441
FXUS66 KMTR 112046
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
ISSUED BY NATIONAL WEATHER SERVICE EUREKA CA
146 PM PDT THU SEP 11 2025
..NEW AVIATION
KEY MESSAGES
UPDATED AT 1204 PM PDT THU SEP 11 2025
- SLIGHT (15-25%) CHANCE FOR SHOWERS IN THE NORTH BAY THURSDAY
AFTERNOON
- DRIER AND SLIGHTLY WARMER WEATHER FRIDAY AND SATURDAY, MUCH
WARMER EARLY NEXT WEEK.
SHORT TERM
ISSUED AT 1204 PM PDT THU SEP 11 2025
(THIS EVENING THROUGH FRIDAY)
SATELLITE IMAGERY THIS AFTERNOON DEPICTS LINGERING STRATUS IN THE
CENTRAL PART OF THE BAY AREA AND THE HIGHER ELEVATIONS OF THE SANTA
CRUZ MOUNTAINS AND THE NORTHERN SANTA LUCIA RANGE. MEANWHILE,
CUMULUS CLOUDS ARE STARTING TO POP UP ACROSS THE INTERIOR MOUNTAINS
FROM THE MAYACAMAS OF SONOMA AND NAPA COUNTIES THROUGH THE MOUNTAINS
AT THE EASTERN EDGE OF SANTA CLARA COUNTY, DOWN TO THE AREA NEAR AND
SOUTH OF SAN BENITO MOUNTAIN AND ALONG THE EASTERN EDGE OF MONTEREY
COUNTY. THE LATEST FORECAST UPDATE KEEPS A SLIGHT CHANCE FOR SHOWERS
(15-25% PROBABILITY) ACROSS THE NORTHERN AND CENTRAL PARTS OF SONOMA
AND NAPA COUNTY THROUGH THE AFTERNOON, BUT MORE INTENSE SHOWERS AND
THUNDERSTORMS WILL BE LIMITED TO THE NORTHERN COAST RANGES AND THE
SIERRA NEVADA RANGE. FOR THE REST OF THE REGION, RAIN IS NOT
EXPECTED, ALTHOUGH MUGGY CONDITIONS WILL LINGER THROUGH THE DAY.
HIGH TEMPERATURES TODAY WILL HOVER IN THE MIDDLE 70S TO THE LOWER
80S INLAND, UP TO THE MIDDLE 80S IN THE WARMEST SPOTS OF SOUTHERN
MONTEREY COUNTY, THE UPPER 60S TO THE MIDDLE 70S ALONG THE BAYS, AND
THE MIDDLE TO UPPER 60S ALONG THE PACIFIC COAST.
TONIGHT THROUGH FRIDAY, THE UPPER LEVEL LOW THAT ENABLES THE
CONVECTIVELY-DRIVEN SHOWERS WILL DIMINISH AND MOVE OFF TO THE EAST,
WITH A RIDGE SETTING UP BEHIND THE LOW PRESSURE SYSTEM. THIS WILL
SHUT OFF OUR RAIN CHANCES FOR THE REST OF THE WEEK AND CONTRIBUTE TO
WARMING TEMPERATURES AND DRIER HUMIDITIES. HIGHS IN THE INLAND
VALLEYS WILL RISE TO THE UPPER 70S TO THE MIDDLE 80S, AND UP TO THE
UPPER 80S IN THE WARMEST LOCATIONS. THE REST OF THE REGION REMAINS
RELATIVELY STABLE.
LONG TERM
ISSUED AT 1204 PM PDT THU SEP 11 2025
(FRIDAY NIGHT THROUGH NEXT WEDNESDAY)
CONDITIONS REMAIN DOMINATED BY THE NARROW BUT RATHER STOUT RIDGE ON
SATURDAY, BEFORE AN UPPER LEVEL TROUGH COMES IN FROM THE EASTERN
NORTH PACIFIC TO ERODE THE RIDGE ON SUNDAY. EARLIER FORECASTS HAD A
SLIGHT COOLDOWN AND A CHANCE FOR LIGHT RAIN IN THE BAY AREA ON
SUNDAY, BUT THE LATEST MODEL FORECASTS SHOW THAT THE TROUGH
INFLUENCE WILL NOT EXTEND AS FAR DOWN INTO THE STATE AS EARLIER
FORECASTS HAD INDICATED, RATHER KEEPING THE FLOW ZONAL AND THE BULK
OF THE TROUGH INFLUENCE IN THE PACIFIC NORTHWEST. THUS, WE ARE NO
LONGER EXPECTING ANY RAIN NOR MUCH OF A COOLDOWN ON SUNDAY. HEADING
INTO THE EARLY PART OF NEXT WEEK, RIDGING WILL START TO RETURN TO
THE REGION, WITH A UPPER LEVEL TROUGH OVER THE NORTHERN ROCKIES, AND
THE TEMPERATURES SHOULD SHOOT UP ABOVE SEASONAL AVERAGES. BY THE
MIDDLE OF NEXT WEEK, HIGHS WILL RANGE FROM THE UPPER 80S TO THE
MIDDLE 90S IN THE INLAND VALLEYS, AROUND 5 TO 12 DEGREES ABOVE
SEASONAL AVERAGES, WITH HIGHS IN THE UPPER 70S TO THE MIDDLE 80S
NEAR THE BAYS, AND EVEN THE PACIFIC COAST WARMING INTO THE LOWER
70S.
AVIATION
(18Z TAFS)
ISSUED AT 141 PM PDT THU SEP 11 2025
MVFR/VFR CONDITIONS ACROSS THE REGION, WITH MVFR CEILINGS TAKING A
COUPLE HOURS LONGER THAN EXPECTED TO CLEAR AT SFO AND OAK.
ONSHORE WINDS WILL INCREASE THIS AFTERNOON BEFORE DIMINISHING
AFTER SUNSET AND MORE SO INTO FRIDAY MORNING. THERE IS MODERATE TO
HIGH CONFIDENCE FOR MVFR CEILINGS TO RETURN THIS EVENING,
POTENTIALLY LOWERING TO IFR EARLY FRIDAY MORNING ACROSS THE
MONTEREY BAY TERMINALS. CEILINGS ARE FORECAST TO LIFT BY FRIDAY
AFTERNOON TO VFR WITH INCREASING ONSHORE WINDS.
VICINITY OF SFO...MVFR CEILINGS TAKING A COUPLE HOURS LONGER TO
SCATTER, PERHAPS 22-23Z OR EVEN A BIT LATER. EXPECTED TO RETURN
TO VFR BY 00Z WITH INCREASING ONSHORE WINDS. MODERATE TO HIGH
CONFIDENCE FOR MVFR CEILINGS TO RETURN LATE THIS EVENING AND
PERSIST THROUGH THE NIGHT. THERE IS LOW CONFIDENCE FOR SUB-MVFR
CEILINGS EARLY FRIDAY MORNING BEFORE CEILINGS LIFT TO VFR BY
FRIDAY AFTERNOON. ONSHORE WINDS INCREASE FRIDAY AFTERNOON.
SFO BRIDGE APPROACH...SIMILAR TO SFO.
MONTEREY BAY TERMINALS...HIGH CONFIDENCE FOR VFR CONDITIONS TO
RETURN TO THE REGION BY THIS AFTERNOON AND PERSIST THROUGH LATE
AFTERNOON OR EARLY EVENING. THEN, HIGH CONFIDENCE FOR MVFR CEILINGS
TO RETURN AND POTENTIALLY LOWER TO IFR EARLY FRIDAY MORNING.
MODERATE CONFIDENCE IN TIMING OF TRANSITION FROM MVFR TO IFR
OVERNIGHT TONIGHT INTO FRIDAY MORNING.
VICINITY OF SFO...
SFO BRIDGE APPROACH...
MONTEREY BAY TERMINALS...
MARINE
(TODAY THROUGH TUESDAY)
ISSUED AT 834 AM PDT THU SEP 11 2025
NORTHWEST WINDS INCREASE BEGINNING THURSDAY, BECOMING MODERATE TO
FRESH ACROSS THE MAJORITY OF THE COASTAL WATERS. LOCALIZED STRONG
GUSTS ARE POSSIBLE ACROSS THE NORTHERN OUTER WATERS. MODERATE TO
ROUGH SEAS DEVELOP FRIDAY AND PERSIST INTO NEXT WEEK. CONDITIONS
TEMPORARILY IMPROVE SATURDAY, AS WINDS DECREASE AND SEAS EASE,
BEFORE ANOTHER ROUND OF FRESH TO STRONG NW WINDS RETURNS SUNDAY
INTO NEXT WEEK WITH THE STRONGEST WINDS LOCATED ACROSS THE FAR
NORTHERN OUTER WATERS.
MTR WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...NONE.
SHORT TERM...DIALH
LONG TERM....DIALH
AVIATION...MHEINLEIN/RGASS
MARINE...RGASS
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