694
FXUS66 KMTR 140838
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
138 AM PDT FRI MAR 14 2025
..NEW SYNOPSIS, SHORT TERM, LONG TERM
SYNOPSIS
ISSUED AT 1250 AM PDT FRI MAR 14 2025
RAIN AND GUSTY WINDS THIS MORNING WILL TAPER OFF BY THE
AFTERNOON. THE NEXT ROUND OF RAIN ARRIVES SUNDAY, WITH ONLY MINOR
IMPACTS EXPECTED.
SHORT TERM
(TODAY AND TONIGHT)
ISSUED AT 1250 AM PDT FRI MAR 14 2025
A PREFRONTAL RAIN BAND WILL PUSH THROUGH FROM ROUGHLY 3 AM TO 10
AM. THE TRIPLE POINT BETWEEN A WARM, COLD, AND OCCLUDED FRONT WILL
MOVE THROUGH THE BAY AREA AROUND MID-DAY, WHICH COULD TRIGGER A
FEW STRONG SHOWERS. THERE IS A 10-20% CHANCE FOR THUNDERSTORMS,
BUT THE THREAT ONLY LASTS FOR A BRIEF WINDOW AROUND NOON AS THE
MOISTURE BAND IS NARROW AND FAST MOVING WITH THIS SYSTEM. THE
WINDS ARE COMING IN STRONGER THAN PREVIOUSLY EXPECTED. THE PT.
ARENA BUOYS IS ALREADY GUSTING ABOVE 30 KTS, WHICH IS 10 KTS STRONGER
THAN ANY GUIDANCE SUGGESTED AT THIS TIME. I USED A 50/50 BLEND OF
THE 00Z LOCAL WRF AND 06Z HRRR FOR WIND AND GUSTS, WHICH PUT THE
COASTAL PENINSULA, SANTA CRUZ MOUNTAINS, AND INTERIOR EAST BAY
INTO WIND ADVISORY CRITERIA. IF THIS BLEND IS CORRECT, SOUTHERLY
WINDS IN THESE AREAS WILL GUST TO AROUND 45 MPH IN THE MID TO
LATE MORNING BEFORE SHIFTING TO WESTERLY AND DIMINISHING BACK TO
20-30 MPH GUSTS BEHIND THE FRONT. THE AFTERNOON WILL BE CHILLY
AND BREEZY, BUT THE RAIN WILL STOP AND SKIES BEGIN TO CLEAR
BEFORE THE SUN GOES DOWN TONIGHT.
LONG TERM
(SATURDAY THROUGH THURSDAY)
ISSUED AT 1250 AM PDT FRI MAR 14 2025
SATURDAY LOOKS LIKE THE BEST DAY FOR ANY OUTDOOR ACTIVITIES AS A
RIDGE BUILDS IN. NO RAIN, MUCH LIGHTER WIND, AND MORE SUNSHINE ARE
IN STORE. THE AIR MASS WILL STILL BE COLD, BUT IT WILL FEEL MUCH
WARMER WITH THE MORE PLEASANT CONDITIONS. THIS BREAK WON'T LAST
VERY LONG, HOWEVER, AS ANOTHER SYSTEM MOVES IN ON SUNDAY.
FORTUNATELY THE TIMING ON THIS KEEPS SHIFTING LATER, SO MOST
PEOPLE WILL BE ABLE TO ENJOY A DRY MORNING BEFORE THE RAIN CHANCES
START RAMPING UP IN THE AFTERNOON/EVENING. IF THE TIMING TREND
HOLDS, MOST OF THE RAIN WILL ACTUALLY FALL OVERNIGHT. THE CENTER
FOR WESTERN WEATHER AND WATER EXTREMES (CW3E) WRF ENSEMBLE MEAN IS
SHOWING IVT PEAKING AT ROUGHLY 325 KG/MS AND STAYING ABOVE 250
FOR AROUND 18 HOURS. THAT'S NOT QUITE INTENSE OR LONG ENOUGH TO
QUALIFY AS EVEN A WEAK ATMOSPHERIC RIVER, WHICH MEANS THIS EVENT
SHOULD BE MOSTLY BENEFICIAL, WITH NO SIGNIFICANT FLOODING THREAT.
OVERALL WE ARE EXPECTING AROUND 0.25"- 1", WITH A LITTLE MORE
POSSIBLE IN THE NORTH BAY MOUNTAINS. THE RAIN WILL START AS STEADY
STRATIFORM PRECIPITATION BEFORE THE COLD FRONT MOVES THROUGH
EARLY MONDAY AND THE MODE SWITCHES TO CONVECTION THROUGH MONDAY
AFTERNOON. WITH THE 1000-500 MB THICKNESS DROPPING BELOW 534 DM,
THESE CLOUDS WILL BE MOSTLY ABOVE THE FREEZING LEVEL, INCREASING
THE CHANCE FOR HIGH ELEVATION SNOW, HAIL, AND THUNDERSTORMS.
OF COURSE THE LIMITING FACTOR IS DRIER AIR MOVING IN
SIMULTANEOUSLY, WHICH WILL WORK TO INHIBIT ALL OF THE PHENOMENA
LISTED IN THE PREVIOUS SENTENCE. THIS DRIER AIR WILL CAUSE THE
CLOUDS TO CLEAR OUT. THE CLEAR SKIES, COMBINED WITH THE COLD AIR
MASS WILL LEAD TO A CHILLY START TUESDAY. HIGH PRESSURE WILL
CONTINUE TO BUILD IN THROUGH THE MIDDLE OF THE WEEK. IN THE
EXTENDED RANGE, THERE IS A CHANCE FOR VERY LIGHT RAIN ON THURSDAY,
BUT OVERALL THE PATTERN WILL FLATTEN OUT A BIT, WITH A TREND
TOWARDS WARMER AND DRIER CONDITIONS AS THE MONTH CONTINUES.
AVIATION
(06Z TAFS)
ISSUED AT 1025 PM PDT THU MAR 13 2025
GUSTY WINDS AND RAIN ARE EXPECTED TO RETURN OVERNIGHT WITH MOST
STATIONS SEEING MVFR CONDITIONS THROUGH THE OVERNIGHT HOURS INTO
TOMORROW AFTERNOON. CIGS WILL BUILD IN 09Z-12Z AS THE NEXT ROUND OF
RAIN ARRIVES WITH SHOWERS STARTING FIRST OVER THE NORTH BAY AND THEN
MOVING NORTH TO SOUTH. GUSTY SOUTHERLY WINDS WILL START TO BUILD IN
AFTER 09Z WITH GUSTS BETWEEN 30 TO 35 KNOTS POSSIBLE AT MOST SITES.
AFTER COLD FRONTAL PASSAGE (APPROXIMATELY BETWEEN 18Z-22Z) WINDS
WILL SHIFT TO A MORE NORTHWESTERLY DIRECTION WITH GUSTY CONDITIONS
TO CONTINUE THROUGH THE AFTERNOON HOURS. WINDS WILL GRADUALLY EASE
AND SHOWER CHANCES DECREASE BY THE LATE AFTERNOON/EARLY EVENING
HOURS. PERIODS OF DECREASED VISIBILITY ARE POSSIBLE AS SHOWERS MOVE
THROUGH THE REGION WITH TEMPORARY DECREASES BELOW WHAT IS IN THE TAF
POSSIBLE IF HEAVIER RAIN MOVES DIRECTLY OVER THE TAF SITE.
VICINITY OF SFO...VFR BECOMING MVFR OVERNIGHT. SHOWERS REACH SFO BY
EARLY FRIDAY MORNING WITH WIDESPREAD RAIN EXPECTED TO CONTINUE INTO
EARLY FRIDAY AFTERNOON. SHOWERS WILL BECOME MORE SCATTERED FRIDAY
AFTERNOON INTO THE EVENING WITH DRY CONDITIONS RETURNING BY LATE
FRIDAY EVENING. WINDS WILL BE GUSTY WITH GUSTS UP TO 33 KNOTS
POSSIBLE. GFSLAMP GUIDANCE INDICATES SOME POTENTIAL FOR GUSTS UP TO
37 KNOTS FRIDAY AFTERNOON AS THE COLD FRONT PASSES. PROBABILISTIC
GUIDANCE SHOWS LOW CONFIDENCE IN THIS SCENARIO BUT CONFIDENCE IS
FAIRLY HIGH THAT GUSTS OF 30+ KNOTS ARE LIKELY.
SFO BRIDGE APPROACH...SIMILAR TO SFO.
MONTEREY BAY TERMINALS...VFR BECOMING MVFR OVERNIGHT. LIGHT
SOUTHERLY WINDS STRENGTHEN OVERNIGHT, WITH GUSTS UP TO 30 TO 35
KNOTS POSSIBLE, BEFORE SHIFTING TO BE MORE NORTHWESTERLY AFTER COLD
FRONTAL PASSAGE BETWEEN 18Z-21Z. WINDS WILL REMAIN STRONG AND GUSTY
THROUGH FRIDAY EVENING BEFORE EASING FRIDAY NIGHT. WIDESPREAD RAIN
WILL REACH THE CENTRAL COAST AROUND 09Z TO 10Z WITH MVFR CIGS AND
DECREASES IN VISIBILITY POSSIBLE. CIGS WILL START TO IMPROVE BY LATE
FRIDAY AFTERNOON AS SHOWERS START TO BECOME MORE SCATTERED IN NATURE
AND LESS WIDESPREAD.
MARINE
(TONIGHT THROUGH NEXT WEDNESDAY)
ISSUED AT 935 PM PDT THU MAR 13 2025
HAZARDOUS CONDITIONS FOR SMALL CRAFTS CONTINUE ACROSS THE COASTAL
WATERS WITH STRONG WINDS AND ROUGH SEAS RETURNING TONIGHT INTO
TOMORROW AS THE NEXT SYSTEM MOVES IN. ROUGH, HAZARDOUS, CONDITIONS
PERSIST THROUGH MUCH OF NEXT WEEK AS A SERIES OF LOW PRESSURE
SYSTEMS APPROACH THE AREA, BRINGING WITH IT MULTIPLE ROUNDS OF
ELEVATED SURF AND FRESH TO STRONG WINDS.
MTR WATCHES/WARNINGS/ADVISORIES
CA...WIND ADVISORY FROM 4 AM TO 9 AM PDT THIS MORNING FOR CAZ509-512.
WIND ADVISORY FROM 5 AM TO 11 AM PDT THIS MORNING FOR CAZ510-515.
FROST ADVISORY UNTIL 9 AM PDT THIS MORNING FOR CAZ516>518.
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 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-PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM.
SMALL CRAFT ADVISORY UNTIL 3 AM PDT SATURDAY FOR PIGEON PT TO PT
PINOS 0-10 NM-PT REYES TO PIGEON PT 0-10 NM.
SHORT TERM...FLYNN
LONG TERM....FLYNN
AVIATION...KENNEDY
MARINE...KENNEDY
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