698
FXUS66 KMTR 161808
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
1108 AM PDT SAT AUG 16 2025
..NEW AVIATION
KEY MESSAGES
UPDATED AT 236 AM PDT SAT AUG 16 2025
- CLOUDY WITH DRIZZLE AND VERY LIGHT RAIN ALONG THE COAST THIS
MORNING NEAR AND SOUTH OF THE GOLDEN GATE BRIDGE
- WINDS EASE THIS EVENING
- COOL FOR SUNDAY, BUT WARMING FOR THE NEXT WORK WEEK
UPDATE
ISSUED AT 922 AM PDT SAT AUG 16 2025
THE SHORT TERM FORECAST WAS UPDATED THIS MORNING TO CONCENTRATE
THE COVERAGE OF DRIZZLE/VERY LIGHT RAIN NEAR AND SOUTH OF THE
GOLDEN GATE BRIDGE THIS MORNING. NOTICEABLE ONSHORE FLOW, AS
EVIDENCED BY WIND GUSTS IN EXCESS OF 25 KNOTS AT KSFO, CONTINUES
AND WILL PERSIST THROUGH THE DAY TODAY. WITH THE DEPTH OF THE
MOIST LAYER BETWEEN 1500-2000 FT PER ACARS DATA FROM KOAK IN
TANDEM WITH CONVERGENCE ASSOCIATED WITH FRICTIONAL DIFFERENCES
BETWEEN THE OCEAN AND LAND, WIDESPREAD DRIZZLE HAS RESULTED. IN
FACT, DOWNTOWN SAN FRANCISCO AND HALF MOON BAY HAVE REPORTED
MEASURABLE RAINFALL, WITH KHAF JUST UNDER 0.10" OF ACCUMULATION OF
A MODERATE TO HEAVY DRIZZLE AND/OR VERY LIGHT RAIN. I ANTICIPATE
THAT COASTAL DRIZZLE WILL CONTINUE ALONG THE AFOREMENTIONED
CORRIDOR THROUGH AT LEAST EARLY AFTERNOON.
SHORT TERM
ISSUED AT 236 AM PDT SAT AUG 16 2025
(TODAY AND TONIGHT)
TONIGHT'S FORECAST WAS BROUGHT TO YOU IN PART BY CAFFEINE. WINDS
ACROSS THE REGION HAVE PEAKED AND HAVE BEGUN TO REDUCE, BUT WILL
STAY BREEZY IN THE INTERIOR EAST BAY FOR SATURDAY. CLOUD COVER
CONTINUES TO BUILD WITH DRIZZLE AND LIGHT RAIN AFFECTING THE
COAST. A FAIR BIT OF POLISHING WAS DONE TO THE DRIZZLE/LIGHT RAIN
CHANCES INTO THE MORNING AND LINGERING INTO SATURDAY AFTERNOON.
THESE PRECIP CHANCES COME FROM SOME WARM SECTOR MOISTURE AHEAD OF A
COLD FRONT. SAID COLD FRONT WAS ASSOCIATED WITH AN ATMOSPHERIC RIVER
THAT AFFECTED THE PACIFIC NORTHWEST EARLIER TODAY, BUT HAS SINCE
LOST MUCH OF ITS STRENGTH. SO FOR US, IT'LL CAUSE CLOUDY AND DRIZZLY
CONDITIONS WITH SOME MOMENTS OF LIGHT RAIN POSSIBLE THIS MORNING.
CLOUD COVER WILL STRUGGLE TO ERODE, WITH ONLY THE INTERIOR AREAS AND
HIGHER ELEVATIONS SEEING CLEARING SKIES. SHORT TERM MODELS ALSO HINT
AT COASTAL AREAS KEEPING DRIZZLE CHANCES THROUGH THE DAY WITH
PATCHES OF FOG; A VERY FOGUST-LIKE DAY FOR THE 16TH OF AUGUST.
MORE ORGANIZED RAIN CHANCES LOOK TO STAY TO THE NORTH, BUT THERE
IS A SLIGHT CHANCE FOR SOME SHOWERS TO MOVE INTO THE NORTHERNMOST
PORTIONS OF NAPA AND SONOMA COUNTIES INTO THE EVENING ALONG THE
FRONT ITSELF. HOWEVER IF THESE SHOWERS BREAK INTO THE NORTH BAY
COUNTIES, THEY DON'T LOOK PARTICULARLY IMPACTFUL.
SLIGHTLY DRIER AIR ARRIVES BEHIND THE FRONT TONIGHT, LEADING TO LESS
DRIZZLE CHANCES, AND NOT AS WIDESPREAD CLOUD COVER (BUT STILL FAIRLY
CLOUDY FOR THE COAST, BAYS AND IMMEDIATE VALLEYS).
LONG TERM
ISSUED AT 236 AM PDT SAT AUG 16 2025
(SUNDAY THROUGH FRIDAY)
SUNDAY SEES CONTINUED COOLING IN THE POST-FRONTAL ENVIRONMENT,
MAKING IT THE COOLEST DAY OF THE FORECAST FOR MOST OF THE CWA. THE
PATTERN THEN BEGINS CHANGING TO A RIDGE SET UP INTO THE WORK WEEK,
LEADING TO SOME SLIGHT WARMING AND LESS CLOUD COVER FOR MONDAY. THE
WARMING TREND LOOKS TO CONTINUE THROUGH THE WORK WEEK AS THE RIDGE
BUILDS AND THE MARINE LAYER COMPRESSES AND RETREATS. AS OF THE MOST
RECENT FORECAST UPDATE, THURSDAY AND INTO THE WEEKEND LOOK TO SEE
THE FAR INTERIOR BREAK INTO THE 100S. CONFIDENCE IN THIS WARMING
TREND IS INCREASING AMONGST THE LONGER TERM MODELS, BUT THE TIMING
OF WHEN THE HEAT BREAKS AND THE NEXT COOLING TREND IS STILL HARD TO
NARROW DOWN. THERE ARE SOME HINTS THAT THIS RIDGE WON'T BE QUICK TO
PUSH EAST, MEANING THE HEATING COULD LAST THROUGH THAT WEEKEND AND
INTO THE NEXT WEEK. THIS WILL BE SOMETHING WORTH CHECKING BACK IN ON
AS THE FORECAST CONTINUES TO UPDATE.
AVIATION
(18Z TAFS)
ISSUED AT 1104 AM PDT SAT AUG 16 2025
GENERALLY IFR/MVFR CONDITIONS ACROSS MUCH OF THE REGION THIS MORNING
WITH THE NORTH BAY TERMINALS AT VFR. HOWEVER, LIFR CONDITIONS
PREVAIL AT HAF WITH HIGH CONFIDENCE TO REMAIN LIFR/IFR THROUGHOUT
THE TAF PERIOD. MODERATE CONFIDENCE FOR BAY AREA TERMINALS TO SEE
CEILINGS LIFT THIS AFTERNOON, BUT GENERALLY REMAIN MVFR AT OAK WITH
SFO SEEING CONDITIONS RETURNING TO VFR THIS EVENING. THE MONTEREY
BAY TERMINALS ARE MVFR AND WITH MODERATE TO HIGH CONFIDENCE FOR
IFR/MVFR CONDITIONS TO RETURN THIS EVENING. A WEST TO NORTHWEST
BREEZE WILL CONTINUE THIS AFTERNOON, YET SLIGHTLY WEAKER THAN
YESTERDAY. MODERATE CONFIDENCE FOR IFR/MVFR CONDITIONS TO RETURN TO
MOST TAF SITES THIS EVENING AND POTENTIALLY LOWERING TO LIFR EARLY
SUNDAY MORNING AROUND THE MONTEREY BAY TERMINALS.
VICINITY OF SFO...IFR/MVFR. MODERATE (50% PROBABILITY) CONFIDENCE FOR
CEILINGS TO LIFT WITH SFO BECOMING VFR THIS EVENING BEFORE LOWERING
TO IFR/MVFR ONCE AGAIN TONIGHT. HIGH CONFIDENCE FOR WEST TO
NORTHWEST WINDS TO INCREASE THIS AFTERNOON WITH AT OR ABOVE 30KT.
WINDS WILL THEN EASE INTO EARLY SUNDAY MORNING.
SFO BRIDGE APPROACH...40% PROBABILITY THAT LOW STRATUS CLOUDS LINGER
ACROSS THE SAN MATEO BRIDGE APPROACH THROUGH THE TAF PERIOD. THEN
EARLIER CLEARING BY MID-MORNING ON SUNDAY.
MONTEREY BAY TERMINALS...MVFR. MODERATE TO HIGH CONFIDENCE FOR MVFR
CEILINGS TO REMAIN THROUGH MUCH OF THE TAF PERIOD. THEN MODERATE
CONFIDENCE FOR IFR/MVFR TO RETURN THIS EVENING AND POTENTIALLY
LOWERING TO LIFR EARLY SUNDAY MORNING. WESTERLY TO NORTHWESTERLY
WINDS WILL PREVAIL THROUGH THE TAF PERIOD.
MARINE
(TODAY THROUGH THURSDAY)
ISSUED AT 922 AM PDT SAT AUG 16 2025
THE OVERALL SEA STATE WILL BE DOMINATED BY MODERATE TO FRESH
NORTHWEST BREEZES, WITH NORTHWESTERLY SEAS OF 4 TO 6 FEET. PERIODS
ARE ANTICIPATED TO HOVER AROUND 5 TO 7 SECONDS THROUGH TONIGHT.
HAZARDOUS BOATING CONDITIONS, DUE TO STEEP TO VERY STEEP WAVES ARE
LIKELY TO ENSUE, LARGELY FOR SMALLER VESSELS AND CRAFTS ACROSS
AREA WATERS, INCLUDING THE BAYS. AFTER TONIGHT, PERIODS ARE
ANTICIPATED TO INCREASE CLOSER TO 10 SECONDS WHICH SHOULD HELP
DECREASE THE OVERALL STEEPNESS OF WAVES, THOUGH BOATING CONDITIONS
MAY STILL REMAIN HAZARDOUS. OTHERWISE, SECONDARY SOUTHERLY SWELL
WILL PERSIST, COURTESY OF RECENT TROPICAL ACTIVITY IN THE EASTERN
PACIFIC. SOUTHERLY SWELL PERIODS ARE ANTICIPATED TO AVERAGE
BETWEEN 12 AND 16 SECONDS WITH WAVE HEIGHTS AROUND 2 FEET OR LESS.
MTR WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 9 PM PDT THIS EVENING FOR SF BAY N OF
BAY BRIDGE.
SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO 9 PM PDT THIS
EVENING FOR MRY BAY.
SMALL CRAFT ADVISORY UNTIL 9 AM PDT SUNDAY FOR PT ARENA TO PT
REYES 0-10 NM-PT ARENA TO PT REYES 10-60 NM-PT PINOS TO PT
PIEDRAS BLANCAS 0-10 NM.
SMALL CRAFT ADVISORY UNTIL 3 AM PDT SUNDAY FOR PT REYES TO
PIGEON PT 0-10 NM.
UPDATE...BAIN
SHORT TERM...MURDOCK
LONG TERM....MURDOCK
AVIATION...RGASS
MARINE...BAIN
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