389
FXUS66 KMTR 030457
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
957 PM PDT WED SEP 2 2026
..NEW AVIATION
KEY MESSAGES
UPDATED AT 1159 AM PDT WED SEP 2 2026
- WELL BELOW NORMAL TEMPERATURES WITH BENEFICIAL, LIGHT RAIN
CHANCES THROUGH THURSDAY
- GRADUAL WARMING AND DRYING TREND WITH THE RETURN OF THE
MARINE LAYER FRIDAY INTO THE WEEKEND
UPDATE
ISSUED AT 850 PM PDT WED SEP 2 2026
NO CHANGES TO THE FORECAST THIS EVENING AS WE WATCH THE COLD FRONT
SLOWLY DRIFT SOUTHWARDS. RAIN REMAINS WELL TO OUR NORTH VIA RADAR,
THOUGH HIGH CLOUDS HAVE STARTED MOVE OVERHEAD. IN BETWEEN THE
BREAKS OF THE HIGH CLOUDS, SATELLITE HAS SHOWN SOME STRATUS
DEVELOPING ALONG THE COAST AND IN SOME VALLEYS. WILL NEED TO KEEP
AN EYE ON THAT AND SEE HOW IT PANS OUT FOR THE AVIATION FORECAST.
SHORT TERM
ISSUED AT 1159 AM PDT WED SEP 2 2026
(THIS AFTERNOON THROUGH THURSDAY)
KMUX SHOWS A BAND OF LIGHT PRECIPITATION BISECTING THE BAY AREA AND
MOVING EAST. STILL WAITING ON A BUCKET TIP SOUTH OF THE GOLDEN GATE
BRIDGE; NONETHELESS, IT WON'T AMOUNT TO MUCH AS THE BAND CONTINUES
TO WEAKEN. THIS PRE-FRONTAL RAIN HAS OVERPERFORMED THE OFFICIAL
FORECAST WITH MT. TAM MEASURING 0.57" IN THE LAST 24 HOURS. THE
OVERPERFORMANCE IS LIKELY DUE TO THE STRUGGLES OF GUIDANCE/MODELS IN
THE SHOULDER SEASONS. THE COLD FRONTAL PASSAGE WILL OCCUR TOMORROW
AFTERNOON/EVENING FROM NORTHWEST TO SOUTHEAST, BRINGING RENEWED
CHANCES FOR RAINFALL ALONGSIDE WELL BELOW NORMAL TEMPERATURES AND
CLOUDY CONDITIONS. THIS SECOND ROUND OF RAIN ALSO RUNS THE RISK OF
OVERPERFORMANCE; HOWEVER, THE FORECAST HAS TRENDED WETTER. TOTALS OF
0.10"-0.50" FOR MOST OF THE NORTH BAY AND 0-0.10" SOUTH OF THE
GOLDEN GATE BRIDGE ARE EXPECTED WITH ACCUMULATION SOUTH OF THE
GOLDEN GATE BRIDGE PRIMARILY FAVORING THE SAN FRANCISCO PENINSULA
COAST. LOOKING AT THE 90TH PERCENTILE, TOTALS GET BUMPED UP WITH UP
TO 1.00" POSSIBLE IN THE HIGHER TERRAIN OF THE NORTH BAY AND UP TO
0.50" ALONG THE SAN FRANCISCO PENINSULA COAST. WHILE RAINFALL IS
EXPECTED TO BE BENEFICIAL, WET ROADWAYS WILL CREATE SLICK DRIVING
CONDITIONS AND INCREASE STOPPING DISTANCE. WIND ADVISORY CRITERIA IS
NOT EXPECTED TO BE MET; HOWEVER, GUSTS OF 30-40 MPH CAN BE EXPECTED
THROUGH GAPS/PASSES AND DOWN THE SALINAS VALLEY.
LONG TERM
ISSUED AT 1159 AM PDT WED SEP 2 2026
(FRIDAY THROUGH NEXT TUESDAY)
A CUTOFF LOW WILL SPAWN IN THE PACIFIC NORTHWEST FROM REMNANT UPPER-
LEVEL TROUGHING AS RIDGING EXPANDS WESTWARD INTO THE DESERT
SOUTHWEST. THE LOW IS EXPECTED TO FILL THROUGH THE WEEKEND, GIVING
THE RIDGE INCREASING INFLUENCE OVER THE FORECAST. AS SUCH, A
GRADUAL WARMING AND DRYING TREND AND THE REFORMATION OF THE MARINE
LAYER IS EXPECTED OVER THE WEEKEND. THESE FEATURES WILL ALSO BE
ENOUGH TO SHUNT MOISTURE FROM TROPICAL STORM MARIE SOUTH OF THE
CALIFORNIA BIGHT, AT LEAST FOR NOW. EVEN WITH A CUTOFF LOW IN
PLAY, THERE IS RELATIVELY GOOD AGREEMENT IN THE FORECAST THROUGH
MONDAY. BY TUESDAY, THE ECMWF AND GFS BEGIN TO DRASTICALLY DIVERGE
ON THEIR SOLUTIONS WITH MARIE. THE ONE TO WATCH WILL BE THE ECMWF
AS IT HAS ANOTHER CUTOFF LOW DIGGING, ABSORBING, AND BRINGING
WHAT WAS MARIE INTO CENTRAL CALIFORNIA, WHICH WOULD BE A LOW
PROBABILITY OUTLIER AT THE MOMENT. IT'S IMPERATIVE TO NOTE THAT IF
IT REACHES CALIFORNIA:
MARIE WILL NO LONGER BE TROPICAL AND THE PRIMARY IMPACT WILL BE
RAINFALL.
AVIATION
(06Z TAFS)
ISSUED AT 957 PM PDT WED SEP 2 2026
MINIMAL CHANGES TO THE TAF PACKAGE THIS EVENING. THE NEAR TERM
CHANGES COVERED STRATUS THAT HAS STARTED TO FORM ALONG THE COAST
AND IN SOME OF THE VALLEYS. OUTSIDE OF THAT, WE AWAIT THE ARRIVAL OF
A COLD FRONT. THE HIGHEST CHANCES FOR RAIN WILL BE FOR THE NORTH BAY
TERMINALS WITH CHANCES DECREASING AROUND THE SAN FRANCISCO BAY.
HEAVIER POCKETS OF RAIN MAY BRING REDUCED VISIBILITY AT TIMES, BUT
MOST SITES WILL SEE AT LEAST MVFR TO POTENTIALLY IFR CIGS WITH THE
PASSAGE OF THE FRONT. VFR CIGS MAY RETURN AS EARLY AS THE LATE
MORNING AREAS FOR SOME TERMINALS, FOR NORTH BAY TERMINALS.
CLEARING SKIES WILL GRADUALLY FOLLOW FOR TERMINALS SOUTH OF
THERE, WITH A SLOT FOR CLEAR SKIES. MODELS HINT AT STRATUS TRYING TO
REFORM LATE THURSDAY NIGHT INTO FRIDAY MORNING BUT CONFIDENCE WAS
TOO LOW TO ADD TO MOST TERMINALS.
VICINITY OF SFO...STRATUS FORMED OFF THE WEST SIDE OF THE SAN
FRANCISCO PENINSULA AND AROUND KOAK THIS EVENING; HOWEVER, KSFO
HAS BEEN LUCKY WITH ONLY HIGH CLOUDS BEING REPORTED. CONFIDENCE
REMAINS LOW WITH THE STRATUS FORECAST HERE, SO OPTED TO REMAIN
OPTIMISTIC DURING THE OVERNIGHT HOURS. THOUGH LOWER CLOUDS ARE
EXPECTED WITH THE PASSAGE OF THE FRONT. WE'LL BE WATCHING THE
FRONTAL PASSAGE, WHICH SHOULD REACH THE SAN FRANCISCO AREA THURSDAY
MORNING. THE BEST CHANCES FOR RAIN LOOK TO BE BETWEEN 14-20Z WITH
PERHAPS SOME VICINITY SHOWERS OR MVFR TYPE CIGS LINGERING INTO THE
MID AFTERNOON. WINDS WILL BE FROM THE SOUTH EARLY ON AND GETTING TO
ABOUT 15KT BY THE LATE MORNING OR EARLY AFTERNOON. FLOW BECOMES
WEST/NORTHWEST ONCE THE FRONT PASSES, WITH SUSTAINED 15KT WINDS
THROUGH ROUGHLY SUNSET. CIGS SHOULD GRADUALLY IMPROVE WITH THE
FRONTAL PASSAGE AS WELL.
SFO BRIDGE APPROACH...SIMILAR TO SFO.
MONTEREY BAY TERMINALS...THE HRRR SEEMS TO BE DOING ALRIGHT THIS
MORNING, CAPTURING THE BLIP OF STRATUS HUGGING THE NORTHERN
PORTION OF THE MONTEREY BAY AND SLINKING INTO THE NORTHERN SALINAS
VALLEY. MODELS SHOW STRATUS FLIRTING AROUND KSNS FOR THE NEXT COUPLE
OF HOURS, WITH STRATUS RETURNING AFTER MIDNIGHT BUT CLEARING SHORTLY
AFTER SUNRISE. BROUGHT CIGS UP A BIT TO MVFR LEVELS RATHER THAN
KEEPING THEM AT IFR GIVEN LAST NIGHTS OBSERVATIONS, BUT THE MARINE
LAYER AND STRATUS HAVE HUMBLED US BEFORE. NONETHELESS, IT SHOULD BE
SHORT LIVED AS IT RETREATS TO THE COAST DURING THURSDAY MORNING AND
A FRONT SLOWLY MEANDERS SOUTHWARD. VFR CIGS ARE EXPECTED BY 13-15Z
THU, WITH HIGH CLOUDS RETURNING TO THE FORECAST FOR THE AFTERNOON.
AROUND OR SHORTLY AFTER 0Z FRI, STRATUS LOOKS TO MAKE ARE RETURN TO
KSNS AND KMRY.
MARINE
(TONIGHT THROUGH NEXT TUESDAY)
ISSUED AT 850 PM PDT WED SEP 2 2026
A WEAK COLD FRONT WILL MOVE THROUGH THE REGION LATE TONIGHT AND
INTO THURSDAY MORNING. WINDS WILL CONTINUE TO SHIFT AHEAD OF ITS
ARRIVAL WITH GENTLE TO MODERATE SOUTHWEST BREEZES EXPECTED. RAIN
CHANCES ARE BEST NORTH OF PIGEON POINT DURING THE MORNING AND
EARLY AFTERNOON HOURS, WITH ISOLATED SHOWERS POSSIBLE DOWN TO
POINT PINOS DURING THE AFTERNOON. NORTHWEST WINDS RETURN BEHIND
THE FRONT AND WILL BE GENTLE TO MODERATE. DIURNAL WINDS INCREASE
MORE FRIDAY AND SATURDAY AFTERNOON, ESPECIALLY IN VICINITY OF
MONTEREY BAY. THE TROPICAL ACTIVITY WELL TO OUR SOUTH WILL PRODUCE
LONG PERIOD SOUTHERLY SWELL BEGINNING FRIDAY AND CONTINUING
THROUGH THE WEEKEND INTO THE BEGINNING OF NEXT WEEK.
MTR WATCHES/WARNINGS/ADVISORIES
CA...BEACH HAZARDS STATEMENT FROM FRIDAY MORNING THROUGH MONDAY
EVENING FOR CAZ006-505-509-529-530.
PZ...NONE.
SHORT TERM...SARMENT
LONG TERM....SARMENT
AVIATION...KR
MARINE...KR
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