720
FXUS66 KMTR 201759
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
1059 AM PDT SUN SEP 20 2026
..NEW AVIATION
KEY MESSAGES
UPDATED AT 925 PM PDT SAT SEP 19 2026
- BRIEF COOLING SUNDAY THROUGH MONDAY
- MORE SUBSTANTIAL WARMING TREND TUESDAY THROUGH THURSDAY
SHORT TERM
ISSUED AT 925 PM PDT SAT SEP 19 2026
(TONIGHT THROUGH MONDAY NIGHT)
RESIDUAL POLAR JET STREAM WINDS WILL MERGE WITH THE SUBTROPICAL JET
STREAM AT THE BASE OF A WEAK 500 MB LOW CURRENTLY ~ 500 MILES WEST
OF MONTEREY AND MOVE THE LOW EASTWARD ACROSS OUR FORECAST AREA
LATER SUNDAY THROUGH MONDAY. COOL ONSHORE BREEZES WILL HELP KEEP
TEMPERATURES BELOW NORMAL. DAYTIME HIGHS SUNDAY WILL BE COOLER
THAN TYPICAL FOR SEP 20TH WITH HIGHS IN THE 60S COASTSIDE/BAYSIDE
TO THE 70S AND 80S INLAND. HIGHS MONDAY WILL BE ABOUT THE SAME AS
ON SUNDAY. A FEW PATCHES OF LATE NIGHT AND MORNING LIGHT DRIZZLE
MAY FORM IN THE COOLED AIR NEAR SURFACE TO ALOFT.
LONG TERM
ISSUED AT 925 PM PDT SAT SEP 19 2026
(TUESDAY THROUGH NEXT SATURDAY)
500 MB LOW AMPLITUDE RIDGING WILL DEVELOP TUESDAY INTO EARLY
THURSDAY. THIS WILL BRING A WARMING TREND HERE DURING THESE THREE
DAYS, WHICH WILL HELP PUSH DAYTIME HIGHS UP TO THE 90S/100 INLAND
WED-THU (COOLER AT THE COASTLINE AND BAYS). THE PATTERN ACROSS
THE NORTH PACIFIC TO THE WESTERN CONUS IS PROGRESSIVE, WHICH LOWERS
CONFIDENCE A LITTLE IN THE TIMING OF 500 MB RIDGING RESIDENCE TIME
AND THIS MAY INFLUENCE THE DURATION OF WARM/HOT WEATHER CURRENTLY
FORECAST FOR MID NEXT WEEK. STAY TUNED TO THE LATEST UPDATES.
AVIATION
(18Z TAFS)
ISSUED AT 1100 AM PDT SUN SEP 20 2026
HIGH CLOUDS ARE SLOWING THE BURN OFF OF LOW CIGS SO FAR THIS
MORNING BUT CLEARING OF LOW CLOUDS STILL FORECAST AT MOST
TERMINALS AWAY FROM THE COAST BY 19Z. AS LOW CLOUDS BURN BACK IT
WILL BE REPLACED BY EXTENSIVE HIGH CLOUDS PASSING OVER THE REGION
IN ASSOCIATION WITH UPPER LOW OFFSHORE. THIS LOW WILL KEEP THE
MARINE LAYER DEEP WITH LOW CIGS SPREADING INLAND EARLY THIS
EVENING AND LASTING AT LEAST THROUGH 18-19Z MONDAY.
VICINITY OF SFO...LOW CIGS FORECAST TO MIX OUT AROUND 19Z WITH
EXTENSIVE HIGH CLOUDS AND WEST WINDS AROUND 15 KT THIS
AFTERNOON/EVENING. LOW CIGS SPREAD BACK INLAND AROUND 04Z LASTING
OVERNIGHT THROUGH 19Z MONDAY.
SFO BRIDGE APPROACH...LINGERING HAZE AND CIGS AT LEAST THROUGH
19-20Z THIS MORNING BEFORE IMPROVING CONDITIONS LATER THIS
AFTERNOON AND EARLY EVENING.
MONTEREY BAY TERMINALS...LOW CIGS MAY NOT CLEAR FOR KMRY TODAY OR
ONLY INTERMITTENTLY FROM 20-23Z THIS AFTERNOON. KSNS TO CLEAR BY
19Z BUT MID AND HIGH CLOUDS LINGER THROUGH THE DAY. LOW CIGS TO
SPREAD BACK INLAND EARLY THIS EVENING AND LINGER THROUGH 18-19Z
MONDAY.
MARINE
(TODAY THROUGH FRIDAY)
ISSUED AT 416 AM PDT SUN SEP 20 2026
FRESH TO STRONG NORTHERLY BREEZES WILL CREATE HAZARDOUS CONDITIONS
FOR SMALL CRAFT ACROSS MOST OF THE COASTAL WATERS THROUGH MONDAY
MORNING. MODERATE TO FRESH NORTHERLY BREEZES WILL PREVAIL TUESDAY
THROUGH THURSDAY WITH LOCALLY STRONG BREEZES ACROSS THE NORTHERN
OUTER WATERS. SLIGHT TO MODERATE SEAS WILL PREVAIL THROUGH MONDAY,
BUILDING TO BECOME MODERATE TO ROUGH TUESDAY THROUGH THURSDAY.
FIRE WEATHER
ISSUED AT 416 AM PDT SUN SEP 20 2026
NEAR TO SLIGHTLY BELOW NORMAL TEMPERATURES, DIURNAL WINDS, A DEEP
MARINE LAYER, AND A CHANCE FOR DRIZZLE ARE ON TAP FOR SUNDAY AND
MONDAY. WARMING AND DRYING TREND KICKS OFF TUESDAY WITH TEMPERATURES
UP TO 15 DEGREES ABOVE NORMAL BY THURSDAY. AREAS OF MODERATE
HEATRISK ARE EXPECTED AS A RESULT WEDNESDAY AND THURSDAY. THE MARINE
LAYER WILL COMPRESS BELOW 1,000 FEET DURING THIS WARM-UP WITH
NOCTURNAL DRYING EXPECTED ABOVE IT. DIURNAL WINDS WILL PREVAIL;
HOWEVER, THEY WILL BE WEAKER THAN THE PRECEDING DAYS.
MTR WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO 9 PM PDT THIS
EVENING FOR PIGEON PT TO PT PINOS 0-10 NM.
SMALL CRAFT ADVISORY UNTIL 3 AM PDT MONDAY FOR PIGEON PT TO PT
PINOS 10-60 NM-PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM.
SMALL CRAFT ADVISORY UNTIL 9 AM PDT MONDAY FOR PT ARENA TO PT
REYES 10-60 NM.
SHORT TERM...CANEPA
LONG TERM....CANEPA
AVIATION...RW
MARINE...RW
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