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AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
949 AM PST SUN DEC 21 2014

.SYNOPSIS...LIGHT RAIN AND DRIZZLE WILL DIMINISH THIS MORNING AS
HIGH PRESSURE BUILDS OVER THE EASTERN PACIFIC. HIGHER THAN AVERAGE
TIDES WILL RESULT IN MINOR COASTAL FLOODING OVER THE NEXT SEVERAL
DAYS. TEMPERATURES WARM THROUGH MIDWEEK BEFORE A STORM BRUSHING
THE AREA BRINGS TEMPS BACK DOWN TO SEASONAL NORMALS.

&&

.DISCUSSION...AS OF 9:00 AM PST SUNDAY...ALTHOUGH THE RADAR SHOWS
VIRTUALLY NO ECHOES OF NOTE THIS MORNING QUITE A FEW GAUGES ARE
STILL REPORTING TIPS EVEN IN THE PAST HOUR. MOST LIKELY THE RADAR
BEAM IS OVERSHOOTING THE BULK OF THE RAIN AND SPOTS ARE SEEING
EITHER DRIZZLE OR VERY LIGHT RAINFALL. PRECIPITATION SHOULD
CONTINUE TO BE ON THE DECREASE THROUGH THE DAY AS A RIDGE OF HIGH
PRESSURE STARTS TO BUILD INTO OUR AREA. ALSO STARTING TO SEE SOME
POCKETS OF MOSTLY SUNNY CONDITIONS OVER THE SOUTHERN THIRD OF THE
CWA. WILL DO A MINOR UPDATE THIS MORNING TO REFLECT THE SKY
CONDITIONS.

REST OF THE FORECAST APPEARS RIGHT ON TRACK WITH THE MAIN STORY
BEING THE MINOR WARMING TREND ALONG WITH DRIER CONDITIONS. 12Z
MODELS COMING IN NOW KEEP ANY MAJOR STORMS WELL OUT OF OUR AREA
FOR THE REMAINDER OF THE WEEK.

.PREVIOUS DISCUSSION...LIGHT RAIN AND DRIZZLE CONTINUE THIS
MORNING...GENERALLY MEASURING JUST A FEW HUNDREDTHS. VERTICAL
PROFILING RADAR CONFIRMS THAT PRECIP IS CONFINED TO THE FIRST
SEVERAL THOUSAND FEET OF THE ATMOSPHERE AND IS THUS UNDER THE
BEAM OF THE KMUX WSR-88D RADAR. WARM AIR ADVECTION AND ABUNDANT
MOISTURE WILL RESULT IN A FEW MORE HUNDREDTHS OVER THE NEXT
SEVERAL HOURS HOWEVER IT WILL TAPER OFF THIS MORNING AS HIGH
PRESSURE BUILDS JUST OFF THE COAST. THE LOW LEVEL MOISTURE WILL
REMAIN...KEEPING OVERNIGHT LOWS 10 TO 15 DEGREES ABOVE NORMAL.
PATCHY FOG HAS DEVELOPED ALONG THE COAST AND IN THE NORTH BAY
THIS MORNING AND WILL BECOME MORE PREVALENT IN THE COMING NIGHTS.

MINOR COASTAL FLOODING WILL BE POSSIBLE ALONG THE COASTLINE AND
THE BAY SHORE FOR THE NEXT SEVERAL DAYS. PERIGEAN SPRING
TIDES...ALSO CALLED KING TIDES...WILL CAUSE INUNDATION OF LOW
LYING COASTAL AREAS. THESE HIGHER THAN AVERAGE MORNING HIGH TIDES
WILL PEAK MONDAY. SEE THE COASTAL FLOOD ADVISORY MESSAGE FOR MORE
INFORMATION.

THE RIDGE CURRENTLY BUILDING OVER THE EASTERN PACIFIC IS SET TO
HAVE ITS AXIS RUN SW TO NE ACROSS THE WESTERN STATES...DEFLECTING
STORM ACTIVITY WELL TO THE NORTH. THIS WILL KEEP THE AREA DRY
THROUGH AT LEAST WEDNESDAY MORNING. DAYTIME HIGH TEMPERATURES
WARM INTO THE UPPER 60S TO LOW 70S ACROSS THE AREA.

BY MIDWEEK THE RIDGE BREAKS DOWN OVER CALIFORNIA AND THE AXIS
SHIFTS WEST ALLOWING A SHORTWAVE TO DIG INTO THE GREAT BASIN.
THIS INSIDE SLIDER WILL MOVE THROUGH THE PACIFIC NORTHWEST AND SE
TOWARD NEVADA AND UTAH. THE 00Z RUNS OF THE GFS ECMWF AND GEM ALL
AGREE ON THE SYSTEM JUST BRUSHING BY THE AREA AND GEFS ENSEMBLES
HAVE JUST TEN PERCENT PROBABILITY OF A TENTH OF AN INCH OF PRECIP
AT SFO. THE EXACT POSITION OF THE SHORTWAVE WILL DETERMINE RAIN
CHANCES AND FOR NOW HAVE LEFT A SLIGHT CHANCE CHRISTMAS
EVE...MOSTLY IN THE NORTH BAY. THE MORE CERTAIN IMPACT OF THIS
SYSTEM WILL BE TEMPERATURES COOLING BACK DOWN TO NEAR NORMAL FOR
LATE DECEMBER.

AFTER CHRISTMAS TEMPERATURES LOOK TO REMAIN SEASONABLE INTO NEXT
WEEK. THE GLOBAL MODELS ARE HINTING AT ANOTHER STORM SYSTEM
POSSIBLE IN THE LAST FEW DAYS OF 2014.

&&

.AVIATION...AS OF 9:45 AM PST SUNDAY...ABUNDANT LOW LEVEL MOISTURE
REMAINS IN PLACE ACROSS MUCH OF THE REGION AND HAS RESULTED LOW
CIGS OVER MOST TERMINALS THIS MORNING. EXPECTING CIGS TO LIFT
SLIGHTLY AND SCT OUT BRIEFLY DURING THE AFTERNOON HOURS...YET
PREVAILING MVFR CIGS MORE LIKELY TO PERSIST. CIGS AND VSBYS LOWER
AGAIN LATE THIS EVENING AND WILL PERSIST THROUGH MONDAY MORNING.

VICINITY OF KSFO...EXPECTING CIGS TO LIFT AND VSBYS TO IMPROVE
THROUGH 20Z...YET PREVAILING MVFR CIGS LIKELY THROUGH THE
AFTERNOON DESPITE A FEW BRIEF BREAKS. LIGHT WESTERLY WINDS.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...MVFR CIGS TO PERSIST THROUGH MUCH OF
THE DAY...DESPITE A FEW BRIEF BREAKS THIS AFTERNOON. WINDS WILL
GENERALLY REMAIN LIGHT.

&&

.MARINE...AS OF 9:00 AM PST SUNDAY...NORTHWEST WINDS WILL INCREASE
OVER THE SOUTHERN AND OUTER WATERS THIS AFTERNOON AND PERSIST
THROUGH MONDAY AS HIGH PRESSURE BUILDS OFF THE CALIFORNIA COAST.
WHILE LARGE SWELLS WILL CONTINUE TO DECREASE TODAY...KING TIDES
WILL IMPACT THE COAST AND INLAND BAYS OVER THE NEXT THREE DAYS.
KING TIDE IMPACTS FOR SEAFARING VESSELS WILL OCCUR PRIMARILY
DURING LOW TIDES...WITH THE POSSIBILITIES OF BOAT KEELS TOUCHING
HARBOR BOTTOM...STRONG CURRENTS IN HARBOR ENTRANCES...AND
ADDITIONAL BREAKING WAVES OVER OFFSHORE REEFS. 
&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...COASTAL FLOOD ADVISORY...ALL COASTAL AND BAY SHORE AREAS
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 10-60 NM FROM 3 PM
             SCA...ROUGH BAR ADVISORY FOR SF BAR
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM FROM 1 PM


&&

$$

PUBLIC FORECAST: BELL/AC
AVIATION/MARINE: RGASS

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