980
FXUS66 KMTR 270503
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
1003 PM PDT THU JUN 26 2025
..NEW AVIATION, MARINE
SYNOPSIS
ISSUED AT 157 PM PDT THU JUN 26 2025
AN INLAND WARMING TREND FRIDAY AND SATURDAY AS HIGH PRESSURE
BUILDS AND THE MARINE LAYER COMPRESSES. BY SUNDAY A WEAK LOW OFF
THE COAST WILL BRING STRONGER ONSHORE FLOW AND DEEPEN THE MARINE
LAYER. THE LOW WILL KEEP TEMPERATURES ON THE COOL SIDE OF NORMAL,
ESPECIALLY INLAND WITH A CONTINUED MARINE LAYER ALONG THE COAST.
UPDATE
ISSUED AT 848 PM PDT THU JUN 26 2025
EVENING SATELLITE AND SURFACE OBSERVATIONS INDICATE AN ON TRACK
FORECAST. THE PREVIOUS DISCUSSION BY RW IS A SOLID LOOK AT THE
DAYS AHEAD. FOR THIS UPDATE, LET'S TALK ABOUT TONIGHT. A WEAK
SURFACE TROUGH OVER THE NORTHERN CALIFORNIA IS SETTING UP A WEAK
OFFSHORE GRADIENT WHICH WILL YIELD SOME OFFSHORE WINDS ACROSS THE
SERVICE AREA, ESPECIALLY OVER THE VACA AND MAYACAMA RANGES. PEAK
WINDS OUT OF THE NE SHOULD ONLY TOP OUT AT ABOUT 25 MPH ALONG THE
HIGHEST PEAKS AND RIDGES IN THE PRE-DAWN HOURS. THAT SAID, THIS
WILL CAUSE HUMIDITY VALUES TO NOT RECOVER AS MUCH AS LOWER
ELEVATIONS IN THE MARINE LAYER. FOR EXAMPLE, LOOK FOR MT ST HELENA
TO STRUGGLE TO REACH 50% RH FOR MAX RECOVERY. ON TOP OF THE
WARMING TREND THAT RW TALKED ABOUT BELOW, THIS WILL CAUSE
CONTINUED DRYING OF FUELS ABOVE ABOUT 1500 FEET, EVEN OVERNIGHT.
MIN TEMPS THE NEXT COUPLE NIGHTS WILL BE CHALLENGED TO DROP BELOW
60F. SO IF YOU LIVE ABOVE THE MARINE LAYER THE NEXT COUPLE NIGHTS,
IT'S GONNA BE ON THE WARMER SIDE.
SHORT TERM
(THIS EVENING THROUGH FRIDAY)
ISSUED AT 157 PM PDT THU JUN 26 2025
SEASONAL WEATHER PATTERN CONTINUES THIS AFTERNOON WITH SUNNY AND
WARM WEATHER INLAND WHILE A 1200 FOOT MARINE LAYER PERSISTS ALONG
THE COAST WITH TEMPS STILL HOVERING IN THE UPPER 50S AND LOWER
60S. STILL NOT SEEING ANY REAL HOT TEMPS INLAND WITH LOWER 90S
CONFINED TO INTERIOR MONTEREY COUNTY. NORTHERLY GRADIENT FROM
SFO-ACV IS NOW IN EXCESS OF 4 MB WITH LESS STRATUS OFF THE SONOMA
COAST. EXPECT THE SHALLOW MARINE LAYER TO SLOWLY REORGANIZE THIS
EVENING AND SPREAD INTO THE COASTAL VALLEYS OVERNIGHT.
BUILDING SHORTWAVE TYPE RIDGE FOR FRIDAY WILL CONTINUE TO COMPRESS
THE MARINE LAYER AND LEAD TO AN INLAND WARMING TREND FRIDAY
AFTERNOON. EXPECT TO SEE LOWER 90S FOR THE INTERIOR
NORTH/SOUTH/EAST BAY FOR THE FIRST TIME THIS WEEK. MICROCLIMATES
SHOULD BE IN FULL EFFECT WITH TEMPS RANGING FROM 60 AT OCEAN BEACH
TO AROUND 95 FOR THE INTERIOR VALLEYS. IT'LL FINALLY FEEL A
LITTLE MORE SUMMER LIKE INLAND FRIDAY AFTERNOON.
LONG TERM
(FRIDAY NIGHT THROUGH NEXT WEDNESDAY)
ISSUED AT 157 PM PDT THU JUN 26 2025
NO BIG CHANGES INTO SATURDAY WITH THE RIDGE, SO EXPECT A SHALLOW
MARINE LAYER AND ANOTHER DAY OF INLAND TEMPS IN THE 90S BUT THE
COAST AND BAYS WILL REMAIN MILD TO WARM WITH TEMPS RUNNING NEAR
NORMAL.
BY SATURDAY NIGHT INTO SUNDAY THE MODELS ARE COMING INTO AGREEMENT
THAT A WEAK LOW WILL SPIN UP OFFSHORE, WEST OF SAN FRANCISCO. THIS
WILL LIKELY INDUCE A STRONGER SOUTHWESTERLY ONSHORE WIND PATTERN
ON SUNDAY (KIND OF LIKE A MODIFIED SOUTHERLY SURGE). IN ADDITION
THE UPPER LOW WILL LIKELY DEEPEN THE MARINE LAYER. THEREFORE
EXPECT A NOTED COOLING TREND FOR SUNDAY, ESPECIALLY PLACES LIKE
SANTA CRUZ (NORTH SIDE OF MONTEREY BAY), NAPA AND SONOMA VALLEYS
WHERE SOUTHWESTERLY ONSHORE PUSH WILL BE EFFICIENT FOR PUSHING UP
THOSE VALLEYS.
WORTH NOTING THAT ON SUNDAY NIGHT THE UPPER FLOW TURNS
SOUTHEASTERLY ACROSS NORCAL. GFS MUCAPE SHOWS A FEW 100 J/KG BUT
IT DOESNT ALIGN WITH MOISTURE. BEST FORECAST KEEPS T-STORMS WELL
TO OUR NORTH AND EAST BUT WILL MONITOR CLOSELY AS IT DEPENDS ON
EXACT LOCATION OF UPPER LOW. USUAL SCENARIO WITH THESE SETUPS
WOULD BE CONVECTION OVER THE NORTHERN SIERRA AND THE COASTAL
RANGES FROM MENDOCINO NORTHWARD.
THE UPPER LOW LOOKS TO TAKE UP RESIDENCE FOR MUCH OF NEXT WEEK PER
THE LATEST LONG RANGE MODELS. THAT WOULD MEAN TEMPS RUNNING NEAR
TO A FEW DEGREES BELOW NORMAL FOR LATE JUNE/EARLY JULY WITH A
FAIRLY DEEP MARINE LAYER. THUS AS WE HEAD TOWARDS 4TH OF JULY NOT
SEEING ANY ABNORMALLY HOT WEATHER FOR THE BAY AREA WITH ANY PRECIP
LIKELY STAYING OVER THE SIERRA AND SOUTHERN DESERTS AS MONSOON
MOISTURE SLOWLY STARTS TO EJECT OUT OF AZ AND MEXICO.
AVIATION
(06Z TAFS)
ISSUED AT 1003 PM PDT THU JUN 26 2025
PATCHY STRATUS ALONG THE COAST IS EXPECTED TO SPREAD INLAND ACROSS
PORTIONS OF THE BAY AREA OVERNIGHT. MODERATE CONFIDENCE THAT STRATUS
WILL REACH SFO, OAK, AND APC OVERNIGHT WITH HIGH CONFIDENCE IN
STRATUS AT HAF, MRY, AND SNS. THE MARINE LAYER HAS DEEPENED TO
AROUND 1500 FT WHICH SHOULD HELP KEEP CIGS ON THE MVFR-IFR BORDER
BUT THERE EXISTS SOME POTENTIAL FOR LIFR CIGS TO DEVELOP ALONG THE
COASTLINE. WINDS GENERALLY STAY ONSHORE THROUGH THE TAF PERIOD WITH
BREEZIER WINDS DURING THE AFTERNOON/EVENING AND LIGHTER, VARIABLE AT
TIMES WINDS OVERNIGHT.
VICINITY OF SFO...STRATUS IS EXPECTED TO FILTER IN TO THE SF BAY
OVERNIGHT WITH STRATUS REACHING SFO AROUND 08Z. THIS LEANS SLIGHTLY
ON THE EARLIER SIDE WITH PROBABILISTIC GUIDANCE SUGGESTING STRATUS
MAY COME IN MORE PERMANENTLY AROUND 12Z (COMPARED TO SLIGHTLY
PATCHIER PRIOR TO THAT). CIGS SHOULD STAY ON THE MVFR-IFR BORDER
WITH CURRENT THINKING LEANING MORE TOWARDS MVFR CONDITIONS. CIGS
LOOK TO CLEAR BY MID TO LATE MORNING WITH BREEZY ONSHORE WINDS
CONTINUING DURING THE AFTERNOON/EVENING HOURS.
SFO BRIDGE APPROACH...SIMILAR TO SFO.
MONTEREY BAY TERMINALS...MVFR TO LIFR CIGS ARE EXPECTED OVERNIGHT
WITH HIGHEST CONFIDENCE IN LIFR CIGS DEVELOPING AT MRY. CIGS ARE
CURRENTLY PATCHY IN THE VICINITY OF SNS BUT ARE EXPECTED TO FILL IN
AS STRATUS COVERAGE EXPANDS OVERNIGHT. CIGS WILL GENERALLY CLEAR BY
MID TO LATE MORNING BEFORE RETURNING DURING THE EARLY EVENING HOURS
AT MRY. GUIDANCE INDICATES CIGS COULD RETURN TO SNS TOWARDS THE END
OF THIS TAF PERIOD BUT CONFIDENCE IS LOW THAT CIGS WILL RETURN PRIOR
TO 06Z. MODERATE ONSHORE WINDS ARE EXPECTED DURING THE
AFTERNOON/EVENING HOURS BEFORE WINDS EASE OVERNIGHT.
MARINE
(TONIGHT THROUGH NEXT WEDNESDAY)
ISSUED AT 1003 PM PDT THU JUN 26 2025
STRONG TO NEAR GALE FORCE WINDS CONTINUE OVER THE COASTAL WATERS
WITH GALE FORCE WINDS CONTINUING ALONG THE BIG SUR COASTLINE.
WINDS DIMINISH ACROSS THE INNER WATERS BY FRIDAY AFTERNOON AND
PORTIONS OF THE OUTER COASTAL WATERS BY SATURDAY. FRESH TO STRONG
WINDS WILL CONTINUE OVER THE OUTER WATERS NORTH OF POINT REYES
THROUGH SUNDAY. MODERATE TO ROUGH SEAS CONTINUE THROUGH FRIDAY
WITH SIGNIFICANT WAVE HEIGHTS TO SUBSIDE SATURDAY INTO SUNDAY AS
WINDS EASE. THE NEXT ROUND OF ELEVATED WAVE HEIGHTS, STRONG
NORTHWESTERLY WINDS, AND MODERATE TO ROUGH SEAS BEGINS TUESDAY
AND CONTINUES THROUGH LATE NEXT WEEK.
MTR WATCHES/WARNINGS/ADVISORIES
CA...COASTAL FLOOD ADVISORY UNTIL 2 AM PDT FRIDAY FOR CAZ006-506-508.
PZ...SMALL CRAFT ADVISORY UNTIL 3 AM PDT SATURDAY FOR PIGEON PT TO PT
PINOS 10-60 NM-PT ARENA TO PT REYES 0-10 NM-PT ARENA TO PT
REYES 10-60 NM.
SMALL CRAFT ADVISORY UNTIL 3 AM PDT FRIDAY FOR PIGEON PT TO PT
PINOS 0-10 NM-PT REYES TO PIGEON PT 0-10 NM.
GALE WARNING UNTIL 3 AM PDT FRIDAY FOR PT PINOS TO PT PIEDRAS
BLANCAS 0-10 NM.
SHORT TERM...RW
LONG TERM....RW
AVIATION...KENNEDY
MARINE...KENNEDY
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