172
FXUS66 KMTR 172347
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
447 PM PDT SAT OCT 17 2026
..NEW AVIATION
KEY MESSAGES
UPDATED AT 139 PM PDT SAT OCT 17 2026
- VERY WARM TEMPERATURES CONTINUE TODAY
- HAZARDOUS BEACH CONDITIONS THROUGH AT LEAST THIS WEEKEND
- MUCH COOLER WEATHER ARRIVES SUNDAY WITH RAIN CHANCES MIDWEEK
SHORT TERM
ISSUED AT 139 PM PDT SAT OCT 17 2026
(THIS EVENING THROUGH SUNDAY NIGHT)
THIS AFTERNOON IS SHAPING UP TO BE ANOTHER VERY WARM DAY WITH
TEMPERATURES REACHING INTO THE UPPER 80S TO LOW 90S ACROSS THE
INTERIOR, AROUND THE SANTA CRUZ REGION, AND MONTEREY BAY REGION.
TEMPERATURES REACHED THE LOW 90S AROUND MONTEREY REGION AS ONSHORE
FLOW WAS DELAYED. HOWEVER, THE ONSHORE FLOW HAS RETURNED COOLING
TEMPERATURES INTO THE UPPER 70S TO MID 80S. THE IMMEDIATE
COASTLINE IS FORECAST TO REMAIN IN THE LOW-TO-UPPER 70S. THAT
SAID, THE HIGH PRESSURE OVER NORTHERN CALIFORNIA IS WEAKENING AND
WILL CONTINUE TO DO SO THROUGH THE REMAINDER OF THE WEEKEND.
THE COOLING TREND WILL BE MORE ROBUST TONIGHT AND INTO SUNDAY AS
A DRY FRONTAL BOUNDARY MOVES ACROSS THE BAY AREA AND NORTH CENTRAL
COAST. THIS WILL ALSO ALLOW FOR A SLIGHTLY STRONGER ONSHORE FLOW
AND DEEPENING MARINE LAYER (ALBEIT TEMPORARILY) AND MORE
SEASONABLE TEMPERATURES. THUS, TEMPERATURES WILL BE SOME 10-15
DEGREES OR MORE COOLER THAN TODAY.
LONG TERM
ISSUED AT 139 PM PDT SAT OCT 17 2026
(MONDAY THROUGH NEXT FRIDAY)
A MORE ROBUST COOL DOWN WILL OCCUR MONDAY AS THE UPPER-LEVEL
TROUGH DEEPENS OFF OF THE WEST COAST, BRINGING TEMPERATURES TO
BELOW SEASONAL AVERAGES. THE TROUGH BECOMES A CUT-OFF LOW BY
TUESDAY WITH ITS CENTER APPROXIMATELY 350 MILES WEST OF SAN
FRANCISCO. THIS WILL BRING A COLD FRONT THROUGH THE REGION MONDAY
NIGHT INTO TUESDAY MORNING AS THE CENTER OF THE LOW PRESSURE
SYSTEM PUSHES INLAND ACROSS THE SOUTH CENTRAL COAST AND/OR
SOUTHERN CALIFORNIA WEDNESDAY EVENING INTO THURSDAY. THIS WILL
RESULT IN UNSETTLED WEATHER CONDITIONS ACROSS THE REGION TUESDAY
THROUGH THURSDAY.
AS FAR AS PRECIPITATION AND THUNDERSTORM CHANCES GO, THERE IS A
20- 40% CHANCE OF RAIN SHOWERS ACROSS THE GREATER BAY AREA AND
30-60% CHANCE ACROSS THE CENTRAL COAST. THE GREATEST POTENTIAL FOR
CONVECTION IS NOW ON WEDNESDAY WHEN THE CORE OF THE LOW BEGINS TO
MOVE ONSHORE. THE GREATEST POTENTIAL (GENERALLY 15% OR LESS) WILL
BE OVER THE OFFSHORE WATERS AND CENTRAL COAST WHERE THE GREATEST
INSTABILITY WILL BE LOCATED.
A FURTHER OFFSHORE AND SOUTHERN TRACK OF THE LOW PRESSURE SYSTEM
WOULD RESULT IN LESS RAINFALL AND LOWER PROBABILITY FOR
CONVECTION. HOWEVER, IF IT WERE TO MOVE DIRECTLY INTO THE CENTRAL
COAST (OR EVEN THE BAY AREA) WE WOULD HAVE STRONGER WINDS, HEAVIER
RAIN, AND INCREASED POTENTIAL FOR THUNDERSTORMS. THUS, BE SURE TO
CHECK BACK ON THE FORECAST AS THE EVENT DRAWS NEARER.
AVIATION
(00Z TAFS)
ISSUED AT 442 PM PDT SAT OCT 17 2026
LINGERING WEAK OFFSHORE FLOW HAS KEPT DRY AIR IN PLACE WITH VFR
CONDITIONS. EXPECT VFR THROUGH MOST OF TONIGHT. GUIDANCE STILL
GIVES ABOUT A 30% CHC FOR MVFR AT KSTS, BUT GIVEN THE CONF WILL
KEEP THE SCT TO SHOW SOME POSS CLOUDS. IFR TO LIFR MORE LIKELY AT
KHAF,KMRY,KSNS TOMORROW WITH SHALLOW MOISTURE LAYER. OVERALL CONF
REMAINS HIGH.
VICINITY OF SFO...VFR. GUSTY ONSHORE THIS EVENING THEN WEAKENING
OVERNIGHT. ONSHORE PUSH AGAIN TOMORROW AFTERNOON WITH GUSTS OVER
20KTS.
SFO BRIDGE APPROACH...SIMILAR TO SFO.
MONTEREY BAY TERMINALS...VFR THROUGH EARLY TONIGHT. NEED STRATUS
TO DEVELOP OVERNIGHT AND IF IT DOES IT WILL BE SHALLOW LEADING TO
IFR TO LIFR CONDITIONS SUNDAY AM. VFR SUNDAY AFTERNOON.
MARINE
(TODAY THROUGH THURSDAY)
ISSUED AT 1002 AM PDT SAT OCT 17 2026
MODERATE TO FRESH NORTHWESTERLY BREEZES WILL PREVAIL THROUGH
MONDAY WITH STRONG BREEZES ACROSS THE NORTHERN OUTER WATERS.
WIDESPREAD HAZARDOUS CONDITIONS WILL SPREAD ACROSS THE COASTAL
WATERS AS A RESULT SUNDAY AFTERNOON, LIKELY CONTINUING INTO
MONDAY. MODERATE SEAS WILL PREVAIL ACROSS THE INNER WATERS WITH
ROUGH SEAS BUILDING ACROSS THE OUTER WATERS SATURDAY THROUGH
MONDAY, REBUILDING AGAIN TUESDAY. LIGHT RAIN IS EXPECTED MONDAY
NIGHT THROUGH WEDNESDAY.
BEACHES
ISSUED AT 1002 AM PDT SAT OCT 17 2026
HAZARDOUS BEACH CONDITIONS WILL BE PRESENT AT PACIFIC COAST BEACHES
THROUGH SUNDAY AND LIKELY INTO NEXT WEEK. LONG PERIOD
SOUTHERLY/SOUTHWESTERLY SWELL WILL BRING AN INCREASED RISK FOR
SNEAKER WAVES AND STRONG RIP CURRENTS WITH BREAKING WAVES OF 7 TO 12
FEET. REMAIN OFF JETTIES, PIERS, ROCKS, AND OTHER WATERSIDE
INFRASTRUCTURE AS WAVES CAN SWEEP ACROSS THE SHORELINE WITHOUT
WARNING, PULLING PEOPLE INTO THE SEA. NEVER TURN YOUR BACK ON THE
OCEAN!
MTR WATCHES/WARNINGS/ADVISORIES
CA...BEACH HAZARDS STATEMENT THROUGH SUNDAY EVENING FOR CAZ006-505-
509-529-530.
PZ...SMALL CRAFT ADVISORY FROM 3 AM TO 9 PM PDT SUNDAY FOR PT ARENA
TO PT REYES 0-10 NM.
SMALL CRAFT ADVISORY FROM 3 PM TO 9 PM PDT SUNDAY FOR PIGEON PT
TO PT PINOS 0-10 NM-PIGEON PT TO PT PINOS 10-60 NM-PT PINOS
TO PT PIEDRAS BLANCAS 0-10 NM-PT REYES TO PIGEON PT 0-10 NM.
SMALL CRAFT ADVISORY UNTIL 9 PM PDT SUNDAY FOR PT ARENA TO PT
REYES 10-60 NM.
SHORT TERM...RGASS
LONG TERM....RGASS
AVIATION...MM
MARINE...SARMENT
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