883
FXUS66 KMTR 141127
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
427 AM PDT FRI MAR 14 2025
..NEW AVIATION, MARINE
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
(12Z TAFS)
ISSUED AT 427 AM PDT FRI MAR 14 2025
WIDESPREAD STRATIFORM RAIN ASSOCIATED WITH AN INCOMING WARM FRONT IS
SPREADING ACROSS THE BAY AREA AND CENTRAL COAST, CAUSING POTENTIAL
DECREASED CEILINGS AND VISIBILITIES, GENERALLY TO MVFR. SOUTHERLY
WIND SPEEDS ARE INCREASING WITH THE APPROACH OF THE WARM FRONT, AND
THE STRONG WINDS ARE EXPECTED TO TURN TO THE NORTHWEST AS THE
FRONT PASSES THROUGH LATER THIS MORNING. WILL NEED TO KEEP AN EYE
ON OBSERVATIONS, AS SOME OF THE HIGH RESOLUTION MODELS HAVE THE
FRONTAL PASSAGE COMING IN FASTER THAN WHAT THE TAFS CURRENTLY
REFLECT. WIND GUSTS OF 30-35 KNOTS ARE EXPECTED AT THE TERMINALS.
BEHIND THE FRONTAL PASSAGE, RAIN SHOWERS PERSIST INTO THE EVENING
HOURS AS THE GUSTY WINDS SLOWLY DIMINISH, WITH LIGHT WINDS
RETURNING OVERNIGHT. MID-LEVEL CLOUDS ARE EXPECTED TO PERSIST
THROUGH THE DAY, ALTHOUGH AFTER THE FRONT PASSES, CEILINGS ARE
EXPECTED TO REMAIN ABOVE MVFR CRITERIA.
VICINITY OF SFO... RAIN CONTINUES THROUGH THE MORNING WITH
INCREASING WIND SPEEDS FROM THE SOUTH. THE FRONTAL PASSAGE THAT WILL
SHIFT WINDS TO THE NORTHWEST IS EXPECTED AROUND 18-19Z, ALTHOUGH
WILL NEED TO KEEP AN EYE ON THE OBSERVATIONS AS SOME HIGH RESOLUTION
MODELS ARE TRYING TO SPEED UP THE FRONT. MODERATE CONFIDENCE IN WIND
GUSTS REACHING 35 KNOTS IN THE AFTERMATH OF THE FRONTAL PASSAGE,
BASED ON OUTPUT FROM HIGH RESOLUTION MODELS. RAIN SHOWERS WILL ALSO
PERSIST IN THE POST-FRONTAL ENVIRONMENT. THE GUSTY WINDS AND RAIN
SHOWERS WILL BOTH DIMINISH THROUGH THE EVENING HOURS, AND
EFFECTIVELY CEASE OVERNIGHT.
SFO BRIDGE APPROACH... SIMILAR TO SFO.
MONTEREY BAY TERMINALS... RAIN THROUGH THE MORNING WITH BREEZY AND
GUSTY SOUTHERLY WINDS. WINDS SHIFT TO THE NORTHWEST AFTER THE
FRONTAL PASSAGE, REMAINING GUSTY THROUGH THE EVENING. RAIN SHOWERS
WILL PERSIST AFTER THE FRONTAL PASSAGE INTO THE EVENING HOURS.
MARINE
(TODAY THROUGH WEDNESDAY)
ISSUED AT 427 AM PDT FRI MAR 14 2025
GALE FORCE GUSTS AND ROUGH SEAS WILL MOVE THROUGH THE WATERS AND
CREATE HAZARDOUS CONDITIONS THROUGH THE DAY. 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 UNTIL 9 AM PDT THIS MORNING FOR CAZ509-512.
WIND ADVISORY UNTIL 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 MRY BAY-SF
BAY N OF BAY BRIDGE.
GALE WARNING UNTIL 3 PM PDT THIS AFTERNOON FOR PIGEON PT TO PT
PINOS 0-10 NM-PT ARENA TO PT REYES 0-10 NM-PT ARENA TO PT
REYES 10-60 NM-PT REYES TO PIGEON PT 0-10 NM.
GALE WARNING UNTIL 9 PM PDT THIS EVENING FOR PIGEON PT TO PT
PINOS 10-60 NM-PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM.
SHORT TERM...FLYNN
LONG TERM....FLYNN
AVIATION...DIALH
MARINE...DIALH
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