951
FXUS66 KMTR 210453
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
953 PM PDT SUN JUL 20 2025
..NEW AVIATION
KEY MESSAGES
UPDATED AT 231 PM PDT SUN JUL 20 2025
- BELOW NORMAL TEMPERATURES RETURN MONDAY AND CONTINUE THROUGH
THE END OF NEXT WEEK.
- LOCALIZED ELEVATED FIRE WEATHER THREAT FOR THE EAST BAY HILLS
SUNDAY AND MONDAY DUE TO DRY CONDITIONS AND GUSTY WINDS.
- GUSTY WINDS RETURN LATE TONIGHT AND CONTINUE THROUGH MONDAY
NIGHT ALONG THE COAST, RIDGETOPS, AND MOUNTAIN GAPS/PASSES.
UPDATE
ISSUED AT 821 PM PDT SUN JUL 20 2025
THE FORECAST REMAINS ON TRACK. HIGHER ELEVATIONS IN THE EAST BAY
ARE STARTING TO SEE WINDS AND GUST PICK UP WITH A FEW GUSTS NEAR
50 MPH SO FAR. THESE WINDS LOOK PEAK IN THE NEXT FEW HOURS AND
DECREASE INTO THE EARLY MORNING, BUT WILL BUILD AGAIN TOMORROW
NIGHT. AFTER THAT, THE FORECAST GET LESS EXCITING FOR THE REST OF
THE WORK WEEK.
-MURDOCK
SHORT TERM
ISSUED AT 231 PM PDT SUN JUL 20 2025
(THIS EVENING THROUGH MONDAY)
HIGH PRESSURE ACROSS THE REGION HAS MOSTLY BROKEN DOWN WITH UPPER
LEVEL TROUGHING TO BECOME REESTABLISHED THIS EVENING/OVERNIGHT. AS
TROUGHING BECOMES REESTABLISHED, THE MARINE LAYER WILL START TO
DEEPEN FROM APPROXIMATELY 1500 FT (OBSERVED ON THE 12Z OAK SOUNDING)
TO AROUND 2000 FT BY MIDDAY TOMORROW. THIS WILL ALLOW THE MARINE
LAYER TO PUSH FARTHER INLAND OVERNIGHT WITH STRATUS LIKELY TO MAKE
IT INTO THE BAY AREA VALLEYS. AT THE SAME TIME, HIGH TEMPERATURES
TOMORROW WILL COOL TO WELL BELOW NORMAL WITH TEMPERATURES RUNNING
ANYWHERE FROM 5 DEGREES TO 15 DEGREES COOLER THAN AVERAGE. A FEW OF
THE SITES IN THE HIGHER TERRAIN WILL BE CLOSER TO 20 DEGREES BELOW
NORMAL. THIS WILL RESULT IN TEMPERATURES LARGELY IN THE 70S TO LOW
80S ACROSS THE INTERIOR AND UPPER 50S TO LOW 60S ALONG THE
COASTLINE. THE INTERIOR CENTRAL COAST WILL SEE LOCALLY WARMER
TEMPERATURES IN THE 80S TO LOW 90S. FOR EXAMPLE, THE FORECASTED HIGH
FOR SAN JOSE ON MONDAY IS 75 DEGREES WHILE THE NORMAL HIGH IS 81
DEGREES. THIS PATTERN OF UPPER LEVEL TROUGHING AND COOLER THAN
NORMAL TEMPERATURES IS SET TO CONTINUE THROUGH THE REMAINDER OF THE
LONG TERM FORECAST.
IN ADDITION TO THE RETURN OF BELOW NORMAL TEMPERATURES, ONSHORE
WINDS ARE EXPECTED TO STRENGTHEN ALONG THE COAST, ACROSS MOUNTAIN
RIDGETOPS AND GAPS/PASSES, AND ACROSS THE SAN PABLO/SUISUN BAY AND
DELTA REGION. THIS WILL BRING GUSTS BETWEEN 30 TO 40 MPH ACROSS THE
ABOVE LISTED AREAS WITH HIGHER GUSTS BETWEEN 40 TO 50 MPH POSSIBLE
ACROSS THE EAST BAY HILLS. THE STRONGEST WINDS ARE LIKELY TO BE IN
THE VICINITY OF THE ALTAMONT PASS, AN AREA WHERE TERRAIN FUNNELING
IS COMMON, WITH PROBABILISTIC GUIDANCE SUGGESTING A 10% CHANCE OF
WINDS GUSTING ABOVE 50 MPH. THE AREA OF STRONGEST WINDS WILL
OCCASIONALLY REACH WIND ADVISORY CRITERIA, BUT, THE AREAL EXTENT AND
DURATION IN TIME OF THE WINDS IS TOO SHORT TO NECESSITATE ONE BEING
ISSUED. GUSTY WINDS CONTINUE FROM SUNDAY EVENING THROUGH LATE MONDAY
NIGHT/EARLY TUESDAY MORNING WITH STRONGEST WINDS TAKING PLACE DURING
THE LATE AFTERNOON/EVENING HOURS. SMALL FUELS (E.G. GRASSES) ARE DRY
WITHIN THE EAST BAY HILLS BUT LARGER 100 HOUR FUELS (E.G. SMALLER
TIMBER TYPE VEGETATION)REMAIN FAIRLY MOIST. THIS WILL HELP TO
MITIGATE THE RISK OF LARGER FIRES BUT IF A GRASS FIRE STARTS IN A
FAVORED WIND CORRIDOR IT WILL HAVE THE POTENTIAL TO EXPAND RAPIDLY.
AS SUCH, RESIDENTS OF OR TRAVELERS WITHIN THIS AREA SHOULD EXERCISE
CAUTION IF PARTICIPATING IN ANY OUTDOORS ACTIVITIES INVOLVING FLAMES
(E.G. BARBECUING, CAMPFIRES) AND ENSURE EQUIPMENT IS PROPERLY
SECURED (E.G. TOWING EQUIPMENT) TO PREVENT STRAY SPARKS.
LONG TERM
ISSUED AT 231 PM PDT SUN JUL 20 2025
(MONDAY NIGHT THROUGH NEXT SATURDAY)
GUSTY ONSHORE WINDS WILL CONTINUE THROUGH EARLY TUESDAY MORNING WITH
WINDS CONTINUING TO EASE THROUGHOUT THE REMAINDER OF THE DAY. EXPECT
A RETURN TO OUR TYPICAL DIURNALLY BREEZY PATTERN (GUSTS TO 20 TO 30
MPH) EACH AFTERNOON/EVENING FOR THE COASTLINE AND MOUNTAIN
GAPS/PASSES.
UPPER LEVEL TROUGHING WILL CONTINUE THROUGH THE END OF
THE FORECAST PERIOD WITH BELOW NORMAL TEMPERATURES (70S TO LOW 80S
ACROSS THE INTERIOR AND UPPER 50S TO MID 60S ALONG THE COAST). NO
SKY JULY REMAINS IN FULL SWING WITH WIDESPREAD OVERCAST SKIES,
COASTAL DRIZZLE, AND PATCHY COASTAL FOG TO CONTINUE THIS WEEK. THIS
TROUGH LOOKS TO DEVELOP A CUT-OFF LOW BY MIDWEEK THAT THEN HOVERS
JUST OFFSHORE OF THE BAY AREA. THIS WILL BRING THUNDERSTORM CHANCES
TO OUR NEIGHBORS IN FAR NORTHERN CALIFORNIA AND OREGON, HOWEVER,
THUNDERSTORMS ARE NOT EXPECTED TO DEVELOP WITHIN THE BAY AREA OR IN
THE CENTRAL COAST. ALL IN ALL, NOT TOO MANY CHANGES IN STORE FOR OUR
FORECAST THIS WEEK SO HOPEFULLY YOU HAVE BEEN ENJOYING THE MORE MILD
SUMMER WE HAVE HAD SO FAR.
AVIATION
(06Z TAFS)
ISSUED AT 952 PM PDT SUN JUL 20 2025
MVFR-IFR STRATUS COVERS THE COAST SOUTH OF BODEGA BAY, AND COMES
INLAND INTO THE SONOMA COUNTY VALLEYS, THROUGH THE GOLDEN GATE INTO
THE EAST BAY, AND ACROSS THE MONTEREY BAY, DOWN THE SALINAS VALLEY,
AND INTO THE GILROY-HOLLISTER REGION. STRATUS COVERAGE IS EXPECTED
TO EXPAND THROUGH THE NIGHT WITH MODERATE CONFIDENCE IN STRATUS
IMPACTS IN THE NORTH BAY VALLEYS, SOMEWHAT LOWER AT STS. RECENT
OVERPERFORMANCE OF THE STRATUS LAYERS COMPARED TO MODEL OUTPUT HAS
MADE THE FORECAST RATHER DIFFICULT, BUT THE BEST INDICATION IS THAT
STRATUS WILL RETREAT TO THE IMMEDIATE COASTAL REGION THROUGH MONDAY
MORNING, WITH BREEZY AND GUSTY ONSHORE FLOW DEVELOPING MONDAY
AFTERNOON. LOW CONFIDENCE IN STRATUS CLEARING AT OAK AND MRY AS
ONSHORE FLOW AND A ROBUST MARINE LAYER COULD KEEP CEILINGS AT BOTH
TERMINALS THROUGH THE DAY. STRATUS WILL BEGIN TO DEVELOP INLAND
MONDAY EVENING.
VICINITY OF SFO... MVFR-IFR STRATUS CONTINUES TO IMPACT THE TERMINAL
OVERNIGHT INTO MONDAY MORNING. LOW CONFIDENCE IN STRATUS CLEARING
TIME ACROSS THE TERMINAL AREA AS STRATUS HAS OVERPERFORMED THE
MODELS OVER THE LAST FEW DAYS, BUT EXPECT SEVERAL HOURS OF VFR
CONDITIONS IN THE AFTERNOON. LOWER CONFIDENCE IN CLEARING AT OAK.
BREEZY ONSHORE WINDS RETURN TO THE TERMINAL MONDAY AFTERNOON AND
EVENING, DIMINISHING AS THE STRATUS RETURNS TO THE TERMINAL AREA.
GREATEST CONFIDENCE IS FOR STRATUS TO RETURN TO THE NORTH OF THE
TERMINAL.
SFO BRIDGE APPROACH... LOWER CONFIDENCE IN STRATUS IMPACTS,
WITH LATER ARRIVAL TIMES THAN THE TERMINAL. OTHERWISE SIMILAR TO SFO.
MONTEREY BAY TERMINALS... IFR-LIFR CEILINGS CONTINUE OVERNIGHT.
STRATUS RETREATS TO THE IMMEDIATE COAST LATE MONDAY MORNING WITH
MODERATE TO HIGH CONFIDENCE THAT MRY IS SOCKED IN THROUGH THE END OF
THE TAF PERIOD. BREEZY ONSHORE FLOW RESUMES MONDAY AFTERNOON.
MARINE
(TONIGHT THROUGH NEXT SATURDAY)
ISSUED AT 821 PM PDT SUN JUL 20 2025
MODERATE BREEZES TO NEAR-GALE FORCE GUSTS ARE EXPECTED TONIGHT
INTO MONDAY, RESULTING IN HAZARDOUS BOATING CONDITIONS FOR
SMALLER VESSELS IN THE NORTHERN SAN FRANCISCO AND SAN PABLO BAYS
AND ACROSS THE NORTHERN OUTER WATERS. STRONG BREEZES WILL ALSO
PERSIST INTO THE PRE- DAWN HOURS ON MONDAY ACROSS THE BIG SUR
COASTLINE. SLIGHT TO MODERATE SEAS PERSIST THROUGH THE REMAINDER
OF THE FORECAST PERIOD. WINDS EASE SOME THROUGH TUESDAY, EXCEPT
ACROSS SOUTHERN PORTIONS OF THE BIG SUR COAST, WHERE STRONG
NORTHWEST BREEZES PERSIST. OTHERWISE, REDUCED VISIBILITY SHOULD
BE ANTICIPATED DURING THE MORNING HOURS DUE TO FOG AND DRIZZLE.
MTR WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 9 PM PDT MONDAY FOR SF BAY N OF BAY
BRIDGE.
SMALL CRAFT ADVISORY FROM 3 PM TO 9 PM PDT MONDAY FOR MRY BAY-
PIGEON PT TO PT PINOS 0-10 NM-PT PINOS TO PT PIEDRAS
BLANCAS 0-10 NM.
SMALL CRAFT ADVISORY UNTIL 9 AM PDT MONDAY FOR PT ARENA TO PT
REYES 0-10 NM-PT ARENA TO PT REYES 10-60 NM.
SHORT TERM...KENNEDY
LONG TERM....KENNEDY
AVIATION...DIALH
MARINE...DIALH
VISIT US AT WWW.WEATHER.GOV/SANFRANCISCO
FOLLOW US ON FACEBOOK, X, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
X.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page