939
FXUS66 KMTR 290455
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
955 PM PDT FRI AUG 28 2026
..NEW SHORT TERM, LONG TERM
KEY MESSAGES
UPDATED AT 909 PM PDT FRI AUG 28 2026
- CLEAR SKIES AND COOL TEMPERATURES TODAY
- COOLER WEATHER CONTINUES INTO NEXT WEEK
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
(06Z TAFS)
ISSUED AT 841 PM PDT FRI AUG 28 2026
IT'S VFR EXCEPT FOR AREAS OF STRATUS /MVFR-IFR/ ALONG THE
IMMEDIATE COASTLINE. THE MID-LATITUDE WIND FLOW PATTERN IS
RETURNING WITH DRYING AIR TONIGHT AND SATURDAY. THE GFS SHOWS
PRECIPITABLE WATER QUICKLY LOWERING TONIGHT AND SATURDAY, NEAR THE
10TH PERCENTILE ON OAKLAND UPPER AIR SOUNDINGS FOR LATE AUGUST. WITH
DECREASING WATER VAPOR ALOFT THIS WILL RESULT IN RADIATIVE COOLING
AND WITH LINGERING BOUNDARY LAYER MOISTURE IT'S LIKELY TO CONTINUE
COOLING TO SATURATION RESULTING IN ADDITIONAL FOG AND STRATUS
/IFR-LIFR/. DIURNAL SURFACE WARMING WILL MIX OUT FOG AND STRATUS
IMPROVING CONDITIONS TO MVFR-VFR BY LATE SATURDAY MORNING AND
AFTERNOON. STRATUS AND FOG /MVFR-IFR/ REDEVELOP SATURDAY NIGHT.
VICINITY OF SFO...VFR UNTIL TEMPO STRATUS /MVFR/ 06Z-08Z TONIGHT,
THEN STRATUS /MVFR/ PREVAILING TONIGHT TO 18Z SATURDAY MORNING.
THEREAFTER VFR IS FORECAST SATURDAY AFTERNOON TO MID EVENING. WEST
WIND NEAR 15 KNOTS TONIGHT DECREASING TO 8 TO 10 KNOTS LATE TONIGHT
AND SATURDAY MORNING. WEST WIND INCREASING TO 15 TO 25 KNOTS
SATURDAY AFTERNOON AND EVENING.
SFO BRIDGE APPROACH...SIMILAR TO SFO.
MONTEREY BAY TERMINALS...VFR THEN STRATUS /IFR-LIFR/ REDEVELOPS
TONIGHT AND SATURDAY MORNING. SURFACE WARMING WILL MIX OUT STRATUS
BY LATE SATURDAY MORNING AND AFTERNOON. STRATUS /IFR/ REDEVELOPS
SATURDAY NIGHT. WEST TO NORTHWEST WINDS 5 TO 15 KNOTS.
MARINE
(TONIGHT THROUGH NEXT THURSDAY)
ISSUED AT 834 PM PDT FRI AUG 28 2026
FRESH NORTHWEST BREEZES WITH OCCASIONAL NEAR GALE FORCE GUSTS
CONTINUE THROUGH THE WEEKEND AS WELL AS A LONG PERIOD SOUTHERLY
SWELL. THE LONG PERIOD SOUTHERLY SWELL PEAKS ON SATURDAY AROUND 17
TO 18 SECONDS AND GRADUALLY DIMINISHES BY SUNDAY NIGHT. WIND
DRIVEN SEAS BRIEFLY BUILD TO ROUGH SATURDAY AFTERNOON INTO SUNDAY
AND GRADUALLY SUBSIDE TO MODERATE THROUGH NEXT WEEK.
MTR WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...SMALL CRAFT ADVISORY FROM 9 AM SATURDAY TO 3 AM PDT SUNDAY FOR
MRY BAY.
SMALL CRAFT ADVISORY UNTIL 9 AM PDT SUNDAY FOR PIGEON PT TO PT
PINOS 10-60 NM-PT ARENA TO PT REYES 0-10 NM-PT ARENA TO PT
REYES 10-60 NM-PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM.
SMALL CRAFT ADVISORY UNTIL 3 AM PDT SUNDAY FOR PIGEON PT TO PT
PINOS 0-10 NM.
SHORT TERM...FLYNN
LONG TERM....FLYNN
AVIATION...CANEPA
MARINE...CANEPA
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