928
FXUS66 KMTR 192038
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
138 PM PDT SAT JUL 19 2025
..NEW SHORT TERM, LONG TERM, MARINE
KEY MESSAGES
UPDATED AT 133 PM PDT SAT JUL 19 2025
- COOLING TREND BEGINS MONDAY WITH A WIDESPREAD RETURN TO BELOW
NORMAL TEMPERATURES.
- LOCALIZED ELEVATED FIRE WEATHER THREAT FOR THE EAST BAY HILLS
SUNDAY AND MONDAY DUE TO DRY CONDITIONS AND GUSTY WINDS.
- GUSTY WINDS RETURN LATE SUNDAY AND CONTINUE THROUGH MONDAY
ALONG THE COAST, THE HIGHER TERRAIN, AND MOUNTAIN GAPS/PASSES.
SHORT TERM
ISSUED AT 133 PM PDT SAT JUL 19 2025
(THIS EVENING THROUGH SUNDAY)
STRATUS IS DISSIPATING MORE SLOWLY ACROSS THE INTERIOR TODAY THAN IT
DID YESTERDAY WITH STRATUS YET TO CLEAR OUT OF THE SAN FRANCISCO BAY
AND BAY SHORELINE REGIONS. A LOOK AT THE 24 HOUR TEMPERATURE CHANGE
SHOWS THAT MOST LOCATIONS ACROSS THE BAY AREA (OUTSIDE OF THE HIGHER
ELEVATIONS) ARE RUNNING SEVERAL DEGREES COOLER TODAY THAN THEY WERE
AT THIS TIME YESTERDAY. YESTERDAY'S HIGH TEMPERATURES PEAKED 1-2
DEGREES BELOW WHAT IT WAS FORECAST TO REACH. THERE IS THE POTENTIAL
THAT TODAY'S HIGHS WILL BE LOWER THAN WHAT IS CURRENTLY FORECAST
GIVEN THE PROLONGED STRATUS COVERAGE AND OBSERVED TEMPERATURES
TRENDING COOLER. THIS DOESN'T CHANGE THE OVERALL FORECAST TOO MUCH,
HIGH TEMPERATURES ARE GENERALLY EXPECTED TO STAY IN THE UPPER 70S TO
80S WITH THE MOST INTERIOR AREAS REACHING THE 90S. THE INTERIOR
CENTRAL COAST IS LIKELY TO REACH THE UPPER 90S BUT CONFIDENCE IS
DECREASING THAT HIGH TEMPERATURES WILL BREAK 100.
SATURDAY NIGHT INTO SUNDAY, STRATUS IS EXPECTED TO BUILD BACK IN
ACROSS THE INTERIOR WITH THE MARINE LAYER STAYING BETWEEN 1200 FT TO
1500 FT. THIS WILL RESULT IN SOME POTENTIAL FOR DRIZZLE AND FOG
ALONG THE COASTLINE EARLY SUNDAY MORNING. SLIGHTLY WARMER
TEMPERATURES (COMPARED TO EARLIER THIS WEEK) WILL CONTINUE INTO
SUNDAY WITH HIGH TEMPERATURES EXPECTED TO BE IN THE UPPER 70S TO LOW
90S ACROSS THE INTERIOR. TEMPERATURES ACROSS THE FAR INTERIOR
CENTRAL COAST WILL STILL BE IN THE MID TO UPPER 90S, BUT, MOST SITES
WILL BE AT LEAST 1-2 DEGREES COOLER ON SUNDAY THAN ON SATURDAY.
SUNDAY WILL BE THE LAST DAY OF AT LEAST CLOSER TO SEASONAL
TEMPERATURES WITH AN UPPER LEVEL TROUGH SET TO MOVE SOUTHWARD INTO
CALIFORNIA BY LATE SUNDAY. THIS TROUGH WILL ALLOW THE MARINE LAYER
TO DEEPEN TO 1500 TO 2000 FT BY SUNDAY NIGHT WITH STRATUS RETURNING
ACROSS THE MAJORITY OF THE BAY AREA AND CENTRAL COAST. THE ARRIVAL
OF THIS TROUGH WILL ADDITIONALLY BRING GUSTY ONSHORE (SOUTHWEST TO
WEST) WINDS ALONG THE COAST, SAN PABLO/SUISUN BAY AND THE DELTA,
MOUNTAIN RIDGETOPS, AND MOUNTAIN GAPS/PASSES. THE STRONGEST WINDS
WILL BE OVER THE EAST BAY HILLS AND OVER THE EASTERN MOST PORTIONS
OF ALAMEDA AND CONTRA COSTA COUNTIES WHERE WINDS WILL GUST TO AROUND
40 KNOTS. AREAS THAT TYPICALLY EXPERIENCE TERRAIN FUNNELING (E.G.
ALTAMONT PASS) MAY SEE THE OCCASIONAL LOCALLY STRONGER GUST SUNDAY
EVENING/NIGHT. SIMILAR TO WHAT THE PREVIOUS FORECASTER STATED, WINDS
IN THE EAST BAY HILLS/VALLEY WILL PEAK AROUND WIND ADVISORY CRITERIA
BUT DO NOT LAST LONG ENOUGH IN DURATION FOR A WIND ADVISORY TO BE
ISSUED.
FIRE WEATHER CONCERNS WILL BE ELEVATED FOR THE EAST BAY HILLS
STARTING SUNDAY AFTERNOON THROUGH THE END OF THE SHORT TERM
FORECAST. DAYTIME CONDITIONS WILL BE DRY, WITH HUMIDITY VALUES
DROPPING TO AROUND 35 TO 40%. FORTUNATELY, THE STRONGEST WINDS ARE
EXPECTED TO DEVELOP AS THE SUN IS GOING DOWN AND HUMIDITY VALUES
START TO RISE. AS THE MARINE LAYER EXPANDS, THIS REGION IS
ANTICIPATED TO HAVE GOOD OVERNIGHT HUMIDITY RECOVERIES PEAKING
AROUND 80 TO 85%. IN ADDITION, 100 HOUR FUELS REMAIN FAIRLY MOIST IN
THIS AREA IN PART THANKS TO THE COOLER TEMPERATURES AND DEEP MARINE
LAYER THAT WE HAVE SEEN SO FAR THIS SUMMER. BOTH OF THESE FACTORS
WILL HELP TO SOMEWHAT MITIGATE CONCERNS, BUT, FIRE WEATHER CONCERNS
WILL REMAIN ELEVATED GIVEN HOW GUSTY THE WINDS ARE FORECAST TO BE
AND THE DRY DAYTIME CONDITIONS.
LONG TERM
ISSUED AT 133 PM PDT SAT JUL 19 2025
(SUNDAY NIGHT THROUGH NEXT FRIDAY)
GUSTY ONSHORE WINDS WILL CONTINUE ALONG THE COAST, SAN PABLO/SUISUN
BAY AND THE DELTA, MOUNTAIN RIDGETOPS, AND MOUNTAIN GAPS/PASSES
THROUGH EARLY TUESDAY MORNING. WINDS BRIEFLY EASE MONDAY
MORNING/EARLY AFTERNOON BEFORE ANOTHER ROUND OF STRONGER WINDS
RETURN DURING THE EVENING/OVERNIGHT HOURS. GUSTS WILL PEAK AROUND
40 MPH BUT OCCASIONAL STRONGER GUSTS TO 45 MPH ARE POSSIBLE. WINDS
WILL REMAIN BREEZY THROUGH THE REMAINDER OF MONDAY NIGHT INTO
TUESDAY BEFORE DIMINISHING BY LATE TUESDAY MORNING. FIRE WEATHER
CONCERNS, AS OUTLINED IN THE SHORT TERM, WILL REMAIN ELEVATED FOR
THE EAST BAY HILLS AND VALLEYS THROUGHOUT THE DAY ON MONDAY BEFORE
DIMINISHING TUESDAY MORNING.
OTHERWISE, THE RETURN OF UPPER LEVEL TROUGHING WILL GIVE US A RINSE
AND REPEAT OF WHAT WE SAW FOR MUCH OF THE PREVIOUS WEEK: DEEP MARINE
LAYER, WIDESPREAD OVERCAST CONDITIONS RETURNING EACH NIGHT, AND
BELOW NORMAL TEMPERATURES. HIGH TEMPERATURES ACROSS THE ELEVATED
TERRAIN WILL DROP AS MUCH AS TEN DEGREES BETWEEN SUNDAY AND MONDAY
WITH HIGHS IN THE UPPER 70S TO LOW 80S ACROSS THE INTERIOR.
TEMPERATURES ACROSS THE INTERIOR CENTRAL COAST WILL REMAIN WARMER IN
THE UPPER 80S TO LOW 90S WHILE COASTAL AREAS STAY COOL IN THE UPPER
50S TO MID 60S. DIURNALLY BREEZY AFTERNOON WINDS WILL RETURN TUESDAY
THROUGH THE END OF THE FORECAST PERIOD ALONG THE COAST, MOUNTAIN
GAPS/PASSES, AND RIDGETOPS WITH GUSTS BETWEEN 20 TO 30 MPH EXPECTED.
ELEVATED FIRE WEATHER THREAT CONTINUES ACROSS THE HIGHER TERRAIN DUE
TO DRY DAYTIME CONDITIONS AND POOR OVERNIGHT HUMIDITY RECOVERIES.
AVIATION
(18Z TAFS)
ISSUED AT 1043 AM PDT SAT JUL 19 2025
IFR AT COASTAL SITES AND NORTH BAY SITES THIS MORNING WHILE MVFR
PERSIST ACROSS THE BAY AREA TERMINALS. CONDITIONS WILL RETURN TO VFR
BY AROUND 18Z-20Z THIS AFTERNOON FOR MOST INLAND TAF, WITH THE
EXCEPTION OF HAF WHERE IFR/MVFR CONDITIONS LOOK TO PERSIST THROUGH
MUCH OF THE TAF PERIOD. ONSHORE WINDS INCREASE THIS AFTERNOON BEFORE
EASING AFTER SUNSET. RATHER HIGH CONFIDENCE FOR MVFR CONDITIONS TO
RETURN THIS EVENING BEFORE LOWERING TO IFR BY LATE EVENING AND INTO
SUNDAY MORNING. THE GREATEST POTENTIAL FOR LIFR CONDITIONS WILL BE
ACROSS THE NORTH BAY AND MONTEREY BAY TERMINALS EARLY SUNDAY MORNING
BEFORE CEILINGS BEGIN TO LIFT BY LATE MORNING. CEILINGS CLEAR OUT BY
18Z-20Z FOR MOST COASTAL SITES WITH EARLIER CLEARING ACROSS THE
INTERIOR TAF SITES. ONSHORE WINDS INCREASE ONCE AGAIN BY SUNDAY
AFTERNOON.
VICINITY OF SFO...IFR CURRENTLY BUT ARE FORECAST TO LIFT TO MVFR
BEFORE CLEARING BETWEEN 18Z-20Z. ONSHORE WINDS INCREASE THIS
AFTERNOON BEFORE EASING AFTER SUNSET. HIGH CONFIDENCE FOR MVFR
CEILINGS TO RETURN THIS EVENING BEFORE LOWERING TO IFR EITHER LATE
TONIGHT OR EARLY SUNDAY MORNING. CONDITIONS RETURN TO VFR BY 18Z-20Z
SUNDAY WITH AN INCREASE IN ONSHORE WINDS BY SUNDAY AFTERNOON.
SFO BRIDGE APPROACH...SIMILAR TO SFO.
MONTEREY BAY TERMINALS...IFR CURRENTLY BUT ARE FORECAST TO LIFT TO
MVFR. LOW CEILINGS WILL SCATTER OUT BY 1930Z-2100Z WITH AN INCREASE
IN ONSHORE WINDS THIS AFTERNOON. HIGH CONFIDENCE FOR EARLY RETURN OF
MVFR CEILING THIS EVENING BEFORE LOWERING TO IFR LATE THIS EVENING
OR EARLY SUNDAY MORNING. GREATEST PROBABILITY FOR LIFR CONDITIONS
EARLY SUNDAY MORNING AT MRY.
MARINE
(TONIGHT THROUGH NEXT THURSDAY)
ISSUED AT 133 PM PDT SAT JUL 19 2025
LIGHT TO MODERATE NORTHWESTERLY BREEZES WILL CONTINUE ACROSS MUCH
OF THE COASTAL WATERS THROUGH SATURDAY NIGHT. GUSTY WINDS,
POTENTIALLY HAZARDOUS TO SMALL CRAFT, ALSO DEVELOP EACH AFTERNOON
AND EVENING THROUGH THE GOLDEN GATE, INTO THE DELTA, AND THE
FAVORED COASTAL JETS OFF OF PIGEON POINT AND THE BIG SUR
COASTLINES. WINDS WILL INCREASE SLIGHTLY ON SUNDAY BEFORE EASING
INTO NEXT WEEK. SLIGHT TO MODERATE SEAS PERSIST THROUGH THE
REMAINDER OF THE FORECAST PERIOD.
MTR WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 9 PM PDT THIS EVENING FOR SF BAY N OF
BAY BRIDGE.
SMALL CRAFT ADVISORY FROM 9 AM SUNDAY TO 3 AM PDT MONDAY FOR PT
ARENA TO PT REYES 0-10 NM-SF BAY N OF BAY BRIDGE.
SMALL CRAFT ADVISORY UNTIL 9 PM PDT THIS EVENING FOR MRY BAY-
PIGEON PT TO PT PINOS 0-10 NM.
SMALL CRAFT ADVISORY UNTIL 3 AM PDT SUNDAY FOR PT PINOS TO PT
PIEDRAS BLANCAS 0-10 NM.
SMALL CRAFT ADVISORY UNTIL 3 AM PDT MONDAY FOR PT ARENA TO PT
REYES 10-60 NM.
SHORT TERM...KENNEDY
LONG TERM....KENNEDY
AVIATION...RGASS
MARINE...RGASS
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