064
FXUS66 KMTR 240903
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
203 AM PDT FRI OCT 24 2025
..NEW SHORT TERM, LONG TERM
KEY MESSAGES
UPDATED AT 1229 AM PDT FRI OCT 24 2025
- PATCHY MORNING FOG WITH SEASONAL WEATHER THIS AFTERNOON
- BENEFICIAL RAIN ACROSS THE BAY AREA ARRIVES SATURDAY
- LARGE SWELL HAS RETURNED WITH HAZARDOUS BEACH CONDITIONS
THROUGH THE WEEKEND
SHORT TERM
ISSUED AT 1229 AM PDT FRI OCT 24 2025
(TODAY AND TONIGHT)
STRATUS IS FILLING IN A SHALLOW MARINE LAYER. AS THE SURFACE
TEMPERATURE CONTINUES TO DROP THROUGH THE EARLY MORNING THERE IS A
30-50% CHANCE FOR FOG TO DEVELOP ALONG THE COAST AND IN THE
VALLEYS. THE HIGH CLOUDS ASSOCIATED WITH SATURDAY'S COLD FRONT ARE
STILL TOO FAR AWAY TO LIMIT RADIATIONAL COOLING TONIGHT. FAVORABLE
CONDITIONS INCLUDE DEW POINTS HIGHER THAN SST, A 13-HOUR LONG
NIGHT, LIGHT WINDS, AND HIGH PRESSURE ALOFT. THIS COMBINATION
SHOULD SUPPORT A COMBINATION OF ADVECTION AND RADIATION FOG. IT'S
NOT A SLAM DUNK, HOWEVER. THE AIR TEMPERATURE IS ALREADY COOLER
THAN THE SST, WHICH CUTS OFF THE MAIN COOLING MECHANISM THAT
CAUSES SATURATION OVER WATER. THE BEST CHANCE IS IN THE COUPLE
HOURS BEFORE OR AFTER SUNRISE, WHICH WOULD OBVIOUSLY IMPACT THE
MORNING COMMUTE. ANY FOG THAT FORMS SHOULD CLEAR BY 10 AM.
OTHERWISE TODAY WILL BE SIMILAR TO YESTERDAY, ALBEIT WITH MORE
HIGH CLOUD COVER SIGNALING THE APPROACHING COLD FRONT. THESE
CLOUDS WILL LIMIT DAYTIME HEATING BY A COUPLE DEGREES, BUT SHOULD
LEAD TO A KILLER SUNSET IF YOU CAN AVOID THE RETURNING MARINE
LAYER STRATUS THIS EVENING.
LONG TERM
ISSUED AT 1229 AM PDT FRI OCT 24 2025
(SATURDAY THROUGH THURSDAY)
PREFRONTAL RAIN WILL BEGIN EARLY SATURDAY MORNING IN THE NORTH
BAY. THE MAIN BAND OF RAIN SHOULD REACH SANTA ROSA AROUND 3 AM,
SAN FRANCISCO BY 5 AM, AND SAN JOSE BY 7 AM. HIGH RESOLUTION
MODELS ARE SHOWING MUCH LESS RAIN THAN PREVIOUSLY EXPECTED, AND
OUR OFFICIAL FORECAST CONTINUES TO TREND IN THAT DIRECTION. THE
06Z HRRR JUMPS OUT WITH LESS THAN 1/10" ACROSS THE BAY AREA AND
HARDLY ANYTHING ACROSS THE INLAND EAST BAY AND SOUTH BAY. THERE
LOOKS TO BE A DISTINCT BREAK SATURDAY NIGHT BEFORE RAIN RETURNS
SUNDAY, THOUGH ONLY ABOUT HALF AS MUCH AS SATURDAY. THE LIGHTNING
THREAT IS MINUSCULE DUE MAINLY TO SHALLOW LAPSE RATES. THE
MOISTURE, SHEAR, AND TRIGGER (COLD FRONT) ARE ALL THERE HOWEVER,
SO IT'S STILL WORTH KEEPING AN EYE ON CONVECTION FOR ANY LOW-
TOPPED ROTATING CELLS. COLDER AIR WILL ACCOMPANY THE FRONT, WITH
THE 850 TEMPERATURE DROPPING TO 7 OR 8C, WHICH IS SOMEWHERE
BETWEEN THE 10TH AND 25TH PERCENTILE FOR THIS TIME OF YEAR.
NOTHING CRAZY, BUT SUNDAY AND MONDAY MORNING WILL FEEL CHILLY AS A
RESULT. THE SURFACE WIND SPEED DOESN'T LOOK VERY HIGH WITH THIS
SYSTEM, BUT THE DIRECTION WILL GRADUALLY SHIFT TO SW AS THE FRONT
APPROACHES. WINDS WILL FLIP BACK TO NW AS THE FRONT MOVES
THROUGH.
AFTER THE POST FRONTAL SHOWERS CLEAR UP MONDAY MORNING, PERIODS OF
ZONAL FLOW AND WEAK RIDGING WILL BRING DRIER AND MORE SEASONAL
CONDITIONS FOR THE MAJORITY OF NEXT WEEK. HALLOWEEN STILL LOOKS
GOOD ON FRIDAY. THERE'S SOME INDICATION THAT THE NEXT SYSTEM COULD
ARRIVE NEXT WEEKEND, BUT ROUGHLY 70% OF ENSEMBLE MEMBERS KEEP A
RIDGING PATTERN.
AVIATION
(06Z TAFS)
ISSUED AT 852 PM PDT THU OCT 23 2025
CURRENTLY A MIXED BAG OF IFR-VFR AT THE TERMINALS. MODERATE TO HIGH
CONFIDENCE IN ALL TERMINALS DEVELOPING AN MVFR CEILING TONIGHT, WITH
IFR-LIFR (FOG) POSSIBLE FOR APC, MRY, SNS, AND STS. HIGH CLOUDS WILL
STREAM IN THROUGH THE TAF PERIOD FROM THE SYSTEM THAT WILL BRING
RAIN CHANCES BY THE NEXT TAF PERIOD FOR THE NORTH BAY.
VICINITY OF SFO...CURRENTLY VFR WITH WESTERLY FLOW. MODERATE
CONFIDENCE (65%) IN A CEILING ON THE CUSP OF MVFR/IFR DEVELOPING
TONIGHT WITH A LATE-MORNING CLEARING TIME. WESTERLY WINDS WILL
PREVAIL THROUGH THE TAF PERIOD. MVFR CEILING RETURNS TOWARDS THE END
OF THE TAF PERIOD.
SFO BRIDGE APPROACH...SIMILAR TO SFO.
MONTEREY BAY TERMINALS...CURRENTLY IFR WITH WESTERLY FLOW AT BOTH
TERMINALS. MODERATE CONFIDENCE (60%) IN FOG DEVELOPING AT BOTH
TERMINALS TONIGHT. VFR IS EXPECTED BY THE AFTERNOON WITH MVFR
CEILINGS WILL DEVELOPING/APPROACHING TOWARDS THE END OF THE TAF
PERIOD.
MARINE
(TONIGHT THROUGH NEXT WEDNESDAY)
ISSUED AT 852 PM PDT THU OCT 23 2025
A MODERATE TO FRESH BREEZE WILL PREVAIL THROUGH MONDAY WITH
ISOLATED STRONG GUSTS. ROUGH SEAS WILL PREVAIL FOR THE INNER
WATERS AND OUTER WATERS, BUILDING TO BECOME VERY ROUGH IN THE
OUTER WATERS OVER THE WEEKEND. LIGHT RAIN SHOWERS RETURN THIS
WEEKEND.
BEACHES
ISSUED AT 1254 PM PDT THU OCT 23 2025
A MODERATE TO LONG PERIOD NORTHWESTERLY SWELL WILL RESULT IN
BREAKING WAVES OF 15 TO 20 FEET, WITH THE HIGHEST WAVES UP TO 25
FEET IN FAVORED LOCATIONS, AND AN INCREASED RISK FOR SNEAKER WAVES
AND RIP CURRENTS LATE TONIGHT THROUGH LATE SUNDAY NIGHT. 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!
MTR WATCHES/WARNINGS/ADVISORIES
CA...BEACH HAZARDS STATEMENT THROUGH LATE SUNDAY NIGHT FOR CAZ006-505-
509-529-530.
PZ...SMALL CRAFT ADVISORY FROM 9 PM THIS EVENING TO 9 AM PDT SATURDAY
FOR PT ARENA TO PT REYES 0-10 NM.
SMALL CRAFT ADVISORY UNTIL 3 AM PDT EARLY THIS MORNING FOR PT
PINOS TO PT PIEDRAS BLANCAS 0-10 NM.
SMALL CRAFT ADVISORY FROM 9 AM THIS MORNING TO 9 PM PDT THIS
EVENING FOR PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM.
SMALL CRAFT ADVISORY UNTIL 9 AM PDT SATURDAY FOR PIGEON PT TO PT
PINOS 10-60 NM-PT ARENA TO PT REYES 10-60 NM.
SHORT TERM...FLYNN
LONG TERM....FLYNN
AVIATION...SARMENT
MARINE...SARMENT
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