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

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000 FXUS66 KMTR 311153 AFDMTR AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA 353 AM PST SAT JAN 31 2015 .SYNOPSIS...DRY AND MILD CONDITIONS ARE EXPECTED TO CONTINUE THROUGH THE MIDDLE OF NEXT WEEK WITH RAIN CHANCES CONFINED TO FAR NORTHERN CALIFORNIA. TEMPERATURES WILL REMAIN SEVERAL DEGREES ABOVE NORMAL. THERE ARE INDICATIONS THAT RAIN MAY MOVE INTO THE AREA BY THE END OF NEXT WEEK. && .DISCUSSION...AS OF 3:45 AM PST SATURDAY...OFFSHORE SURFACE FLOW IS RESULTING IN MOSTLY CLEAR SKIES ACROSS THE NORTHERN HALF OF THE DISTRICT WITH MUCH LESS STRATUS OVER THE COASTAL WATERS FROM ABOUT THE MONTEREY BAY NORTHWARD. INLAND...THE ONLY AREAS WITH FOG FORMATION INCLUDE THE SALINAS VALLEY AND AROUND THE MONTEREY BAY...AND JUST NOW EXTENDING INTO THE SANTA CLARA VALLEY. SO FAR THE THE NORTH BAY VALLEYS ARE FOG-FREE...BUT SOME PATCHY FOG IS STILL POSSIBLE TO DEVELOP THERE EVEN WITH THE OFFSHORE FLOW. CURRENTLY SURFACE PRESSURE GRADIENTS ARE OFFSHORE WITH 8.1 MB FROM WMC TO SFO AND 4.3 FROM ACV TO SFO. THE OFFSHORE GRADIENTS ARE FORECAST TO PERSIST THROUGH TODAY THEN SWITCH TO ONSHORE ON SUNDAY. CURRENTLY NORTHERLY WINDS ARE STRONGEST IN THE NORTH BAY HILLS WHERE GUSTS IN THE 20S AND 30S ARE OCCURRING. WINDS ARE EXPECTED TO TAPER OFF LATER TODAY WHEN THE GRADIENTS BEGIN TO RELAX. HIGH TEMPERATURES ARE FORECAST TO BE IN THE MID 60S TO MID 70S TODAY...WARMER THAN YESTERDAY AND ABOVE NORMAL. SLIGHTLY COOLER TEMPS ARE EXPECTED ON SUNDAY AS THE SURFACE FLOW RETURNS TO ONSHORE. THE DRY WEATHER WILL CONTINUE THROUGH AT LEAST THE MIDDLE OF NEXT WEEK AS THE UPPER LEVEL RIDGE REMAINS ANCHORED OVER THE WEST. A SYSTEM PROGGED TO AFFECT THE PACIFIC NORTHWEST EARLY IN THE WEEK COULD BRING SOME RAIN TO THE EXTREME NORTHERN PART OF THE STATE BUT OUR DISTRICT IS EXPECTED TO REMAIN DRY. MEDIUM RANGE MODELS CONTINUE TO BRING RAIN CHANCES FAR ENOUGH SOUTH TO REACH OUR DISTRICT BY THE END OF NEXT WEEK. THERE CONTINUE TO BE DIFFERENCES IN MODEL SOLUTIONS REGARDING THIS POTENTIAL RAIN...BUT INDICATIONS ARE LOOKING MORE FAVORABLE TO FINALLY SEEING AT LEAST SOME RAINFALL ACROSS THE AREA BY NEXT WEEKEND. && .AVIATION...AS OF 3:53 AM PST SATURDAY...THE CURRENT IR SATELLITE FOG PRODUCT IS SHOWING CLEAR SKIES IN THE SAN FRANCISCO BAY AREA WITH STRATUS IN MONTEREY BAY STRETCHING SOUTH INTO THE SALINAS VALLEY. LOCAL SURFACE OBS ARE SHOWING LIGHT OFFSHORE FLOW AT THE SURFACE DUE TO A THERMAL TROUGH POSITIONED OVER CALIFORNIA. THE GENTLE OFFSHORE FLOW SHOULD BE SUFFICIENT ENOUGH TO MAINTAIN VFR IN THE SAN FRANCISCO BAY AREA THIS MORNING AND WILL AID IN THE MORNING BURN OFF FOR THE MONTEREY BAY AREA. VICINITY OF KSFO...VFR. GENERALLY LIGHT WINDS THIS MORNING WITH SEA BREEZE REACHING 5 TO 10 KT THIS AFTERNOON. CONFIDENCE HIGH. KSFO BRIDGE APPROACH...SIMILAR TO KSFO. MONTEREY BAY AREA TERMINALS...IFR CONDITIONS ARE ANTICIPATED TO BURN OFF BY 1600Z AT KMRY AND 1730Z AT KSNS. VFR IS THEN ANTICIPATED TO PREVAIL INTO THE EVENING HOURS. THE SEA BREEZE WILL REACH 5 TO 10 KT THIS AFTERNOON. & .MARINE...AS OF 02:39 AM PST SATURDAY...NORTHERLY WINDS WILL DECREASE THIS MORNING AS THE SURFACE PRESSURE GRADIENT WEAKENS. AS THE WINDS DECREASE THE SEA CONDITIONS WILL IMPROVE. LIGHT WINDS AND RELATIVELY GENTLE SEAS ARE THEN EXPECTED THROUGH MID WEEK. && .MTR WATCHES/WARNINGS/ADVISORIES... .TDAY...NONE. $$ PUBLIC FORECAST: SIMS AVIATION/MARINE: LARRY 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

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