815
FXUS66 KMTR 171815
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
1115 AM PDT THU APR 17 2025
..NEW AVIATION
SYNOPSIS
ISSUED AT 313 AM PDT THU APR 17 2025
CLOUDY START TO THE DAY TODAY AS AN UPPER LEVEL DISTURBANCE MOVES
OUT. WARM UP ON THE WAY FOR THE WEEKEND. BREEZY OFFSHORE WINDS FOR
THE INTERIOR MOUNTAINS FRIDAY AND SATURDAY MORNINGS (LOW IMPACT).
QUIET PATTERN WITH TEMPERATURES AROUND SEASONAL NORMALS FROM THE
WEEKEND ONWARD.
SHORT TERM
(TODAY AND TONIGHT)
ISSUED AT 313 AM PDT THU APR 17 2025
FAIR WEATHER TO ROUND OUT THIS WEEK AS WE SAY GOODBYE TO ANY RAIN
CHANCES THAT MAY HAVE ACCOMPANIED THE WEAK UPPER LOW WE'VE BEEN
DEALING WITH THESE PAST COUPLE OF DAYS. CLOUDY START TO THE MORNING
UNDER A BETTER-DEVELOPED MARINE LAYER. OUTSIDE OF SOME LINGERING
PATCHY CLOUDINESS THIS AFTERNOON, DON'T EXPECT TOO MUCH TO WRITE
HOME ABOUT WEATHER-WISE TODAY. PERHAPS SOME DRIZZLE AND PATCHY FOG
FOR COASTAL LOCATIONS AND HIGHER ELEVATION COASTAL RANGES, BUT
NOTHING WE AREN'T USED TO.
LONG TERM
(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 313 AM PDT THU APR 17 2025
DECENT WARM UP ON THE WAY FRIDAY THROUGH THE WEEKEND AS THE UPPER
LOW MOVES OUT AND A RIDGING PATTERN BUILDS IN ACROSS THE WEST COAST.
WITH THE LOW MOVING OUT, WE DO HAVE A WINDOW OF AN OFFSHORE-ORIENTED
PRESSURE GRADIENT AS SURFACE HIGH PRESSURE BUILDS INLAND IN THE PNW.
THIS WILL PROMOTE A SHORT PERIOD OF OFFSHORE WINDS BOTH FRIDAY AND
SATURDAY MORNINGS, BUT IT LOOKS TO BE MOSTLY UNIMPACTFUL. THE
SURFACE PRESSURE GRADIENT ISN'T PARTICULARLY STRONG, AND WE'RE
REALLY LACKING THE UPPER LEVEL SUPPORT NEEDED FOR A STRONG,
PROLONGED OFFSHORE WIND. THERE IS A RELATIVE MAX IN THE 850MB FLOW
ACROSS THE NORTH BAY FRIDAY MORNING, MIGRATING OVER COASTAL MARIN
AND SF BY THE EVENING HOURS. I WOULD EXPECT AT LEAST SOME BREEZY NE
WINDS IN THE INTERIOR NORTH BAY FRIDAY MORNING. HOWEVER, BY THE
EVENING HOURS, THE PRESSURE GRADIENT TURNS MORE ONSHORE DURING PEAK
SURFACE HEATING, AND THE LAYER REMAINS INTACT. WITH THIS NEAR
CANCELING OUT OF THE PRESSURE GRADIENT AND STRONG STABILITY ABOVE
THE MARINE LAYER (WHICH SITS BELOW THE 850MB HEIGHT), I REALLY DON'T
EXPECT ANY OFFSHORE WIND TO BE OF ANY IMPACT TO AREAS OUTSIDE OF THE
INTERIOR HIGHER TERRAIN. EVEN WITH THIS OFFSHORE WIND FOR INLAND
AREAS, MOISTURE RECOVERY WILL BE IN GOOD SHAPE, AND BEING SHORT-
LIVED, AFTERNOON MINIMUM RH DOESN'T SEEM TO BE AN ISSUE EITHER.
THIS ALL SEEMS LIKE IT WILL BE JUST MORE OF A NUISANCE, REALLY.
FOR THE REST OF THE FORECAST PERIOD, QUIET WEATHER IN STORE WITH
AFTERNOON HIGHS RIGHT AROUND SEASONAL AVERAGES.
AVIATION
(18Z TAFS)
ISSUED AT 1113 AM PDT THU APR 17 2025
MOSTLY MVFR THROUGHOUT THE REGION, BUT SOME TERMINALS MAY EXPERIENCE
A BRIEF MOMENT OF VFR CONDITIONS UNTIL THE EARLY AFTERNOON HOURS
(NEAR 20-21Z) WHERE VFR IS EXPECTED TO RETURN. CONDITIONS RETURN TO
MVFR TONIGHT WITH A CHANCE FOR A EARLIER RETURN NEAR 04-05Z.
MONTEREY BAY TERMINALS HAVE A HIGHER CHANCE TO REMAIN SOCKED IN
THROUGHOUT THE TAF PERIOD. VFR IS EXPECTED TO RETURN LATE FRIDAY
MORNING BUT THERE IS A FAIR CHANCE MVFR CONDITIONS PUSH BEYOND 18Z.
WINDS WILL BE MOSTLY MODERATE WITH LIGHT WINDS TONIGHT.
VICINITY OF SFO...MVFR CONDITIONS PREVAIL. VFR IS EXPECTED NEAR 23Z
BUT THERE IS CHANCE FOR CLEARING NEAR 21Z, AS CONFIDENCE IS MODERATE
ON TIMING. MVFR WILL REBUILD TONIGHT WITH A CHANCE FOR A EARLY
RETURN.
SFO BRIDGE APPROACH...SIMILAR TO SFO.
MONTEREY BAY TERMINALS...MVFR. THERE IS A GOOD CHANCE THAT MVFR WILL
STICK AROUND THROUGH THE TAF PERIOD, ESPECIALLY FOR KMRY AS STRATUS
CONTINUES TO FUNNEL OVER THE TERMINALS. IF CONDITIONS IMPROVE,
EXPECT NEAR 21Z FOR KSNS WITH A RETURN EARLY THIS EVENING.
MARINE
(TODAY THROUGH TUESDAY)
ISSUED AT 911 AM PDT THU APR 17 2025
MODERATE TO FRESH NORTHERLY BREEZE ACROSS THE OUTER COASTAL
WATERS WITH LIGHT AND VARIABLE WINDS CLOSER TO THE COAST. AS THE
WINDS DIMINISH, ROUGH SEAS WILL SUBSIDE THURSDAY NIGHT THROUGH
FRIDAY BEFORE ANOTHER STRONG BREEZE REBUILDS SEAS THIS WEEKEND
WHICH WILL LIKELY PERSIST INTO EARLY NEXT WEEK.
MTR WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 3 PM PDT THIS AFTERNOON FOR PT ARENA
TO PT REYES 10-60 NM.
SMALL CRAFT ADVISORY FROM 9 PM FRIDAY TO 3 AM PDT SATURDAY FOR
PT ARENA TO PT REYES 10-60 NM.
SHORT TERM...BEHRINGER
LONG TERM....BEHRINGER
AVIATION...SO
MARINE...SO
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