161
FXUS66 KMTR 260548
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
948 PM PST TUE NOV 25 2025
..NEW AVIATION, MARINE
KEY MESSAGES
UPDATED AT 120 PM PST TUE NOV 25 2025
- DRY AND MILD CONDITIONS CONTINUE THROUGH THURSDAY
- COOLER TEMPERATURES FRIDAY AND INTO THE WEEKEND AS THE NEXT
SYSTEM APPROACHES
- GUSTY OFFSHORE WINDS ARE POSSIBLE BY THE END OF THE WEEKEND AND
INTO EARLY NEXT WEEK
UPDATE
ISSUED AT 851 PM PST TUE NOV 25 2025
AND HERE WE GO AGAIN. TEMPS ARE FALLING TO OR NEAR TO THE DEWPOINT
TEMP, WHICH MEANS THAT THE RELATIVE HUMIDITY IS AT OR APPROACHING
100%, WHICH MEANS SATURATION YIELDING HAZE OR FOG. IN ADDITION,
THE WINDS ARE VERY LIGHT. LOOKING AT OBSERVATIONS AROUND THE AREA
SANTA ROSA IS ALREADY REPORTING 2 SM, NAPA 1.5 SM, AND LIVERMORE 5
SM. WILL LIKELY DO A QUICK UPDATE TO THE FORECAST TO EXPAND THE
FOG FARTHER WEST. APART FROM THAT, THE FORECAST REMAINS ON TRACK
THIS EVENING.
SHORT TERM
ISSUED AT 120 PM PST TUE NOV 25 2025
(THIS EVENING THROUGH WEDNESDAY)
LOW CLOUDS PERSIST OVER THE NORTH BAY AND EAST BAY, YET ARE FORECAST
TO BEGIN CLEARING LATER THIS AFTERNOON. HOWEVER, IF THEY DO NOT,
TEMPERATURES WILL BE COOLER THAN CURRENTLY FORECAST BY UP TO 10
DEGREES. ELSEWHERE, TEMPERATURES ARE FORECAST TO REACH INTO THE 60S
ACROSS MOST INLAND AREAS WHILE THE IMMEDIATE COASTAL AREAS OF THE
NORTH BAY AND SAN FRANCISCO PENINSULA REMAIN IN THE MID-TO-UPPER
50S.
AS OFFSHORE FLOW PERSIST IN THE HIGHER ELEVATIONS ACROSS THE REGION,
THE MARINE LAYER REMAINS COMPRESSED. THUS, THERE IS GREATER
PROBABILITY FOR LESS COVERAGE OF FOG OVERNIGHT. HOWEVER, STILL
EXPECTING PATCHY TO AREAS OF DENSE FOG ACROSS THE NORTH BAY VALLEYS,
EAST BAY VALLEYS, AND THE SANTA CLARA VALLEY OVERNIGHT. TEMPERATURES
OVERNIGHT ARE FORECAST TO BE MOSTLY IN THE 40S WITH THE COLDEST
INTERIOR SPOTS POTENTIALLY LOWERING INTO THE UPPER 30S.
AS THE RIDGE AXIS SHIFTS EASTWARD INTO SOUTHERN CALIFORNIA,
TEMPERATURES WILL CONTINUE TO WARM ON WEDNESDAY. THIS IS WHEN WE ARE
EXPECTING TEMPERATURES ACROSS THE INTERIOR CENTRAL COAST, SANTA CRUZ
AREA, SOUTHERN SANTA CLARA AND HOLLISTER VALLEYS, AND FAR INLAND
NORTH BAY VALLEYS TO REACH OR EXCEED 70 DEGREES F. THESE
TEMPERATURES WILL BE UP TO 10 DEGREES ABOVE SEASONAL AVERAGES.
AGAIN, SIMILAR TO TODAY, AREAS THAT DO NOT SEE AFTERNOON SUNSHINE
WILL LIKELY BE A FEW TO SEVERAL DEGREES COOLER.
LONG TERM
ISSUED AT 120 PM PST TUE NOV 25 2025
(WEDNESDAY NIGHT THROUGH NEXT MONDAY)
ON THURSDAY, AN UPPER LEVEL TROUGH IS FORECAST TO APPROACH THE
PACIFIC NORTHWEST BRINING UNSETTLED WEATHER TO THAT AREA. LOCALLY,
WE ARE FORECAST TO SEE SIMILAR TEMPERATURES AS WEDNESDAY FOR DAYTIME
HIGHS. BY FRIDAY, THIS FEATURE WILL SHIFT INTO THE NORTHERN PART OF
THE INTERMOUNTAIN WEST, THUS COOLING TEMPERATURES TO NEAR SEASONAL
AVERAGES AS A WEAK, DRY BACK DOOR COLD FRONT SWEEPS ACROSS THE BAY
AREA AND CENTRAL COAST. A REINFORCING TROUGH WILL DROP OUT OF
BRITISH COLUMBIA AND ACT AS AN INSIDE SLIDER SETUP AS IN DROPS
SOUTHWARD ACROSS THE INTERMOUNTAIN WEST. THIS WOULD LEAD TO GUSTY
OFFSHORE WINDS ACROSS OUR REGION. HOWEVER, EXACT DETAILS REAMIN
DIFFICULT TO PIN DOWN AT THIS TIME AS THERE REMAINS UNCERTAINTY THIS
FAR OUT. BE SURE TO CHECK BACK AND KEEP UP-TO-DATE WITH THE LATEST
FORECAST INFORMATION.
AVIATION
(06Z TAFS)
ISSUED AT 948 PM PST TUE NOV 25 2025
FOG IS STARTING TO MAKE ITS WAY INTO THE NORTH BAY AND EAST BAY.
CONFIDENCE IS MODERATE TO HIGH IN FOG IMPACTING STS, APC, AND LVK
OVERNIGHT, MODERATE CONFIDENCE IT WILL REACH OAK, SJC, AND SNS, AND
LOW CONFIDENCE IN FOG REACHING SFO, HAF, AND MRY. STS AND APC HAVE
ALREADY REPORTED FOG WITH CAMERAS SHOWING FOG FILLING IN ACROSS THE
EAST BAY. CURRENT THINKING IS THAT IF SITES DO START TO DEVELOP FOG,
VISIBILITIES AND CEILING HEIGHTS WILL DROP RAPIDLY. WINDS STAY LIGHT
AND OFFSHORE OVERNIGHT BEFORE BECOMING MORE NORTHWESTERLY TO
NORTHERLY DURING THE DAY. LIGHT, OFFSHORE WINDS REDEVELOP OVERNIGHT
WITH POTENTIAL FOR FOG TO RETURN AGAIN.
VICINITY OF SFO...VFR THROUGH THE TAF PERIOD. CONFIDENCE IS LOW THAT
FOG WILL EXTEND ACROSS THE SF BAY TONIGHT AND REACH SFO. CURRENT
THINKING IS THAT FOG WILL NOT BE AS EXPANSIVE TONIGHT AS IT WAS LAST
NIGHT WITH FOG MORE LIMITED TO THE NORTH BAY AND INTERIOR EAST BAY.
WINDS STAY LIGHT AND OFFSHORE OVERNIGHT BEFORE MODERATE ONSHORE
WINDS RETURN DURING THE DAY. WINDS WEAKEN AND SHIFT OFFSHORE AGAIN
OVERNIGHT WITH GUIDANCE SUGGESTING SOME POTENTIAL FOR LOWER
VISIBILITIES AND CEILINGS TOMORROW NIGHT.
SFO BRIDGE APPROACH...SIMILAR TO SFO.
MONTEREY BAY TERMINALS...VFR AT MRY, VFR POTENTIALLY BECOMING IFR AT
SNS OVERNIGHT. FOR MRY - FOG IS NOT EXPECTED TO REACH THE TERMINAL
TONIGHT WITH WINDS REMAINING LIGHT AND GENERALLY OFFSHORE THROUGH
THE TAF PERIOD. FOR SNS - LEANED ON PERSISTENCE TO SHOW FOG
POTENTIAL FOR TOMORROW MORNING. THE KEY THING TO WATCH FOR IS IF FOG
WILL FILL IN ACROSS THE SOUTHERN SALINAS VALLEY AND GRADUALLY FLOW
SOUTH TO NORTH. SNS LOOKS TO DEVELOP MODERATE SE DRAINAGE WINDS
EARLY TOMORROW MORNING WHICH COULD HELP BRING FOG NORTHWARDS TOWARDS
THE AIRPORT. IF FOG DOES NOT DEVELOP IN THE SOUTHERN PORTIONS OF THE
VALLEY, DRAINAGE WINDS COULD KEEP THE ATMOSPHERE TOO WELL MIXED TO
ALLOW FOR FOG FORMATION AT SNS.
MARINE
(TONIGHT THROUGH NEXT MONDAY)
ISSUED AT 948 PM PST TUE NOV 25 2025
HIGH PRESSURE OVER OFF THE CALIFORNIA COAST WILL MAINTAIN GENTLE
TO MODERATE NORTHERLY CONDITIONS THROUGH MID WEEK. PATCHY DENSE
FOG WILL BE POSSIBLE AGAIN TONIGHT, ESPECIALLY IN THE BAYS. SEAS
WILL CONTINUE TO SUBSIDE THROUGH WEDNESDAY. WINDS WILL BEGIN TO
INCREASE AGAIN LATE WEEK, BUILDING MODERATE TO ROUGH SEAS.
MTR WATCHES/WARNINGS/ADVISORIES
CA...DENSE FOG ADVISORY UNTIL 11 AM PST WEDNESDAY FOR CAZ510.
PZ...NONE.
SHORT TERM...RGASS
LONG TERM....RGASS
AVIATION...KENNEDY
MARINE...BFG
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