Flash Flood Warning 6, NWS San Francisco Bay Area, CA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
453 AM PST THU DEC 11 2014

...STRONG FRONT TO MOVE THROUGH THE BAY AREA TODAY...

.SYNOPSIS...HEAVY RAIN IN THE NORTH BAY THIS MORNING WILL WORK ITS
WAY THROUGH THE BAY AREA THROUGH MIDDAY AND EARLY AFTERNOON BEFORE
REACHING THE MONTEREY BAY REGION LATE THIS AFTERNOON/EARLY
EVENING. STRONG SOUTHERLY WINDS WILL ACCOMPANY THE FRONTAL PASSAGE
AND THEN SHIFT WEST BY THIS EVENING. SHOWERS AND POSSIBLE
THUNDERSTORMS WILL LINGER OVERNIGHT THROUGH FRIDAY AFTERNOON. DRY
WEATHER RETURNS THIS WEEKEND BEFORE ANOTHER CHANCE OF LIGHT RAIN
BY SUNDAY NIGHT INTO MONDAY.

&&

.DISCUSSION...AS OF 4:23 AM PST THURSDAY...WILL TRY AND BE CONCISE
AND FOCUS ON HEADLINES. THE FRONT HAS STALLED MOST OF THE NIGHT IN
THE NORTH BAY WITH ONLY 0.01 SO FAR IN THE CITY WHILE THE VENADO
GAGE ON THE SONOMA COAST IS NOW UP TO 4.12 INCHES. OTHER NOTABLE
RAIN TOTALS SO FAR INCLUDE 3.41 AT HAWKEYE (NORTHERN SONOMA) AND 2.48 AT
ANGWIN (NORTHERN NAPA). THE 06Z NAM CAME IN LAST NIGHT AND SHOWED
THE BULLS-EYE OF PRECIP OVER NORTHERN SONOMA AND SOUTHERN MENDOCINO
AND THAT SEEMS TO BE VERIFYING RIGHT NOW. THOSE IN THE BAY AREA
THAT ARE AWAITING MORNING RAINFALL JUST NEED TO BE PATIENT...THE
FRONT IS ON ITS WAY. HAVE ISSUED AN URBAN AND SMALL STREAM FLOOD
ADVISORY FOR THE 3 NORTH BAY COUNTIES FOR THIS MORNING TO COVER
THE COPIOUS RAINFALL THAT IS FALLING UP THERE. OTHER MAIN CONCERN
IS THE REACTION OF THE MAIN STEM RIVERS INCLUDING THE RUSSIAN AND
NAPA. WE RECEIVED NEW DATA AROUND 3 AM FROM THE RFC THAT SHOWS
SOME VERY IMPRESSIVE RISES. THE NAPA RIVER AT NAPA COULD REACH
FLOOD STAGE BY LATE THIS AFTERNOON SO THE FLASH FLOOD WATCH WILL
STAY IN PLACE. AFTER COORDINATING WITH HYDROLOGISTS WILL WAIT
UNTIL 9 AM MODEL SIMULATIONS BEFORE ISSUING ANY STATEMENTS ON THE
RUSSIAN OR NAPA. ANY QUICK RISES BY TONIGHT SHOULD BE FOLLOWED BY
RAPID FALLS AS WELL.

THE HEAVY RAIN WILL MARCH SOUTHWARD THROUGH THE BAY AREA LATER THIS
MORNING AND INTO THE EARLY AFTERNOON HOURS....FINALLY REACHING THE
MONTEREY BAY REGION LATE THIS AFTERNOON AND EARLY EVENING. THE
HEAVY RAIN WILL PRODUCE URBAN AND SMALL STREAM FLOODING ISSUES AND
THE FLASH FLOOD WATCH REMAINS IN EFFECT TODAY. HIGH WIND WARNING
WILL STAY IN PLACE AS WELL WITH VERY STRONG SOUTH WIND GUSTS TO 50
MPH AHEAD OF AND JUST BEHIND THE FRONTAL PASSAGE. WINDS WILL
QUICKLY EASE BEHIND THE FRONT THIS EVENING AND THE WARNING WILL
LIKELY BE ABLE TO BE DOWNGRADED BY THIS EVENING.

HIGH SURF ADVISORY REMAINS IN EFFECT AS WELL AND THE COASTAL BUOYS
ARE ALREADY REPORTING SEA HEIGHTS TO 16 FEET.

WERE ALSO MONITORING T-STORM POTENTIAL AND SPC HAS HIGHLIGHTED OUR
AREA FOR A MARGINAL THREAT. MAIN CONCERN IS ACTUALLY OVER THE
OCEAN WHERE THE WARM SSTS WILL HELP DESTABILIZE THINGS BEHIND THE
FRONT AS SOME OF THE COOLER AIR ALOFT ARRIVES.

STEADY RAIN WILL QUICKLY END BEHIND THE FRONT AND SHOWERS WILL
LINGER OVERNIGHT THROUGH FRIDAY EVENING. SATURDAY LOOKS
REAL NICE WITH HIGH PRESSURE BUILDING.

NEXT FRONT ARRIVES SUNDAY EVENING SO THE DAYLIGHT HOURS OF SUNDAY
LOOK GOOD. THE SUNDAY NIGHT INTO MONDAY RAIN LOOKS LIGHT TO
MODERATE WITH TOTALS FROM 0.25-0.75 FOR THE GREATER BAY AREA. A
NICE WINTER SOAKING. SHOWER THREAT TO CONTINUE AT LEAST THROUGH
TUESDAY WITH HINTS OF ANOTHER WEAK TO MODERATE STORM TOWARDS THE
SECOND HALF OF NEXT WEEK.

.&&

AVIATION...AS OF 4:45 AM PST THURSDAY... A POWERFUL PACIFIC CYCLONE
AND THE ASSOCIATED SURFACE FRONT WILL SIGNIFICANTLY IMPACT AVIATION
OPERATIONS ACROSS NORTHERN CALIFORNIA TODAY. EXPECT NUMEROUS AIRLINE
DELAYS/CANCELLATIONS THROUGH TODAY POSSIBLY CASCADING INTO THE
EVENING. DUE TO THE HIGHLY ENERGETIC NATURE OF THIS SYSTEM...
WINDS AND PRECIPITATION WILL BE SIGNIFICANT AND PRIMARILY PACKED
ALONG THE STEEP BOUNDARY. SUSTAINED SOUTH-SOUTHEAST WINDS AHEAD
OF THE FRONT WILL RANGE FROM 25 TO 35 KTS WITH A MAJORITY OF
GUSTS UP TO 45 KTS. LOCALIZED GUSTS IN FAVORED TOPOGRAPHY... ALONG
THE COAST AND OVER RIDGES...COULD EXCEED 60 KTS. CIGS WILL
INITIALLY BE BORDERLINE MVFR/VFR AHEAD OF THE FRONT BUT
DETERIORATE TO BORDERLINE MVFR/IFR IN FRONTAL/POST FRONTAL
ENVIRONMENT. WET RUNWAYS AND GUSTY SOUTH WINDS WILL PUSH MANY
AIRCRAFT OUT OF TOLERANCE FOR LANDING. RAIN WILL BE INITIALLY BE
MODERATE BUT BECOME HEAVY CLOSER TO FRONTAL BOUNDARY. IN THE POST
FRONTAL ENVIRONMENT THE WINDS WILL SHIFT AND WEAKEN HOWEVER
SHOWERS AND THUNDERSTORMS WILL THEN BECOME THE PRIME FOCUS AND
SOME TS BECOME SEVERE.

VICINITY OF KSFO...FRONTAL BOUNDARY WILL APPROACH THE VICINITY
WITHIN THE NEXT HOUR. AIRPORT WEATHER WARNING FOR STRONG AND GUSTY
S-SE WINDS VALID THROUGH 4 PM PST TODAY. GUSTS POTENTIAL UP TO
45 KNOTS...BUT WOULD NOT BE SURPRISED IF A FEW GUSTS GET CLOSER TO
60 KNOTS NEAR FRONTAL PASSAGE EARLY THURSDAY.

KSFO BRIDGE APPROACH...ADVERSE WEATHER SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...GUSTY BUT OTHERWISE VFR CONDITIONS
THROUGH THE EARLY MORNING. CIGS DETERIORATE TO MVFR BTWN 14-15Z
THU AS SYSTEM APPROACHES. WIND AND RAIN GRADUALLY INCREASE INTO
MIDDAY.

&&

&&

.MARINE...AS OF 04:26 AM PST THURSDAY...ONE OF THE STRONGEST
PACIFIC CYCLONES IN YEARS HAS ENTERED THE COASTAL WATERS AND WILL
CONTINUE TO BRING UNFAVORABLE MARITIME CONDITIONS THROUGH FRIDAY.
HAZARDOUS SEA CONDITIONS WILL DEVELOP WITH DANGEROUS SURF... LARGE
SWELL... THUNDERSTORMS... AND GALE FORCE WINDS WITH OCCASIONAL
STORM FORCE GUSTS. GUSTS WILL BE STRONGEST WITHIN A FEW HOUR SPAN
AHEAD OF THE FRONTAL PASSAGE.  WATERSPOUTS ARE ALSO A SLIGHT
POSSIBILITY. MARINERS VENTURING ON OPEN WATERS TODAY AND TONIGHT
ARE URGED TO USE EXTREME CAUTION AND CHECK THE LATEST CONDITIONS
BEFORE DEPARTING. CONDITIONS WILL IMPROVE ON FRIDAY AS THE STORM
EXITS THE REGION.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...HIGH WIND WARNING...ENTIRE SF AND MONTEREY BAY REGION
             FLASH FLOOD WATCH...ENTIRE SF AND MONTEREY BAY REGION
             HIGH SURF ADVISORY...COASTLINE FROM SONOMA TO BIG SUR
             GLW...SF BAY SOUTH OF THE BAY BRIDGE UNTIL 3 PM
             GLW...MONTEREY BAY UNTIL 3 PM
             GLW...PT ARENA TO PT REYES 0-10 NM UNTIL 3 PM
             GLW...PT REYES TO PIGEON PT 0-10 NM UNTIL 3 PM
             GLW...PIGEON PT TO PT PINOS 0-10 NM UNTIL 3 PM
             GLW...PT ARENA TO PT REYES 10-60 NM UNTIL 3 PM
             GLW...PT REYES TO PIGEON PT 10-60 NM UNTIL 3 PM
             GLW...PIGEON PT TO PT PINOS 10-60 NM UNTIL 3 PM
             GLW...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM
             GLW...PT PINOS TO PT PIEDRAS BLANCAS 10-60 NM
             SCA...ROUGH BAR ADVISORY FOR SF BAR
             SRW...SF BAY NORTH OF THE BAY BRIDGE UNTIL 3 PM

&&

PUBLIC FORECAST: RWW
AVIATION/MARINE: DRP

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
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HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
542 AM PST THU DEC 11 2014

CAZ006-505>513-516>518-528>530-120100-
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-
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 PARK-
NORTHERN SALINAS VALLEY...HOLLISTER VALLEY...AND CARMEL VALLEY-
NORTHERN MONTEREY BAY-SOUTHERN MONTEREY BAY AND BIG SUR COAST-
542 AM PST THU DEC 11 2014

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

.DAY ONE...THURSDAY AND THURSDAY NIGHT

A POWERFUL PACIFIC STORM SYSTEM WILL BRING HEAVY RAIN AND THE
POTENTIAL FOR STRONG DAMAGING WINDS THROUGH THURSDAY EVENING.

* HIGH WIND WARNING IN EFFECT FOR THE ENTIRE REGION *

* FLASH FLOOD WATCH IN EFFECT FOR THE ENTIRE REGION *

* HIGH SURF ADVISORY ALONG THE COAST *

* FOR A DETAILED VIEW OF THE HAZARDS...PLEASE VISIT
  HTTP://WWW.WEATHER.GOV/MONTEREY/HAZARDS

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

SHOWERS AND ISOLATED THUNDERSTORMS FRIDAY. DRY WEATHER RETURNS
SATURDAY THROUGH THE DAYLIGHT HOURS OF SUNDAY. LIGHT TO MODERATE
RAIN RETURNS SUNDAY NIGHT INTO MONDAY WITH SHOWERS THROUGH TUESDAY.

.SPOTTER INFORMATION STATEMENT...

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

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
732 AM PST THU DEC 11 2014

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0711 AM     FLOOD            1 NW LARKFIELD-WIKIUP   38.53N 122.77W
12/11/2014                   SONOMA             CA   LAW ENFORCEMENT

            ROADWAY FLOODING...STANDING WATER

&&

MMEHLE

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
737 AM PST THU DEC 11 2014

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0724 AM     DEBRIS FLOW      4 NW BOYES HOT SPRINGS  38.36N 122.53W
12/11/2014                   SONOMA             CA   LAW ENFORCEMENT

            MUDSLIDE PARTIALLY BLOCKING ROAD NB SIDE

0723 AM     FLOOD            1 S NAPA                38.28N 122.30W
12/11/2014                   NAPA               CA   LAW ENFORCEMENT

            WATER ACROSS ALL LANES

&&

MMEHLE

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
748 AM PST THU DEC 11 2014

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0742 AM     HEAVY RAIN       NE SAN FRANCISCO        37.78N 122.41W
12/11/2014  M1.68 INCH       SAN FRANCISCO      CA   TRAINED SPOTTER

            730 AM TO 740 AM

&&

MMEHLE

PRELIMINARY LOCAL STORM REPORT...CORRECTED
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
749 AM PST THU DEC 11 2014

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0742 AM     HEAVY RAIN       NE SAN FRANCISCO        37.78N 122.41W
12/11/2014  M0.00 INCH       SAN FRANCISCO      CA   TRAINED SPOTTER

            1.68 IN/HR RAINFALL RATE 730 AM TO 740 AM

&&

MMEHLE

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
753 AM PST THU DEC 11 2014

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0744 AM     NON-TSTM WND GST MT. HAMILTON            37.34N 121.64W
12/11/2014  M83.00 MPH       SANTA CLARA        CA   MESONET

            MEASURED AT LICK OBSERVATORY ELEVATION 4200 FEET

&&

JOHNSON

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
755 AM PST THU DEC 11 2014

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0750 AM     FLOOD            5 NW BURLINGAME         37.64N 122.44W
12/11/2014                   SAN MATEO          CA   LAW ENFORCEMENT

            ALL LANES FLOODED

&&

MMEHLE