947
FXUS66 KMTR 120955
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
255 AM PDT TUE AUG 12 2025
..NEW MARINE, BEACHES
KEY MESSAGES
UPDATED AT 333 AM PDT MON AUG 11 2025
- MODERATE HEATRISK CONTINUES THROUGH MONDAY FOR PORTIONS OF NORTH,
EAST, AND SOUTH BAY COUNTIES AND INTERIOR MONTEREY AND SAN
BENITO COUNTIES.
- ELEVATED FIRE WEATHER CONCERNS PERSIST THROUGH MONDAY GIVEN THE WARM
AND DRY CONDITIONS COMBINED WITH BREEZY AFTERNOON AND EVENING
WINDS.
- PATTERN CHANGE TUESDAY, WITH COOLER WEATHER AND COASTAL DRIZZLE
RETURNING TO THE FORECAST.
UPDATE
ISSUED AT 850 PM PDT MON AUG 11 2025
TEMPERATURES ACROSS THE BAY AREA WERE GENERALLY COOLER BY ABOUT 5 TO
6 DEGREES FOR THE LOWER ELEVATIONS AMD UP TO 10 DEGREES COOLER
ACROSS PORTIONS OF THE ELEVATED TERRAIN. THIS DOES NOT HOLD TRUE FOR
THE CENTRAL COAST WHERE INTERIOR LOCATIONS SAW TEMPERATURES RISE BY
1-3 DEGREES. THE GENERAL COOLING TREND CONTINUES EVERYWHERE AS HIGH
PRESSURE STARTS TO BREAK DOWN AND ANOTHER UPPER LEVEL TROUGH PUSHES
IN FROM THE NORTH. THE EXCEPTION WILL AGAIN BE FOR THE INTERIOR
CENTRAL COAST WHERE TEMPERATURES WILL NOT START TO SIGNIFICANTLY
COOL DOWN UNTIL WEDNESDAY. AS TROUGHING RETURNS, THE MARINE LAYER IS
EXPECTED TO DEEPEN AND COASTAL DRIZZLE/FOG IS LIKELY ALONG THE
COASTLINE.
SHORT TERM
ISSUED AT 152 PM PDT MON AUG 11 2025
(THIS EVENING THROUGH TUESDAY)
WELCOME TO THE LAND OF MICRO-CLIMATES. WE'VE BEEN LOCKED IN THIS
PATTERN FOR A FEW DAYS NOW, BUT IT IS STILL IMPRESSIVE
NONETHELESS. COASTAL STRATUS/NATURAL AC IS KEEPING THE COAST
COOL, BUT GO INLAND AND TEMPS SKY ROCKET. 100-105 BEING REPORTED
OVER SOUTHERN MONTEREY THIS AFTERNOON. THE TEMP SPREAD IS ALSO IN
THE VERTICAL WITH COASTAL SITES SHOWING TEMPS IN THE UPPER 50S,
BUT JUST A 1K FEET UP THE MOUNTAINSIDE TEMPS ARE IN THE 80S.
TONIGHT AND TUESDAY: THE RIDGE THAT BROUGHT INTERIOR HEAT IS
FINALLY EASING TONIGHT AND TUESDAY. AN UPSTREAM TROUGH WILL BEGIN
TO NOSE ITS WAY INTO CA. AS MENTIONED, BEFORE TUESDAY WILL BE MORE
OF A TRANSITION DAY WITH SENSIBLE WEATHER AS TEMPS BEGIN TO EASE.
NIGHT/MORNING CLOUDS WITH COASTAL FOG/DRIZZLE PERSIST. WHILE
TEMPS EASE GENERALLY SPEAKING, STILL EXPECTING TO SEE INTERIOR
REACH THE 90S TO JUST OVER 100.
FOR THOSE WANTING TO SEE THE METEOR SHOWER. BAD NEWS, IT LOOKS
LIKE CLOUDS WILL LIKELY WIN OUT WITH A SOLID STRATUS DECK. IF
YOU'RE IN THE HILLS YOU WILL HAVE A BETTER CHANCE.
LONG TERM
ISSUED AT 230 PM PDT MON AUG 11 2025
(TUESDAY NIGHT THROUGH NEXT SUNDAY)
THE BEGINNING OF THE LONG TERM GETS LITTLE EXCITING THANKS TO
POST-TROPICAL CYCLONE IVO. AS IVO CONTINUES TO WEAKEN ITS MOISTURE
REMAINS. MOISTURE TRANSPORT DOES GET WRAPPED ON THE WESTERN
PERIPHERY OF THE SW RIDGE AND ON THE EASTERN SIDE OF A LOW OVER
THE EPAC, BUT DOES IT MAKE IT TO CA IN A MEANINGFUL WAY? LATEST
NWP MODELS BRING THE MOISTURE TOWARD CA, BUT IT GETS
HALTED/DEFLECTED BY THE APPROACHING UPSTREAM TROUGH. WHERE THIS
COULD BE A LITTLE PROBLEMATIC IS IF THE TROUGH IS SLOW OR FARTHER
NORTH THE MOISTURE COULD MAKE IT MORE NORTH. FOR NOW IT LOOKS TO
REMAIN OFF THE CENTRAL CA COAST. WHERE THE MOISTURE DOES TRAVEL IT
WILL ENCOUNTER SOME INSTABILITY WITH MUCAPE EXCEEDING 100 J/KG
AND LAPSE RATES GREATER THAN 7C/KM. SOME OF THE HOTTER CAMS DO
GENERATE A FEW SHOWERS OVER MONTEREY COUNTY WEDNESDAY, BUT THAT
IS PUSHING IT. IT'S A NON- EVENT FOR NOW, BUT WE'LL BE WATCHING.
OF MUCH HIGHER CONFIDENCE WILL BE WIDESPREAD COOLING WITH MORE
COASTAL CLOUDS AND DRIZZLE. THE COOL DOWN WILL PERSIST INTO NEXT
WEEKEND WITH SEASONABLY COOL TEMPERATURES.
AVIATION
(06Z TAFS)
ISSUED AT 920 PM PDT MON AUG 11 2025
LOW STRATUS HAS BEGUN MAKING PROGRESS INLAND THIS EVENING WITH
MVFR CEILINGS IN PLACE FOR TERMINALS CLOSEST TO THE SHORELINE,
WITH THE NORTH BAY TERMINALS EXPECTED TO FOLLOW SUIT BEFORE
MIDNIGHT. MARINE LAYER AS MEASURED NEAR MONTEREY BAY HAS BEEN
STEADY AT AROUND 1500FT WITH STEADY ONSHORE FLOW PERSISTING
THROUGH THE TAF PERIOD.
VICINITY OF SFO...MVFR CEILINGS FILLED IN SOONER THAN EXPECTED AT
KSFO WITH RECENT SATELLITE TRENDS SUGGESTING CEILINGS WILL HOLD
IN PLACE THROUGH THE OVERNIGHT INTO TUESDAY MORNING. ASIDE FROM
THE EARLY ARRIVAL TIME AT KSFO, EXPECT LOW STRATUS TO BEGIN
CLEARING OUT BY MID-MORNING FOR BAY AREA TERMINALS.
SFO BRIDGE APPROACH...SIMILAR TO SFO.
MONTEREY BAY TERMINALS...MVFR/IFR CEILINGS WILL PERSIST THROUGH
TONIGHT INTO TUESDAY MORNING. KSNS IS EXPECTED TO CLEAR OUT BY
LATE MORNING TUESDAY, AND A CHANCE THAT KMRY HOLDS ONTO MVFR
CEILINGS INTO EARLY AFTERNOON, AND SIMILAR RETURN TIMES TUESDAY
EVENING LATE IN THE TAF PERIOD.
MARINE
(TODAY THROUGH SUNDAY)
ISSUED AT 248 AM PDT TUE AUG 12 2025
A GENTLE TO MODERATE NORTHWESTERLY BREEZE WILL PREVAIL TODAY,
INCREASING TO BECOME FRESH TO STRONG WEDNESDAY WITH WIDESPREAD
STRONG GUSTS BY THURSDAY. MODERATE SEAS WILL BUILD TO BECOME
ROUGH FOR INNER WATERS AND OUTER WATERS BY THURSDAY.
BEACHES
ISSUED AT 248 AM PDT TUE AUG 12 2025
A LONG PERIOD (17 SECONDS) SOUTHWESTERLY SWELL WILL RESULT IN AN
INCREASED RISK FOR SNEAKER WAVES AND RIP CURRENTS THROUGH THIS
EVENING. GREATEST RISK WILL BE ALONG SOUTHWEST FACING BEACHES,
INCLUDING BUT NOT LIMITED TO STINSON BEACH, SANTA CRUZ BOARDWALK
BEACH, AND TWIN LAKES BEACH. SNEAKER WAVES CAN UNEXPECTEDLY RUN
SIGNIFICANTLY FARTHER UP THE BEACH THAN NORMAL, INCLUDING OVER
ROCKS AND JETTIES. REMAIN OUT OF THE WATER TO AVOID HAZARDOUS
SWIMMING CONDITIONS AND NEVER TURN YOUR BACK ON THE OCEAN!
SARMENT
MTR WATCHES/WARNINGS/ADVISORIES
CA...BEACH HAZARDS STATEMENT THROUGH THIS EVENING FOR CAZ505-529.
PZ...SMALL CRAFT ADVISORY FROM 1 PM THIS AFTERNOON TO 9 PM PDT THIS
EVENING FOR SF BAY N OF BAY BRIDGE.
SMALL CRAFT ADVISORY UNTIL 3 AM PDT WEDNESDAY FOR PT PINOS TO PT
PIEDRAS BLANCAS 0-10 NM.
SHORT TERM...MM
LONG TERM....MM
AVIATION...JM
MARINE...SARMENT
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