893
FXUS66 KMTR 241153
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
453 AM PDT FRI OCT 24 2025
..NEW AVIATION, MARINE
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
(12Z TAFS)
ISSUED AT 451 AM PDT FRI OCT 24 2025
WIDESPREAD CIGS AND LIGHT WINDS ARE AFFECTING THE REGION. EXPECT
MVFR/IFR CIGS FOR MOST AREAS, WHILE THE MONTEREY BAY AND NORTH BAY
TERMINALS LOOK TO FALL TO LIFR WITH POCKETS OF FOG. CIGS AND FOG
ERODE IN THE LATE MORNING AND INTO THE AFTERNOON AS MORE MODERATE TO
BREEZY WINDS BUILD. MVFR CIGS WILL BE QUICK TO RETURN THIS EVENING
ALONG THE COAST AFFECTING HAF AND THEN THE TERMINALS AROUND THE BAYS
AND IN THE NORTH BAY INTO THAT NIGHT. A COLD FRONT MOVES INTO THE
NORTH BAY IN THE LATE NIGHT, SCATTERING LOWER CIGS, BUT KEEPING MID-
LEVEL CLOUDS AND OFFERING LIGHT SHOWERS. THIS FRONT LOOKS TO PASS
INTO THE SF BAY INTO SATURDAY MORNING, BUT SHOWERS LOOK TO BECOME
SPOTTIER AS THE FRONT APPROACHES THE BAY. WINDS WILL STAY MOSTLY
LIGHT INTO THE NIGHT, BUT WILL BECOME SOUTHERLY AND MODERATE AGAIN
AND DURING THE FRONTAL PASSAGE.
VICINITY OF SFO...MVFR CIGS LAST INTO THE LATE MORNING BEFORE
ERODING, EXPECT LIGHT TO MODERATE WINDS THROUGH THE TAF PERIOD WITH
WEST WINDS THROUGH THE LATE NIGHT. MVFR CIGS RETURN INTO THE NIGHT
ALONG WITH BUILDING MID-LEVEL CLOUDS. AS THE FRONT ARRIVES ON
SATURDAY MORNING, WINDS TURN SOUTHWEST, LOWER CIGS SCATTER, AND
SPOTTY SHOWERS MOVE THROUGH THE SF BAY.
SFO BRIDGE APPROACH...SIMILAR TO SFO.
MONTEREY BAY TERMINALS...LIFR CIGS, POCKETS OF FOG, AND LIGHT WINDS
LINGER THROUGH MUCH OF THE MORNING. EXPECT CLEARING CONDITIONS INTO
THE AFTERNOON ALONG WITH MODERATE WINDS BUILDING INTO THE AREA. MVFR
CIGS RETURN TO MRY INTO THE EVENING WITH SNS SEEING CIGS RETURN INTO
THE EARLY NIGHT AS WINDS WEAKEN AT BOTH TAF SITES.
MARINE
(TODAY THROUGH WEDNESDAY)
ISSUED AT 451 AM PDT FRI OCT 24 2025
LIGHT TO MODERATE WINDS LAST INTO THE WEEKEND WITH SOME BREEZY
CONDITIONS EXPECTED ALONG THE FAVORED COASTAL JETS. ROUGH SEAS
WILL PREVAIL FOR THE OUTER WATERS, BUILDING TO BECOME VERY ROUGH
IN THE OUTER WATERS OVER THE WEEKEND. LIGHT RAIN SHOWERS RETURN
THIS WEEKEND. SEAS EASE INTO THE NEXT WORK WEEK, BUT WINDS
INCREASE IN THE SOUTHERN WATERS.
BEACHES
ISSUED AT 451 AM PDT FRI OCT 24 2025
A MODERATE TO LONG PERIOD NORTHWESTERLY SWELL IS BUILDING ACROSS
THE COAST, CAUSING BREAKING WAVES OF 15 TO 20 FEET, WITH THE
HIGHEST WAVES UP TO 25 FEET IN FAVORED LOCATIONS. THIS WILL CAUSE
AN INCREASED RISK FOR SNEAKER WAVES AND RIP CURRENTS 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.
DENSE FOG ADVISORY UNTIL 10 AM PDT THIS MORNING FOR CAZ506.
PZ...SMALL CRAFT ADVISORY FROM 3 AM TO 9 PM PDT SATURDAY FOR SF BAY N
OF BAY BRIDGE.
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 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 PM PDT SATURDAY FOR PT ARENA TO PT
REYES 10-60 NM.
SMALL CRAFT ADVISORY UNTIL 9 AM PDT SATURDAY FOR PIGEON PT TO PT
PINOS 10-60 NM.
SHORT TERM...FLYNN
LONG TERM....FLYNN
AVIATION...MURDOCK
MARINE...MURDOCK
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