512
FXUS66 KMTR 311203
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
503 AM PDT SAT MAY 31 2025
..NEW AVIATION
SYNOPSIS
ISSUED AT 355 AM PDT SAT MAY 31 2025
HAZARDOUS HEAT IS EXPECTED AGAIN TODAY ALONG WITH ELEVATED FIRE
WEATHER CONDITIONS. A PATTERN CHANGE BEGINS ON SUNDAY, LEADING TO
COOLER WEATHERS FOLLOWED BY MORE SEASONAL TEMPERATURES NEXT WEEK.
SHORT TERM
(TODAY AND TONIGHT)
ISSUED AT 355 AM PDT SAT MAY 31 2025
KEY MESSAGES
-MODERATE HEATRISK FOR FAR INTERIOR LOCATIONS AND THE SANTA CLARA
VALLEY, WHICH IS WHERE A HEAT ADVISORY WILL GO INTO EFFECT LATER
TODAY.
-ELEVATED FIRE WEATHER CONCERNS TODAY.
-NON-ZERO CHANCE FOR HIGH-BASED CONVECTION SATURDAY
STRATUS IS NOT AS WIDESPREAD THIS MORNING WITH THE NARROW RIBBON
STARTING ALONG THE MARIN COAST AND SPANNING DOWN OUR CENTRAL COAST.
EXPECT ANY INTERIOR LOCATIONS IMPACTED BY STRATUS OR FOG TO MIX OUT
BY MID TO LATE MORNING. HIGH TEMPERATURES TODAY BEGIN TO MODERATE
SOME AS UPPER LEVEL RIDGING GETS SQUASHED BY A TROUGH TO OUR NORTH
AND A CUT OFF LOW TO OUR SOUTH. HIGH TEMPERATURES THIS AFTERNOON
LOOK TO BE ABOUT 5 TO 15 DEGREES ABOVE NORMAL, WHERE FAR INTERIOR
LOCATIONS COULD REACH THE UPPER 90S TO AROUND 100 DEGREES. THE
SPREAD FOR TODAY WILL BE MUCH LIKE YESTERDAY, AS THE COAST WILL HAVE
THE NATURAL AC GOING FOR IT AGAIN. ANOTHER DAY OF ELEVATED FIRE
WEATHER CONCERNS ARE ON TAP AS, RH VALUES LOOK TO BE ON THE LOWER
END AGAIN WITH ANOTHER NIGHT OF POOR TO MODERATE RECOVERY FOR THE
HIGHER POINTS OF TERRAIN. THE FINAL NOTE FOR SATURDAY IS THE
CONTINUED LOW END THREAT FOR CONVECTION, WHICH REMAINS BELOW 10%.
LIMITING FACTORS WILL BE CAPE (INSTABILITY/ENERGY) AND MOISTURE, DUE
TO THE UPPER LEVEL RIDGE IN PLACE. EXPECT TO POTENTIALLY SEE SOME
CUMULUS POTENTIALLY POP UP OVER OUR TERRAIN, FAVORING MONTEREY AND
SAN BENITO COUNTIES, BUT THERE COULD ALONG THE DIABLO RANGE AND INTO
THE INTERIOR NORTH BAY MOUNTAINS. THE BEST CHANCE FOR ELEVATED
THUNDERSTORMS LOOKS TO BE IN MONTEREY/SAN BENITO AREAS IF IT DOES
OCCUR.
LONG TERM
(SUNDAY THROUGH FRIDAY)
ISSUED AT 355 AM PDT SAT MAY 31 2025
KEY MESSAGES
-PATTERN CHANGE AND COOL DOWN ON SUNDAY
-MARINE LAYER RETURNS, MORE SEASONAL WEATHER NEXT WEEK
HIGH PRESSURE IS OUT OF THE PICTURE BY SUNDAY AS THE CUTOFF LOW TO
OUR SOUTH NUDGES NORTH AND EASTWARD, AND TROUGHING SAGS INTO NORCAL.
THIS WILL BRING A REPRIEVE IN TEMPERATURES DROPPING US EITHER NEAR
NORMAL TO 10 DEGREES BELOW NORMAL FOR THIS TIME OF YEAR. BY LATE
SUNDAY INTO MONDAY, THE SOUTHERN CUTOFF LOW ADVANCES EAST WHILE THE
TROUGH TO OUR NORTH CUTS OFF AND THEN SLIDES TOWARDS DOWN THE CA
COAST MONDAY AND MAKES IT TO SOCAL BY TUESDAY. THE SIGNAL FOR IT
RETROGRADING SOME ON MONDAY DOESN'T APPEAR IN THE LATEST GUIDANCE,
BUT IT WILL BE SOMETHING TO KEEP AN EYE ON. OUTSIDE OF THAT, THE
MARINE LAYER LOOKS WHICH COULD BRING SOME FOG AND COASTAL DRIZZLE.
LOOK FOR TEMPERATURES TO GRADUALLY RETURN TO NEAR NORMAL THROUGH
THE WEEK.
AVIATION
(12Z TAFS)
ISSUED AT 502 AM PDT SAT MAY 31 2025
LIFR CIGS AND FOG CONTINUE ALONG THE COASTLINE. FOG IS MOST LIKELY
ALONG THE MONTEREY BAY COASTLINE WITH A SLIGHTLY LOWER LIKELIHOOD
FARTHER NORTH AT HAF. CIGS ARE EXPECTED TO STAY CONFINED TO THE
COASTLINE BUT SOME TEMPORARY FOG/LOWERED VISIBILITIES MAY DEVELOP IN
THE VICINITY OF STS AND APC BETWEEN 12Z TO 16Z. CIGS START TO
IMPROVE ALONG THE COAST BETWEEN 16Z TO 18Z WITH CLEARING EXPECTED
AFTER 18Z. LOCALLY BREEZY WINDS DEVELOP DURING THE DAY BEFORE EASING
SLIGHTLY OVERNIGHT. CIGS LOOK TO RETURN EARLY TOMORROW EVENING ALONG
THE COASTLINE. CONFIDENCE IS LOW AS TO IF CIGS WILL RETURN TO
INTERIOR AIRPORTS WITH A SLIGHTLY DEEPER MARINE LAYER (AROUND 1000
FT) POTENTIALLY ALLOW STRATUS TO EXTEND INTO THE SF BAY TOMORROW
NIGHT.
VICINITY OF SFO...VFR THROUGH TOMORROW NIGHT WITH LOW TO MODERATE
CONFIDENCE IN MVFR CIGS RETURNING. MODERATE WEST TO NORTHWEST WINDS
CONTINUE THROUGH THE MAJORITY OF THE TAF PERIOD WITH GUSTS TO AROUND
24 KNOTS EXPECTED DURING THE AFTERNOON/EVENING. LOW TO MODERATE
CONFIDENCE THAT STRATUS WILL REACH SFO TOMORROW NIGHT WITH CURRENT
THINKING SUPPORTING MVFR CIGS CONTINUING THROUGH THE END OF THE TAF
PERIOD.
SFO BRIDGE APPROACH...SIMILAR TO SFO.
MONTEREY BAY TERMINALS...FOG AND LIFR CONDITIONS CONTINUE THROUGH AT
LEAST 16Z. WENT SLIGHTLY MORE OPTIMISTIC WITH CIGS AND VIS STARTING
TO IMPROVE AROUND 16Z BEFORE CLEARING FULLY AROUND 18Z. CURRENT
THINKING SUPPORTS STRATUS AND FOG RETURNING AGAIN TOMORROW NIGHT
WITH STRATUS ARRIVING DURING THE EVENING AND FOG DEVELOPING
OVERNIGHT. MODERATE NORTHWEST WINDS CONTINUE DURING THE DAY BEFORE
WINDS EASE OVERNIGHT.
MARINE
(TODAY THROUGH THURSDAY)
ISSUED AT 355 AM PDT SAT MAY 31 2025
BREEZY TO GUSTY CONDITIONS CONTINUE OVER THE NORTHERN COASTAL
WATERS RESULTING IN STEEP WIND WAVES AND HAZARDOUS CONDITIONS FOR
SMALL CRAFTS. WINDS STRENGTHEN STARTING LATE SATURDAY INTO SUNDAY
WITH GALE FORCE GUSTS EXPECTED OVER THE NORTHERN COASTAL WATERS
AND STRONG GUSTS ACROSS THE SOUTHERN OUTER WATERS. ROUGH SEAS ARE
EXPECTED ACROSS THE OUTER WATERS LATE SATURDAY WITH SIGNIFICANT
WAVE HEIGHTS 10 TO 15 FEET ACROSS THE SOUTHERN OUTER WATERS AND UP
TO 22 FEET ACROSS THE NORTHERN OUTER WATERS. WINDS GRADUALLY EASE
BY TUESDAY BUT SIGNIFICANT WAVE HEIGHTS WILL REMAIN ELEVATED
THROUGH MID TO LATE WEEK.
FIRE WEATHER
ISSUED AT 355 AM PDT SAT MAY 31 2025
ELEVATED FIRE WEATHER CONCERNS WILL PERSIST TODAY. THE MARINE
LAYER IS COMPRESSED TO NEAR SEA LEVEL, WITH HIGHER ELEVATIONS
REMAINING DRY WITH MODERATE TO LOCALLY POOR HUMIDITY RECOVERY
TONIGHT. DAYTIME REMAIN ELEVATED FOR FAR INTERIOR LOCATIONS,
WHILE OTHER AREAS MODERATE SOME. COOLER WEATHER ARRIVES SUNDAY.
PEOPLE SHOULD BE MINDFUL TO AVOID ACTIVITIES THAT COULD SPARK A
GRASS FIRE.
CLIMATE
ISSUED AT 1128 PM PDT TUE MAY 27 2025
RECORD HIGH TEMPERATURES AT THE LONG TERM CLIMATE STATIONS
SATURDAY, MAY 31ST.
STATION MAY 31ST
SANTA ROSA 99F 1970
KENTFIELD 102F 2001
NAPA 103F 2001
RICHMOND 95F 2001
LIVERMORE 104F 2001, 1910
SAN FRANCISCO 90F 2001
SFO AIRPORT 91F 2001
REDWOOD CITY 99F 2001
HALF MOON BAY 77F 1997
OAKLAND DOWNTOWN 89F 2001
SAN JOSE 98F 1970
SALINAS AIRPORT 90F 1997
KING CITY 100F 2001
MTR WATCHES/WARNINGS/ADVISORIES
CA...HEAT ADVISORY FROM 11 AM THIS MORNING TO 8 PM PDT THIS EVENING
FOR CAZ504-510-513-516>518.
DENSE FOG ADVISORY UNTIL 10 AM PDT THIS MORNING FOR CAZ509-
528>530.
PZ...SMALL CRAFT ADVISORY FROM 9 PM THIS EVENING TO 3 AM PDT SUNDAY
FOR SF BAY N OF BAY BRIDGE.
DENSE FOG ADVISORY UNTIL 10 AM PDT THIS MORNING FOR MRY BAY-
PIGEON PT TO PT PINOS 0-10 NM-PT PINOS TO PT PIEDRAS
BLANCAS 0-10 NM.
SMALL CRAFT ADVISORY UNTIL 3 PM PDT THIS AFTERNOON FOR PT ARENA
TO PT REYES 0-10 NM-PT ARENA TO PT REYES 10-60 NM.
GALE WARNING FROM 3 PM THIS AFTERNOON TO 3 AM PDT SUNDAY FOR PT
ARENA TO PT REYES 0-10 NM.
SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO 3 AM PDT SUNDAY
FOR PT REYES TO PIGEON PT 0-10 NM.
GALE WARNING FROM 3 PM THIS AFTERNOON TO 3 PM PDT SUNDAY FOR PT
ARENA TO PT REYES 10-60 NM.
SMALL CRAFT ADVISORY UNTIL 3 PM PDT SUNDAY FOR PIGEON PT TO PT
PINOS 10-60 NM.
SHORT TERM...KR
LONG TERM....KR
AVIATION...KENNEDY
MARINE...KENNEDY
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