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

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FXUS66 KMTR 250033
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
433 PM PST WED DEC 24 2014

...LOCALLY BLUSTERY CONDITIONS NEAR THE COAST AND IN THE HILLS TONIGHT
THROUGH CHRISTMAS MORNING...
...MUCH COOLER WEATHER BY CHRISTMAS DAY...

.SYNOPSIS...A COLD FRONT CONTINUES TO SPREAD LIGHT RAIN ACROSS THE
SAN FRANCISCO BAY AREA THIS AFTERNOON. THE COLD FRONT WILL
CONTINUE TO PUSH SOUTH THIS EVENING BRINGING LIGHT RAIN INTO THE
MONTEREY BAY AREA THIS EVENING. GUSTY NORTHWEST WINDS WILL
DEVELOP BEHIND THE COLD FRONT WITH LOCALLY STRONG AND GUSTY WINDS
ANTICIPATED ALONG THE COAST AND IN THE HILLS TONIGHT INTO
CHRISTMAS MORNING. OTHERWISE CHRISTMAS DAY WILL BE DRY AND COOL
WITH DRY WEATHER EXPECTED TO CONTINUE THROUGH NEXT WEEK. SOME OF
THE COLDEST TEMPERATURES SO FAR THIS SEASON ARE EXPECTED FOR SOME
INLAND VALLEYS THURSDAY NIGHT AND FRIDAY NIGHT.

&&

.DISCUSSION...AS OF 2:40 PM PST WEDNESDAY...KMUX DOPPLER RADAR IS
SHOWING A LINE OF SHOWERS ASSOCIATED WITH A COLD FRONT PASSING
OVER THE SAN FRANCISCO BAY AREA THIS AFTERNOON. THE COLD FRONT IS
EXPECTED TO SPREAD LIGHT RAIN SOUTH INTO MONTEREY BY THIS EVENING.
EXPECT COOL AND GUSTY NORTHWEST WINDS BEHIND THE COLD FRONT WITH
THE STRONGEST WINDS EXPECTED ALONG THE COAST AND ACROSS THE RIDGE
TOPS OVER NIGHT. BE SURE TO SECURE YOUR OUTDOOR CHRISTMAS
DECORATIONS AND TRASH CANS THIS EVENING.

ALONG WITH THE 1200Z ECMWF THE 1800Z GFS40 AND NAM12 HAVE
INITIALIZED WELL WITH THE CURRENT SYNOPTIC PATTERN AND REMAIN IN
GOOD AGREEMENT THROUGH THE NEXT 84 HOURS. ALL THREE MODELS
CONTINUE TO MOVE TODAY`S STORM SYSTEM OUT OUR AREA BY CHRISTMAS
MORNING...QUICKLY BUILDING IN A RIDGE OF HIGH PRESSURE BEHIND THE
DEPARTING STORM SYSTEM.

THE RIDGE OF HIGH PRESSURE WILL BRING DRY WEATHER TO THE AREA WITH
SEASONAL DAY TIME TEMPERATURES. THE DOWNSIDE IS THAT THE HIGH
PRESSURE WILL PROMOTE CLEAR SKIES WHICH WILL ALLOW FOR AMPLE
RADIATIVE COOLING WHICH IN TURN WILL RESULT IN COLD NEAR FREEZING
TEMPERATURES FOR MANY LOCATIONS AROUND THE FORECAST AREA BEGINNING
CHRISTMAS NIGHT AND LASTING THROUGH AT LEAST SATURDAY NIGHT. THE
COLDEST TEMPERATURES WILL OCCUR IN THE INLAND VALLEYS. AT THIS
POINT FRIDAY NIGHT LOOKS TO BE THE COLDEST NIGHT WITH NAPA
EXPECTED TO FALL TO AROUND 35...PLEASANTON 34...GILROY 33 AND KING
CITY 33.

&&

.AVIATION...AS OF 4:30 PM PST WEDNESDAY...FAST MOVING COLD FRONTAL
BAND PASSED BY THE NWS OFFICE IN MONTEREY WITH SOME LIGHT RAIN AND
GUSTY WINDS. KMUX RADAR IS NOT SHOWING MUCH REFLECTIVITIES ALONG
THIS PART OF THE COLD FRONT HERE AS THE RADAR BEAM AT 5900 FEET IS
OVER THE TOP OF THE PRECIPITATION. NARROW BAND OF MODERATE TO BRIEFLY
HEAVY RAIN SHOWERS EXTEND ENE TO NORTHERN SAN BENITO COUNTY. THE
COLD FRONT WILL CONTINUE TO PRESS SOUTHEASTWARD THIS EVENING WITH
RAPIDLY DRYING WEATHER BEHIND THE FRONTAL SYSTEM. GUSTY W-NW WINDS
WILL CONTINUE AT LEAST INTO THE EARLY EVENING HOURS BEFORE SURFACE
WIND DE-COUPLING BECOMES INCREASINGLY PROBABLE IN VALLEY LOCATIONS
AND LESS PROBABLE OVER THE HILLS AND MTNS. NOT LIKELY TO HAPPEN
THIS EVENING BUT WILL MONITOR FOR SLIGHT PROBABILITY OF LOW LEVEL
WIND SHEAR (LLWS) AT AREA TERMINALS. SUFFICIENT ATMOSPHERIC MIXING IS
FORECAST TONIGHT WHICH WILL PRECLUDE LATE NIGHT/EARLY MORNING FOG
DEVELOPMENT THAT IS DEPENDENT UPON LIGHT WINDS AND A STABLE AIR
MASS. GUSTY N-NW LOW LEVEL WINDS WILL CONTINUE THROUGH THURSDAY
AND THURSDAY NIGHT RESULTING IN CONTINUED DRY WEATHER AND VFR
CONDITIONS.

VICINITY OF KSFO...RECENT 5 MIN ASOS OBS FROM KSFO INDICATE PEAK
WEST WIND GUSTS TO 37 KNOTS. ISSUED AN AIRPORT WEATHER WARNING FOR
WINDS VALID TIL 04Z (8 PM PST). W-NW SURFACE TO LOW LEVEL WINDS
ARE LINKED WITH WIND GUSTS TO 37 KNOTS AND 39 KNOTS HALF MOON BAY
AND SAN FRANCISCO BUOYS RESPECTIVELY. WILL TAKE A FEW HOURS FOR
W-NW WIND TO VEER TO STRONGER NORTHERLY DIRECTION BY WHICH TIME
ANTICIPATE THE KSFO SURFACE WINDS TO TAPER OFF SOME.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...COLD FRONT IS SWEEPING BY HEADING
OFF TO THE SE AT QUICK PACE. CLEARING WILL MOVE INTO THE REGION
DURING THE EVENING. GUSTY W-NW WINDS WILL CONTINUE AT LEAST INTO
THE EARLY EVENING.

&&

.MARINE...AS OF 09:58 AM PST WEDNESDAY...A SWIFTLY APPROACHING
STORM WILL SWEEP ACROSS THE REGION LATER TODAY. THIS WILL RESULT
IN STRONG NORTH TO NORTHWEST WINDS OVER THE COASTAL WATERS LATE
THIS AFTERNOON AND INTO THURSDAY. SUSTAINED GALE FORCE WINDS WITH
OCCASIONAL STORM FORCE GUSTS ARE POSSIBLE OVER THE OUTER WATERS.
FOR THE COASTAL WATERS... EXPECT SMALL CRAFT WINDS WITH OCCASIONAL
GALE FORCE GUSTS.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...GLW...PT PINOS TO PT PIEDRAS BLANCAS 10-60 NM FROM 7 PM
             SCA...SF BAY NORTH OF THE BAY BRIDGE FROM 7 PM
             SCA...SF BAY SOUTH OF THE BAY BRIDGE FROM 7 PM
             SCA...PIGEON PT TO PT PINOS 0-10 NM FROM 7 PM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM FROM 7 PM
             GLW...PT ARENA TO PT REYES 10-60 NM
             GLW...PT REYES TO PIGEON PT 10-60 NM
             GLW...PIGEON PT TO PT PINOS 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...MONTEREY BAY FROM 7 PM UNTIL 4 AM

&&

$$

PUBLIC FORECAST: LARRY
AVIATION: CANEPA
MARINE: W PI

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