A WIND ADVISORY IS IN EFFECT
THROUGH 1 PM PST SUNDAY. LOCALLY HEAVY RAIN COULD RESULT IN LOCAL
FLOODING OF SMALL STREAMS AND CREEKS AS WELL AS ROADS.

*  WIND ADVISORY.....SEE SFONPWMTR WWUS76 KMTR FOR DETAILS  *

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

DRY WEATHER IS FORECAST MONDAY BEFORE ANOTHER CHANCE OF RAIN
ARRIVES BY CHRISTMAS AFTERNOON.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS PER STANDARD OPERATING PROCEDURES.

CAZ508-510>512-241400-
SAN FRANCISCO BAY SHORELINE-EAST BAY INTERIOR VALLEYS-
EAST BAY HILLS AND DIABLO RANGE-SANTA CRUZ MOUNTAINS-
540 AM PST SUN DEC 23 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SAN FRANCISCO BAY AREA AND
MONTEREY BAY AREA.

.DAY ONE...SUNDAY AND SUNDAY NIGHT

SOUTHERLY WINDS WILL INCREASE ACROSS THE AREA TODAY WITH WIND
GUSTS AS HIGH AS 45 MPH POSSIBLE. A WIND ADVISORY IS IN EFFECT
THROUGH 1 PM PST SUNDAY. IN ADDITION THERE WILL BE PERIODS OF
MODERATE RAIN.

*  WIND ADVISORY.....SEE SFONPWMTR WWUS76 KMTR FOR DETAILS  *

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

DRY WEATHER IS FORECAST MONDAY BEFORE ANOTHER CHANCE OF RAIN
ARRIVES BY CHRISTMAS EVENING.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS PER STANDARD OPERATING PROCEDURES.

CAZ528>530-241400-
NORTHERN SALINAS VALLEY...HOLLISTER VALLEY...AND CARMEL VALLEY-
NORTHERN MONTEREY BAY-SOUTHERN MONTEREY BAY AND BIG SUR COAST-
540 AM PST SUN DEC 23 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SAN FRANCISCO BAY AREA AND
MONTEREY BAY AREA.

.DAY ONE...SUNDAY AND SUNDAY NIGHT

STRONG AND GUSTY SOUTHERLY WINDS ARE EXPECTED LATER THIS MORNING THROUGH
EARLY AFTERNOON. WIND GUSTS UP TO 35 MPH ARE LIKELY. IN ADDITION A
PERIOD OF MODERATE RAIN IS LIKELY.

*  WIND ADVISORY.....SEE SFONPWMTR WWUS76 KMTR FOR DETAILS *

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

 DRY WEATHER IS FORECAST MONDAYBEFORE ANOTHER CHANCE OF RAIN
ARRIVES BY CHRISTMAS EVENING.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS PER STANDARD OPERATING PROCEDURES.