368
FXUS66 KMTR 171015
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
315 AM PDT THU APR 17 2025
..NEW SYNOPSIS, SHORT TERM, LONG TERM, MARINE
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
(06Z TAFS)
ISSUED AT 1033 PM PDT WED APR 16 2025
MVFR STRATUS EXTENDS ACROSS THE NORTH BAY, NORTHERN SAN FRANCISCO
BAY, WESTERN SAN MATEO PENINSULA, AND SOUTHERN MONTEREY COUNTY, AND
WILL BUILD ACROSS THE COASTAL REGIONS OVERNIGHT. LOW TO MODERATE
CONFIDENCE ON CLEARING TIMES THURSDAY MORNING, WITH SOME MODEL
GUIDANCE HOLDING ONTO THE CEILINGS WELL INTO THE AFTERNOON AND
EVENING. OPTED TO BRING THE CLEARING TIMES A LITTLE LATER, ALIGNING
WITH THE MODEL CONSENSUS. BREEZY NORTHWESTERLY WINDS WILL BUILD
THROUGH THURSDAY AFTERNOON. THURSDAY NIGHT INTO FRIDAY, LOW TO
MODERATE CONFIDENCE ON STRATUS EXTENT AND TIMING, WITH SOME MODELS
SHOWING STRATUS DEVELOPMENT AT SIGNIFICANTLY LATER TIMES THAN THOSE
REFLECTED IN THE TAFS.
VICINITY OF SFO... MVFR CEILINGS PERSIST OVERNIGHT AND THROUGH LATE
THURSDAY MORNING. MODERATE CONFIDENCE ON THE TIMING OF STRATUS
CLEARING WITH THE MODELS TRENDING TOWARDS CLEARING LATER THURSDAY
MORNING OR EVEN EARLY IN THE AFTERNOON. BREEZY WEST WINDS WILL
RESUME THURSDAY AFTERNOON. LOW CONFIDENCE IN THE ARRIVAL TIME OF
STRATUS AT THE TERMINAL ON THURSDAY EVENING, WITH SOME HIGH
RESOLUTION MODELS OPTING FOR STRATUS DEVELOPMENT RELATIVELY EARLY
IN THE EVENING WHILE OTHERS OPT TO DEVELOP THE STRATUS AFTER
MIDNIGHT.
SFO BRIDGE APPROACH... SIMILAR TO SFO.
MONTEREY BAY TERMINALS... VFR THROUGH THE NEXT COUPLE OF HOURS
BEFORE MVFR STRATUS RETURNS OVERNIGHT THROUGH THURSDAY MORNING.
CEILINGS MIGHT LIFT ABOVE MVFR CRITERIA BEFORE THE SKIES FULLY CLEAR
OUT EARLY THURSDAY AFTERNOON, AS BREEZY ONSHORE WINDS RETURN TO THE
REGION. MODERATE CONFIDENCE IN AN EARLY RETURN OF STRATUS LATE
THURSDAY AFTERNOON, WITH SOME MODELS CONTINUING TO HOLD OFF THE
STRATUS DECK THROUGH THE END OF THE TAF PERIOD.
MARINE
(TODAY THROUGH TUESDAY)
ISSUED AT 313 AM PDT THU APR 17 2025
THE GRADIENT BETWEEN HIGH PRESSURE IN THE EASTERN PACIFIC AND
LOWER PRESSURE OVER THE WESTERN US IS SUPPORTING A 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...DIALH
MARINE...FLYNN
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