Issued by NWS San Francisco Bay Area, CA
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000 FXUS66 KMTR 220050 AFDMTR AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA CA 224 PM PST SAT NOV 21 2009 .DISCUSSION...AS OF 2:24 PM PST SATURDAY...CLEAR SKIES ARE BEING REPORTED ACROSS THE AREA THIS AFTERNOON. SO FAR AFTERNOON TEMPERATURES HAVE MADE IT INTO THE MID TO LOWER 50S WHICH IS WITHIN 2 TO 3 DEGREES OF YESTERDAY AFTERNOONS HIGH TEMPERATURES. THE LATEST VISIBLE SATELLITE IMAGE DOES SHOW CLEAR SKIES ACROSS THE CWA. HOWEVER...IT ALSO IS SHOWING A LARGE AREA OF CLOUDS MOVING TOWARDS NORTHERN CALIFORNIA. THIS LARGE AREA OF CLOUDS IS ASSOCIATED WITH A LOW PRESSURE SYSTEM CURRENTLY IN THE GULF OF ALASKA. A COLD FRONT RESULTING FROM THE PREVIOUSLY MENTIONED TROUGH OF LOW PRESSURE WILL SLIDE ACROSS THE NORTHBAY LATE TONIGHT AND WILL BRING WITH IT A SLIGHT CHANCE OF RAIN AND SOME ADDED CLOUD COVER. THE ADDED CLOUD COVER WILL KEEP THE NORTH BAY VALLEYS A FEW DEGREES WARMER THAN LAST NIGHT. TEMPERATURES ARE EXPECTED TO WARM UP A BIT THIS WEEK WITH THE RIDGE OF HIGH PRESSURE PUSHING 500 MB HEIGHTS TO 578 DM MONDAY AFTERNOON. THIS WILL RESULT IN TEMPERATURES WARMING TO MID 60S MONDAY AND POSSIBLY THE LOW 70S BY TUESDAY. THE WARMEST TEMPERATURES WILL MOST LIKELY BE IN THE SOUTHERN SALINAS VALLEY WITH KING CITY REACHING 72 DEGREES BY MID WEEK. THANKSGIVING DAY LOOKS TO BE MOSTLY DRY AND PLEASANT. HOWEVER...THE 1200 UTC ECMWF AND GFS MODELS DO BEGIN TO DIVERGE ON THEIR SOLUTIONS BY THURSDAY. THE ECMWF INSISTS ON DROPPING A TROUGH OF LOW PRESSURE ACROSS NORTHERN CALIFORNIA RESULTING IN A SLIGHT CHANCE OF PRECIPITATION FOR THE NORTH BAY AREA. MEANWHILE THE OPERATIONAL GFS IS SLOWER WITH THIS FEATURE AND APPEARS TO LIFT THE TROUGH NORTHWARD INTO BC SPARING THE AREA OF PRECIPITATION THANKSGIVING DAY AND INTO THE HOLIDAY WEEKEND. && .AVIATION...AS OF 4:30 PM PST SATURDAY...THE TAIL END OF A FRONTAL SYSTEM WILL BRING SOME LOWER CLOUDS INTO THE SFO BAY AREA LATE TONIGHT WELL AFTER THE AIRPORT EVENING RUSH HOUR. BASES OF THE CEILINGS ARE EXPECTED TO BE 2500-3000 FEET BUT CONFIDENCE IS LOW. VICINITY OF KSFO...VFR CONDITIONS THROUGH THE AIRPORT EVENING RUSH HOUR. SOME CEILINGS AT 2500-3000 FEET WILL MOVE IN AFTER MIDNIGHT. KSFO BRIDGE APPROACH...SAME AS KSFO. MONTEREY BAY TERMINALS...VFR CONDITIONS THROUGH SUNDAY. && .MTR WATCHES/WARNINGS/ADVISORIES... .TNGT...SCA...PT PINOS TO PT PIEDRAS BLANCAS TO 10 NM SCA...PIGEON PT TO PT PIEDRAS BLANCAS 10 TO 60 NM $$ PUBLIC FORECAST: LARRY AVIATION/MARINE: SSA/W PI NWS ON THE WEB AT WEATHER.GOV/SANFRANCISCO
