960
FXUS66 KMTR 021900
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
1200 PM PDT WED SEP 2 2026
..NEW SHORT TERM, LONG TERM
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
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
(18Z TAFS)
ISSUED AT 1102 AM PDT WED SEP 2 2026
PRIMARILY VFR CONDITIONS WITH MVFR CEILINGS OVER THE NORTH BAY
THAT ARE EXPECTED TO LIFT BY 20Z. A PREFRONTAL BAND OF LIGHT RAIN
WILL CONTINUE TO MOVE ACROSS THE BAY AREA INTO THE EARLY AFTERNOON
WITH LESS THAN 0.10" OF RAINFALL EXPECTED AND MINIMAL IMPACTS. A
VERY DEEP MARINE LAYER (~5000FT) WILL BE COMPRESSED SOMEWHAT
LATER TODAY INTO LATE TONIGHT, THEN DEEPEN AGAIN BY EARLY THURSDAY
MORNING AS A WEAK COLD FRONT MOVES ACROSS OUR AREA AND THE
TROUGHING PATTERN PERSISTS.
VICINITY OF SFO...LIGHT RAIN IN VICINITY OF THE BAY AREA TERMINALS
SHOULD MOVE EAST BY 20Z. VFR IS EXPECTED TO PREVAIL THROUGH THE
REMAINDER OF TODAY AND TONIGHT WITH A CHANCE OF MVFR CEILINGS
DEVELOPING AFTER SUNRISE THURSDAY.
SFO BRIDGE APPROACH...SIMILAR TO SFO.
MONTEREY BAY TERMINALS...VFR THROUGH THE REMAINDER OF TODAY UNTIL
LATER TONIGHT AROUND MIDNIGHT, WHEN MVFR/IFR CEILINGS ARE EXPECTED
TO DEVELOP. AND PERSIST THROUGH THE REMAINDER OF THE FORECAST
PERIOD. CONFIDENCE IS HIGHER THIS FAR SOUTH AWAY FROM THE MORE
PROMINENT INFLUENCE OF THE APPROACHING COLD FRONT TO THE NORTH.
MARINE
(TODAY THROUGH MONDAY)
ISSUED AT 1102 AM PDT WED SEP 2 2026
THE LIGHT NORTHWESTERLY BREEZES WILL CONTINUE THROUGH THE WEEK
WITH OCCASIONAL MODERATE GUSTS AND SLIGHT TO MODERATE WIND DRIVEN
SEAS. DIURNAL WINDS GRADUALLY INCREASE FRIDAY AFTERNOON, AND ONCE
AGAIN SATURDAY ESPECIALLY IN VICINITY OF MONTEREY BAY. TROPICAL
CYCLONE ACTIVITY WILL PRODUCE LONG PERIOD SOUTHERLY SWELL FOR
FRIDAY THROUGH THE WEEKEND.
MTR WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...NONE.
SHORT TERM...SARMENT
LONG TERM....SARMENT
AVIATION...JM
MARINE...JM
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