406
FXUS66 KMTR 311931
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
1231 PM PDT FRI OCT 31 2025
..NEW SHORT TERM, LONG TERM
KEY MESSAGES
UPDATED AT 1229 PM PDT FRI OCT 31 2025
- NICE AND QUIET WITH WARM TEMPERATURES THROUGH THIS WEEKEND.
- COOLER TEMPERATURES (NEAR AVERAGE) BY THE START OF NEXT WEEK.
- CONFIDENCE INCREASING ON THE NEXT RAIN MAKER, SET TO ARRIVE BY
THE MIDDLE OF THE UPCOMING WEEK.
SHORT TERM
ISSUED AT 1229 PM PDT FRI OCT 31 2025
(THIS EVENING THROUGH SATURDAY)
AS LOW CLOUDS BEGIN TO GIVE WAY TO CLEAR SKIES THIS AFTERNOON,
TEMPERATURES ARE FORECAST TO WARM INTO THE 70S ACROSS INLAND AREAS
(AND THE SANTA CRUZ REGION) WITH 60S NEAR THE COAST. HOWEVER, WHERE
LOW CLOUDS LINGER, TEMPERATURES WILL NOT WARM AS MUCH AS PREVIOUSLY
FORECAST. LOW CLOUDS HAVE THE POTENTIAL TO RETURN TONIGHT, MORE
TYPICAL OF A SUMMER-TIME PATTERN AS A WELL DEFINED AS THE MARINE
LAYER IS FORECAST TO COMPRESS SLIGHTLY, RESULTING IN LESS INLAND
INTRUSION.
TEMPERATURES TONIGHT WILL COOL DOWN TO THE UPPER 40S ACROSS THE
NORTH BAY AND INTERIOR PORTIONS OF THE CENTRAL COAST WITH LOW TO MID
50S ELSEWHERE. ANY LOW CLOUDS AND/OR FOG THAT DO DEVELOP WILL MIX
OUT BY LATE SATURDAY MORNING. AS SUCH, TEMPERATURES SATURDAY
AFTERNOON ARE FORECAST TO BE A BIT WARMER. EXPECTING TEMPERATURES TO
APPROACH 80 DEGREES F IN THE NORTH BAY, EAST BAY, SOUTH BAY AND
INTERIOR AREAS OF THE CENTRAL COAST. THIS WILL BE THE RESULT OF A
SHORT-WAVE RIDGE BUILDING ACROSS SOUTHERN CALIFORNIA AHEAD OF AN
APPROACHING TROUGH WELL TO THE NORTH.
LONG TERM
ISSUED AT 1229 PM PDT FRI OCT 31 2025
(SATURDAY NIGHT THROUGH NEXT THURSDAY)
FOR SUNDAY, EXPECTING THE SAME WEATHER PATTERN AS SATURDAY. NO CLEAR
SINGLE ONE WAY OR ANOTHER FOR THE MONDAY-WEDNESDAY WITH RESPECT TO
RAINFALL. THUS, THOUGHT THE PREVIOUS FORECASTER SUMMED UP THE REST
OF THE LONG TERM DISCUSSION RATHER WELL: "BEYOND THE WEEKEND IS WHEN
WE START TO FIND THE NEXT THING WORTH TALKING ABOUT. MEDIUM-RANGE
GUIDANCE HAS BEEN ADVERTISING A NOTABLE PATTERN CHANGE WITH A DEEP
UPPER LOW IN THE GULF OF ALASKA HELPING TO ERODE THE DOWNSTREAM
RIDGE. THIS OPENS THE DOOR FOR A ROBUST 150 KT PACIFIC JET ACROSS
THE ALEUTIANS TO PROMOTE ANOTHER DEEP UPPER LOW DIGGING INTO THE
EPAC OFF THE WEST COAST. THIS WILL BE OUR STORM TO WATCH. CONFIDENCE
IS INCREASING FOR IMPACTFUL RAINFALL IN THE NORTH BAY ON WEDNESDAY.
ENSEMBLE CLUSTER ANALYSIS SHOWS THAT APPROX 74% OF MEMBERS ADVERTISE
RAINFALL AMOUNTS GREATER THAN THE ENSEMBLE MEAN. ESSENTIALLY WHAT
THIS MEANS IS THAT THERE IS BETTER AGREEMENT ON THE HIGHER END OF
THE MODEL SPREAD. WHAT IS THIS SPREAD? GREAT QUESTION. THE 25TH-75TH
PERCENTILES FOR THE NORTH BAY ARE RUNNING ABOUT 0.75"-1.75" ON
AVERAGE (24 HOUR TOTALS, AND GIVE OR TAKE A HALF INCH DEPENDING ON
WHERE YOU ARE IN THE COUNTY). SURE, NOT OUTSTANDING FOR THE NORTH
BAY, BUT AT LEAST THIS TELLS US THAT WE MAY BE IN FOR A DECENT
RAINFALL. POTENTIALLY THE MOST WE'VE SEEN THIS SEASON IN THOSE
PARTS. THINGS ARE MORE UNCERTAIN FOR THE REST OF THE BAY AREA AND
CENTRAL COAST. THERE IS NOT ENOUGH CERTAINTY HERE TO GIVE A
MEANINGFUL FORECAST AT THIS POINT, BUT AT THE VERY LEAST EXPECT SOME
RAIN AND WIND. MORE ON THE WIND...AS THE TROUGH SWINGS THROUGH ON
WEDNESDAY, WE'LL LIKELY SEE WIDESPREAD IMPACTFUL WINDS ASSOCIATED
WITH THE PASSAGE OF THE UPPER LEVEL JET CORE. CURRENT MODEL GUIDANCE
HINTS AT A DECENT CHANCE OF SEEING 50 KTS AT 850 MB, WHICH WOULD BE
NEAR THE DAILY RECORD MAX FOR THIS TIME OF YEAR. AGAIN, NOTHING
COMPARED TO STRONGER STORMS THAT WE MAY SEE IN DECEMBER-FEBRUARY,
BUT FAIRLY RESPECTABLE FOR THIS POINT IN THE SEASON."
AVIATION
(18Z TAFS)
ISSUED AT 1048 AM PDT FRI OCT 31 2025
SIMILAR TO THURSDAY MORNING, SATELLITE AND OBSERVATIONS SHOW AREAS
OF STRATUS AND FOG /MVFR-IFR-LIFR/ OTHERWISE EXPECT VFR WITH MIXING
OCCURRING THROUGH LATE MORNING AND AFTERNOON. STRATUS AND FOG /IFR-
LIFR/ RETURN TONIGHT INTO SATURDAY MORNING.
VICINITY OF SFO...IFR UNTIL 19Z THEN VFR THROUGH THE AFTERNOON AND
EVENING. WEST TO NORTHWEST WIND NEAR 10 KNOTS INCREASING TO 15 TO 20
KNOTS THIS AFTERNOON AND EARLY EVENING. WEST WIND 7 TO 12 KNOTS FROM
MID EVENING TO SATURDAY.
SFO BRIDGE APPROACH...SIMILAR TO SFO.
MONTEREY BAY TERMINALS...IFR MIXING OUT THROUGH LATE MORNING THEN
VFR DURING THE AFTERNOON. STRATUS AND FOG/MIST /IFR-LIFR/ RETURN
TONIGHT AND SATURDAY MORNING. ONSHORE WINDS 5 TO 10 KNOTS DURING
THE AFTERNOON AND EARLY EVENING BECOMING LIGHT EAST TO SOUTHEAST
TONIGHT AND SATURDAY MORNING.
MARINE
(TODAY THROUGH WEDNESDAY)
ISSUED AT 913 AM PDT FRI OCT 31 2025
FRESH TO STRONG NORTHERLY BREEZES WILL PREVAIL THROUGH THE
WEEKEND, DIMINISHING TO BECOME MODERATE TO FRESH EARLY NEXT WEEK.
MODERATE TO ROUGH SEAS WILL PREVAIL WITH VERY ROUGH SEAS EXPECTED
IN THE OUTER WATERS THIS WEEKEND. UNSETTLED WEATHER WITH RAIN AND
WIND RETURNS LATE TUESDAY NIGHT.
BEACHES
ISSUED AT 410 AM PDT FRI OCT 31 2025
A LONG PERIOD NORTHWESTERLY SWELL WILL BRING AN INCREASED RISK
FOR SNEAKER WAVES AND RIP CURRENTS AND BREAKING WAVES OF 12-17
FEET TO PACIFIC COAST BEACHES SATURDAY THROUGH MONDAY. SNEAKER
WAVES CAN UNEXPECTEDLY RUN SIGNIFICANTLY FARTHER UP THE BEACH THAN
NORMAL, INCLUDING OVER ROCKS AND JETTIES. RIP CURRENTS ARE
TYPICALLY MORE FREQUENT AND STRONGER IN THE VICINITY OF JETTIES,
INLETS, AND PIERS. SWIMMERS SHOULD ALWAYS SWIM NEAR A LIFEGUARD.
REMAIN OUT OF THE WATER TO AVOID HAZARDOUS SWIMMING CONDITIONS AND
NEVER TURN YOUR BACK ON THE OCEAN!
SARMENT
MTR WATCHES/WARNINGS/ADVISORIES
CA...BEACH HAZARDS STATEMENT FROM SATURDAY MORNING THROUGH LATE
MONDAY NIGHT FOR CAZ006-505-509-529-530.
PZ...SMALL CRAFT ADVISORY UNTIL 3 AM PDT SATURDAY FOR PT ARENA TO PT
REYES 0-10 NM-PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM.
SMALL CRAFT ADVISORY UNTIL 3 AM PDT SATURDAY FOR PIGEON PT TO PT
PINOS 0-10 NM.
SMALL CRAFT ADVISORY FROM 9 AM TO 9 PM PDT SATURDAY FOR PIGEON
PT TO PT PINOS 0-10 NM-PT PINOS TO PT PIEDRAS BLANCAS 0-10
NM.
SMALL CRAFT ADVISORY UNTIL 3 AM PDT SUNDAY FOR PIGEON PT TO PT
PINOS 10-60 NM-PT ARENA TO PT REYES 10-60 NM.
SHORT TERM...RGASS
LONG TERM....RGASS/BEHRINGER
AVIATION...CANEPA
MARINE...CANEPA
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