666
FXUS66 KMTR 291855
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
1155 AM PDT SAT AUG 29 2026
..NEW AVIATION
KEY MESSAGES
UPDATED AT 909 PM PDT FRI AUG 28 2026
- CLEAR SKIES AND COOL TEMPERATURES TODAY
- COOLER WEATHER CONTINUES INTO NEXT WEEK
UPDATE
ISSUED AT 914 AM PDT SAT AUG 29 2026
EXTENDED THE DENSE FOG ADVISORY THROUGH 10 AM FOR THE NORTH BAY
VALLEYS, HOWEVER SEEING SOME IMPROVEMENT IN VISIBILITIES ACROSS THE
101 HIGHWAY CORRIDOR WITH NAVATO NOW AT 1 MILE WHILE PETALUMA AND
SANTA ROSA/SONOMA COUNTY AIRPORT BOTH AT 1/2 MILE. EXPECTING MOSTLY
SUNNY CONDITIONS REGIONWIDE AS LOW CLOUDS AND FOG DISSIPATE. STILL
EXPECTING SEASONABLY COOL TEMPERATURES TODAY AS THE TROUGH OF LOW
PRESSURE DEEPENS OFF OF THE PACIFIC NORTHWEST COAST. NO UPDATES
PLANNED AS THE ONGOING FORECAST REMAINS ON TRACK THIS MORNING.
RGASS
SHORT TERM
ISSUED AT 909 PM PDT FRI AUG 28 2026
(TONIGHT THROUGH SUNDAY)
WHILE THERE WERE SOME LIGHT SHOWERS FRIDAY, THE LIGHTNING NEVER
HAPPENED AND THAT THREAT IS NOW OVER. THE 00Z SOUNDING MEASURED
1.32" OF PRECIPITABLE WATER. THAT'S WELL OVER THE 90TH PERCENTILE
(1.04"), AND NEAR THE MAXIMUM RECORDED FOR THIS DATE (1.38").
DESPITE THIS NEAR RECORD MOISTURE, DRY AIR IS MOVING IN FROM THE
NORTHWEST REMARKABLY FAST. THE ECMWF ENSEMBLE MEAN PREDICTS THE PW
WILL DROP FROM 1.38" FRIDAY TO AROUND 0.5" SATURDAY. THAT MEANS
THE ATMOSPHERIC MOISTURE IS DECREASING FROM WELL OVER THE 90TH
PERCENTILE ALL THE WAY DOWN TO THE 10TH PERCENTILE IN ONLY 12-24
HOURS.
AS A RESULT OF THE MUCH DRIER AIR, THE SKIES WILL BE MOSTLY CLEAR
SATURDAY. THE MARINE LAYER IS TRYING TO RE-ORGANIZE, BUT ANY
STRATUS WILL LIKELY BE PATCHY AND EVAPORATE IN THE MID TO LATE MORNING.
THE MID AND HIGH LEVEL CLOUDS ARE ALREADY CLEARING AND WILL NOT
RETURN ANYTIME SOON. DESPITE THE SUNSHINE, TEMPERATURES WILL
REMAIN SEVERAL DEGREES COOLER THAN NORMAL THIS WEEKEND.
LONG TERM
ISSUED AT 909 PM PDT FRI AUG 28 2026
(SUNDAY NIGHT THROUGH NEXT FRIDAY)
UPPER LEVEL TROUGHING WILL PERSIST THROUGH THE WEEK, WITH A FEW
EMBEDDED SHORTWAVE FEATURES BRINGING SOME EARLY RAIN TO THE
PACIFIC NORTHWEST. IN THE BAY AREA, RAIN IS LESS LIKELY, BUT THE
COOLING TREND WILL CONTINUE THROUGH AT LEAST THE MIDDLE OF THE
WEEK. MAX TEMPERATURES WILL BE ROUGHLY 10-15 DEGREES BELOW NORMAL
FROM MONDAY THROUGH WEDNESDAY. THE 850 MB TEMPERATURE IS EXPECTED
TO DROP BELOW THE 25TH PERCENTILE (16.1C) BY TUESDAY MORNING.
AVIATION
(18Z TAFS)
ISSUED AT 1151 AM PDT SAT AUG 29 2026
VFR PREVAILS THIS AFTERNOON AS MODERATE ONSHORE WINDS INCREASE WITH
A FEW SITES EXPERIENCING STRONG GUSTS AROUND 20 KT IN THE LATE
AFTERNOON. ONSHORE WINDS BECOME GENTLE THROUGH THE EVENING INTO THE
OVERNIGHT HOURS. THE OAK 12Z SOUNDING FROM THIS MORNING MEASURED THE
MARINE LAYER AT A DEPTH OF ~1400 FT. AN UPPER LEVEL LOW SITUATED
OVER OUR AREA IS EXPECTED TO DEEPEN THE MARINE LAYER FURTHER. A MIX
OF IFR TO LOW-END MVFR CEILINGS RETURN TONIGHT ACROSS THE TERMINALS
WITH MEDIUM CONFIDENCE ON ARRIVAL TIMES AND CEILING HEIGHTS.
VICINITY OF SFO...NORTHWEST TO WESTERLY MODERATE WINDS PREVAIL INTO
THE EVENING WITH FREQUENT STRONG GUSTS AROUND 20 TO 25 KT AT SFO.
OAK MAY EXPERIENCE OCCASIONAL 20 KT GUSTS DURING THE AFTERNOON.
WINDS EASE AFTER SUNSET INTO THE OVERNIGHT HOURS. RELIED ON
PERSISTENCE FROM LAST NIGHT ON STRATUS ARRIVAL WITH MEDIUM
CONFIDENCE FOR MVFR CEILINGS. SOME MODEL GUIDANCE HINTED AT THE
POSSIBILITY FOR IFR CEILINGS SIMILAR TO LAST NIGHT, BUT GIVEN THE
EXPECTED DEEPENING OF THE MARINE LAYER, THE TAF ADVERTISES LOW-END
MVFR.
SFO BRIDGE APPROACH...OCCASIONAL STRONG GUSTS THROUGH THE AFTERNOON.
CLOUD COVER MAY BE PATCHY OVERNIGHT, DEPENDING ON HOW WELL ORGANIZED
THE MARINE LAYER BECOMES. OTHERWISE, SIMILAR TO SFO.
MONTEREY BAY TERMINALS...VFR THROUGH THE AFTERNOON WITH AN EARLY
ARRIVAL OF IFR CEILINGS AROUND SUNSET FOR MRY AND AFTER SUNSET FOR
SNS. MODERATE ONSHORE WINDS PREVAIL THROUGH THE DAY AND DIMINISH TO
GENTLE OVERNIGHT.
MARINE
(TODAY THROUGH THURSDAY)
ISSUED AT 914 AM PDT SAT AUG 29 2026
NORTHWEST WINDS REMAIN FRESH WITH STRONG TO NEAR GALE FORCE GUSTS
TODAY INTO SUNDAY NIGHT. IN RESPONSE, WIND DRIVEN SEAS BUILD TO
ROUGH THIS AFTERNOON AND STEADILY SUBSIDE TO MODERATE THROUGH NEXT
WEEK. A LONG PERIOD SOUTHERLY SWELL ALSO PEAKS TODAY AROUND 17 TO
18 SECONDS AND GRADUALLY DIMINISHES BY SUNDAY NIGHT.
MTR WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 3 AM PDT SUNDAY FOR MRY BAY-PIGEON PT
TO PT PINOS 0-10 NM.
SMALL CRAFT ADVISORY UNTIL 3 AM PDT MONDAY FOR PT ARENA TO PT
REYES 0-10 NM-PT ARENA TO PT REYES 10-60 NM.
SMALL CRAFT ADVISORY UNTIL 9 PM PDT SUNDAY FOR PIGEON PT TO PT
PINOS 10-60 NM-PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM.
SHORT TERM...FLYNN
LONG TERM....FLYNN
AVIATION...NAVARRETE
MARINE...NAVARRETE
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