229 FXUS66 KMTR 221753 AFDMTR AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA CA 952 AM PST SUN NOV 22 2009 .DISCUSSION...AS OF 9:06 AM PDT SUNDAY...A TROUGH OF LOW PRESSURE IS MOVING THROUGH THE PACIFIC NORTH WEST SLIDING A COLD FRONT ACROSS NORTHERN CALIFORNIA. BEHIND THE COLD FRONT A RIDGE OF HIGH PRESSURE IS BUILDING OVER THE EASTERN PACIFIC. CURRENTLY ENERGY AND MOISTURE EMBEDDED WITHIN THE NORTHWEST FLOW OF THE DEVELOPING RIDGE IS PASSING OVER NORTHERN PORTIONS OF THE CWA BRINGING LIGHT RAIN TO NAPA AMD SONOMA COUNTIES. SO FAR KSTS HAS REPORTED A LITTLE MORE THAN A TENTH OF AN INCH OF RAIN OVER THE PAST 3 HOURS. THIS ENERGY SHOULD DISSIPATE BY THIS EVENING BRINGING AN END TO THE PRECIPITATION. DRY PLEASANT CONDITIONS ARE EXPECTED THROUGH THANKSGIVING AS THE DEVELOPING RIDGE OF HIGH PRESSURE REMAINS ANCHORED OVER THE WESTERN UNITED STATES. ALONG WITH THE HIGH PRESSURE ALOFT GENERALLY OFFSHORE FLOW WILL PREVAIL AT THE SURFACE LIMITING THE OCEANS INFLUENCE ON THE TEMPERATURES. THIS WILL RESULT IN AFTERNOON TEMPERATURES GENERALLY IN THE MID TO UPPER 60S WITH LOWER 70S EXPECTED IN SOUTHERN MONTEREY AND SAN BENITO COUNTIES. BY THURSDAY EVENING THE MODELS ARE STILL ADVERTISING A TROUGH OF LOW PRESSURE MOVING INTO THE PACIFIC NORTHWEST. THE 0000 UTC ECMWF AND 1200 UTC OPERATIONAL GFS APPEAR TO BE IN BETTER AGREEMENT WITH THIS FEATURE THAN THEY HAVE ON PAST MODEL RUNS. WITH THAT BEING SAID THE ECMWF IS STILL DEEPER THAN THE GFS SOLUTION. REGARDLESS IT LOOKS LIKE BOTH MODELS ARE TRENDING TOWARDS A DRIER FORECAST. && .AVIATION...AS OF 9:52 AM PST SUNDAY...A WEAK COLD FRONT IS PASSING THROUGH THE BAY AREA RIGHT NOW WITH LIGHT RAIN OCCURRING AT SFO. CEILINGS WILL CONTINUE TO BE IN THE MVFR RANGE UNTIL 22Z...THEN SCATTER OUT AS THE FRONT MOVES PAST. NORTH WIND FLOW WILL DEVELOP TONIGHT WHICH SHOULD ALLOW FOR SOME CLEARING. VICINITY OF KSFO...CIGS WILL CONTINUE IN THE 1800-2000 RANGE UNTIL ABOUT 20Z...THEN RAISE ABOVE 2000 FEET...SCATTERING OUT BY 22Z.LIGHT SOUTH TO SOUTHEAST WINDS 5 KT OR LESS EXPECTED DURING THE MORNING HOURS SWITCHING TO WEST LESS THAN 15 KT IN THE AFTERNOON. VICINITY SHOWERS MANY ACCOMPANY THE FROPA. KSFO BRIDGE APPROACH...SAME AS KSFO. MONTEREY BAY TERMINALS...VFR CONDITIONS TODAY. && .MTR WATCHES/WARNINGS/ADVISORIES... .TDA...NONE $$ PUBLIC FORECAST: LARRY AVIATION/MARINE: SSA NWS ON THE WEB AT WEATHER.GOV/SANFRANCISCO