668
FXUS66 KMTR 231151
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
451 AM PDT SAT MAY 23 2026
..NEW AVIATION
KEY MESSAGES
UPDATED AT 1200 AM PDT SAT MAY 23 2026
- DIURNALLY DRIVEN ONSHORE WINDS DURING THE AFTERNOON AND EARLY
EVENING THROUGH THE EARLY PART OF NEXT WEEK
- GRADUAL COOLING TREND BEGINS TODAY WITH SEASONAL TEMPERATURES
FOR THE UPCOMING WEEKEND AND COOLER TEMPERATURES EARLY NEXT
WEEK
SHORT TERM
ISSUED AT 1200 AM PDT SAT MAY 23 2026
(TODAY AND TONIGHT)
EXTENSIVE STRATUS HAS DEVELOPED ALONG THE COAST AND HAS FLOWED INTO
THE NORTH BAY VALLEYS, THE NORTHERN PART OF THE EAST BAY, THE
MONTEREY BAY REGION, AND THE SALINAS VALLEY. READINGS FROM THE
BODEGA BAY PROFILER REVEAL A MARINE LAYER DEPTH OF AROUND 2000 FEET,
WHICH WOULD ALLOW FOR EXTENSIVE INLAND COVERAGE OF MARINE LAYER
STRATUS THIS MORNING AND WOULD LIMIT THE CLEARING OF STRATUS THROUGH
THE AFTERNOON HOURS. THE UPPER LEVEL PATTERN IS ALSO PROMOTING ZONAL
FLOW ACROSS THE STATE, REINFORCING THE COOLER AND MILDER CONDITIONS.
THUS, TODAY'S HIGHS ARE A LITTLE COOLER THAN YESTERDAY'S AS THE
INLAND VALLEYS REACH THE 70S AND THE LOWER 80S, WHILE AREAS NEAR THE
BAYS SEE HIGHS IN THE MIDDLE 60S TO LOWER 70S AND THE PACIFIC COAST
HOVERS IN THE UPPER 50S. BREEZY ONSHORE WINDS WILL DEVELOP DURING
THE AFTERNOON AND EVENING HOURS WITH GUSTS UP TO 20 MPH THROUGH
FAVORED GAPS AND PASSES.
LONG TERM
ISSUED AT 1200 AM PDT SAT MAY 23 2026
(SUNDAY THROUGH FRIDAY)
A SLIGHT COOLING MAY BE NOTICEABLE IN THE INLAND VALLEYS ON SUNDAY
WITH HIGH TEMPERATURES UP TO 5 DEGREES COOLER, BUT OTHERWISE
CONDITIONS WILL BE SIMILAR TO TODAY WITH EXTENSIVE MORNING STRATUS
AND BREEZY ONSHORE WINDS IN THE AFTERNOON AND EVENING HOURS. THE
COOLING TREND CONTINUES THROUGH THE EARLY PART OF NEXT WEEK WITH A
COLD FRONT ASSOCIATED WITH A DEEP UPPER LEVEL LOW EXPECTED TO SWEEP
THROUGH THE REGION SOMETIME ON TUESDAY, WITH TEMPERATURES IN THE 70S
ACROSS THE INTERIOR VALLEYS, THE MIDDLE TO UPPER 60S NEAR SAN
FRANCISCO BAY AND SANTA CRUZ, AND THE UPPER 50S TO LOWER 60S NEAR
THE PACIFIC COAST AND THE SOUTHERN MONTEREY BAY REGION. BREEZY WINDS
WILL DEVELOP ACROSS THE REGION WITH STRONG GUSTS THROUGH THE FAVORED
GAPS AND PASSES. ALTHOUGH THERE IS A VERY SLIGHT CHANCE (AROUND 10%
PROBABILITY) OF LIGHT SHOWERS OR DRIZZLE POPPING UP IN THE COASTAL
REGIONS, WIDESPREAD WETTING RAINS (RAIN TOTALS AT LEAST A TENTH OF
AN INCH) ARE NOT EXPECTED.
GRADUAL WARMING IS EXPECTED ONCE THE COLD FRONT PASSES ON WEDNESDAY,
WITH LINGERING NORTHERLY WINDS SPARKING SOME EARLY CONCERN FOR
ELEVATED FIRE WEATHER RISKS IN THE INTERIOR, ALTHOUGH IT'S A LITTLE
TOO EARLY TO PIN DOWN EXACT DETAILS AT THIS POINT. I'M NOT ONE
HUNDRED PERCENT SOLD ON WARMING ON THE SCALE THAT THE NBM MODEL
OUTPUT DEPICTS, BUT IT DOES APPEAR THAT TEMPERATURES IN THE 80S ARE
AT LEAST POSSIBLE FOR THE INLAND VALLEYS. BEYOND THE 7-DAY OUTLOOK,
THE FORECAST BECOMES MORE UNCERTAIN AS ENSEMBLE MEMBERS DIFFER ON
HOW QUICKLY THAT UPPER LEVEL LOW FILLS IN AND HOW THE PATTERN
EVOLVES WHEN IT DOES. THE CPC OUTLOOK LEANS TOWARDS TEMPERATURES
WARMER THAN THE SEASONAL AVERAGE (HIGHS AROUND 65 DEGREES FOR
DOWNTOWN SAN FRANCISCO) AND PRECIPITATIONS TOTALS NEAR THE SEASONAL
AVERAGE (RAIN TOTALS AROUND ONE OR TWO HUNDREDTHS OF AN INCH OF RAIN
PER DAY FOR DOWNTOWN SAN FRANCISCO) FOR THE LAST COUPLE DAYS OF MAY
INTO THE FIRST WEEK OF JUNE.
AVIATION
(12Z TAFS)
ISSUED AT 451 AM PDT SAT MAY 23 2026
THE MARINE LAYER LOOKS TO BE AROUND 1500 FEET THIS MORNING, SOCKING
IN THE NORTH BAY, CENTRAL COAST VALLEYS, AND REALLY ONLY ELUDING THE
SOUTH BAY AND INTERIOR EAST BAY TERMINALS. SO FAR OBSERVATIONS HAVE
MOSTLY BEEN HOLDING MVFR CIGS AROUND OVC015, THOUGH REPORTS SHOWED
BRIEF IFR CIGS. CURRENT THINKING IS THAT MOST SITES WILL BE MVFR
THROUGH THE PERIOD, WITH THE POTENTIAL FOR IFR CREEPING UP AROUND
SUNRISE. STRATUS ERODES MID TO LATE MORNING, AND LOOKS TO MAKE A
RETURN LATER THIS EVENING AND INTO THE OVERNIGHT HOURS.
SFO BRIDGE APPROACH... THE DONUT HOLE HAS PARTIALLY FILLED THIS
MORNING, WITH KSFO FINALLY REPORTING BKN MVFR CIGS. THE HREF HAS
KIND OF PICKED UP THE BEST ON THIS, WITH IT POTENTIALLY FILLING ALL
THE WAY IN OVER THE NEXT FEW HOURS. WHETHER OR NOT THAT OCCURS,
MODELS DO AGREE WITH STRATUS CLEARING BY MID TO LATE MORNING WITH
PERHAPS A FEW CLOUDS LINGERING INTO THE AFTERNOON. MAINLY WEST-
SOUTHWEST TO TO SOUTHWEST WINDS ARE EXPECTED, WITH WINDS UP TO 12-
15KT EXPECTED THIS AFTERNOON. THE MARINE LAYER LOOKS TO RETURN
TONIGHT, WHICH SHOULD BRING ANOTHER ROUND OF MVFR CIGS. CONFIDENCE
IS LOW TO MEDIUM FOR THE TIMING OF THE STRATUS LATER TONIGHT.
CONFIDENCE IS MODERATE TO HIGH FOR THIS MORNING'S STRATUS.
SIMILAR TO SFO.
MONTEREY BAY TERMINALS...STRATUS BLANKETS THE BAY THIS MORNING, WITH
KSNS AND KMRY REPORTING MVFR CIGS SO FAR. PRIOR FORECASTS HAD THE
CIGS DROPPING TO IFR BY NOW; HOWEVER, IFR CIGS OVERALL HAVE BEEN
HARD TO FIND. IF WE GET IFR CIGS, PERHAPS IT'LL BRIEFLY BE AROUND
SUNRISE AND LAST FOR A COUPLE OF HOURS. STRATUS SHOULD ERODE BY MID
TO LATE MORNING, WITH VFR CONDITIONS EXPECTED FOR THE AFTERNOON.
ANOTHER CLOUDY NIGHT SHOULD BE ON TAP, LIKELY FILTERING IN BETWEEN 2-
6Z BASED ON THE MODELS. TRENDED TOWARDS WHAT HAS HAPPENED THE PAST
FEW DAYS GIVEN THE MARINE LAYER LOOKS TO HAVE A SIMILAR DEPTH.
MARINE
(TODAY THROUGH THURSDAY)
ISSUED AT 242 AM PDT SAT MAY 23 2026
MODERATE TO STRONG NORTHERLY BREEZES WILL GRADUALLY DECREASE THIS
MORNING OVER THE NORTHERN OUTER WATERS ALLOWING ROUGH SEAS TO
GRADUALLY SUBSIDE AS WELL. CONDITIONS REMAIN HAZARDOUS FOR SMALL
CRAFTS IN THE AFOREMENTIONED AREA THROUGH 9AM SATURDAY MORNING.
ELSEWHERE, WEST TO SOUTHWESTERLY WINDS WILL REMAIN LIGHT TO GENTLE
WITH MODERATE WAVE HEIGHTS. SEAS ABATE TO MODERATE HEIGHTS BY
MIDDAY SATURDAY AND THEN HOLD THROUGH EARLY TUESDAY MORNING. AN
INCOMING TROUGH IS SET TO APPROACH OUR WATERS LATE MONDAY NIGHT,
BRINGING STRONG NORTHWESTERLY WINDS AND BUILDING ROUGH SEAS.
MTR WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 9 AM PDT THIS MORNING FOR PT ARENA TO
PT REYES 10-60 NM.
SHORT TERM...DIALH
LONG TERM....DIALH
AVIATION...KR
MARINE...KR
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