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

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS66 KMTR 211749 AFDMTR 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 VISIT US AT WEATHER.GOV/SANFRANCISCO FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSBAYAREA WWW.TWITTER.COM/NWSBAYAREA WWW.YOUTUBE.COM/NWSBAYAREA

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.