097
FXUS66 KMTR 180454
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
854 PM PST SUN NOV 17 2024
..NEW SYNOPSIS, UPDATE
SYNOPSIS
ISSUED AT 842 PM PST SUN NOV 17 2024
COLD TEMPERATURES WILL PERSIST BOTH TONIGHT INTO EARLY TOMORROW
MORNING, AND ONCE AGAIN MONDAY NIGHT INTO TUESDAY MORNING. BY
MIDWEEK, WE'LL SEE IMPACTFUL RAINFALL ACROSS THE NORTH BAY
TOWARDS THE MIDDLE OF THE WEEK, SPREADING SOUTHWARD LATE WEEK INTO
THE WEEKEND.
UPDATE
ISSUED AT 842 PM PST SUN NOV 17 2024
THE FORECAST REMAINS ON TRACK TONIGHT. SCATTERED LIGHT SHOWERS
ARE MOVING ACROSS PORTIONS OF THE BAY AREA AND NORTH BAY WITH ONLY
A TRACE TO A FEW HUNDRETHS OF PRECIPITATION BEING REPORTED.
OVERNIGHT LOWS INTO EARLY MONDAY MORNING WILL BE COLD ONCE AGAIN,
SIMILAR TO WHAT WE ALL WOKE UP TO THIS MORNING. ONCE WE PUT THE
COLD TEMPERATURES AND COASTAL FLOODING ASSOCIATED WITH THE KING
TIDE BEHIND US ON TUESDAY, WE'LL SEE RAIN CHANCES BEGIN TO RAMP
UP ACROSS THE NORTH BAY TUESDAY AFTERNOON AND EVENING AS THE
BEGINNING OF OUR FIRST ATMOSPHERIC RIVER EVENT OF THE SEASON
STARTS TO TAKE SHAPE. STILL A LOT OF DETAILS TO WORKOUT, BUT WE
CAN SAY WITH CONFIDENCE THAT THE NORTH BAY AREA WILL SEE THE MOST
IMPACTS OVER THE SECOND HALF OF THE WEEK INTO THE WEEKEND AS THE
AR SLOWLY SHIFTS SOUTH FROM NORCAL LATE IN THE WEEK.
SHORT TERM
(THIS EVENING THROUGH MONDAY)
ISSUED AT 120 PM PST SUN NOV 17 2024
CLOUDS ARE BUILDING IN ACROSS THE BAY AREA AND BEGINNING TO ENTER
THE CENTRAL COAST, IN ADVANCE OF A COLD FRONT THAT WILL BRING A
QUICK SHOT OF RAIN TO OUR REGION LATER THIS AFTERNOON INTO THE EARLY
HOURS OF MONDAY MORNING. THE FAST MOVING NATURE OF THE FRONT AND THE
STABILIZING ATMOSPHERE BEHIND THE FRONTAL PASSAGE WILL CONTRIBUTE TO
RELATIVELY LIGHT RAINFALL TOTALS FROM THE FRONT, WITH RAINFALL
TOTALS GENERALLY UP TO A TENTH OF AN INCH, POSSIBLY UP TO A QUARTER
OF AN INCH IN THE COASTAL RANGES OF THE NORTH BAY. HIGH TEMPERATURES
FOR TODAY AND TOMORROW ARE EXPECTED TO REMAIN AROUND THE SAME AS
YESTERDAY'S WITH THE LOWER ELEVATIONS HOVERING FROM THE MID 50S TO
THE MID 60S. LOWS TONIGHT WILL CONTINUE TO BE CHILLY, WITH THE
INLAND VALLEYS SEEING LOWS RANGE FROM THE MID 30S TO THE LOWER 40S
AND THE COASTAL AND BAYSHORE REGIONS SEEING LOWS FROM THE MID TO
UPPER 40S. THE OPERATIONS TEAM DISCUSSED A POSSIBLE FROST ADVISORY
DUE TO LOWS IN THE MID 30S IN THE SONOMA COUNTY VALLEYS. HOWEVER,
ACROSS THE NORTH BAY INTERIOR VALLEYS, LOW TEMPERATURES WERE NOT LOW
ENOUGH ACROSS A WIDE ENOUGH REGION TO PULL THE METAPHORICAL TRIGGER
FOR AN ADVISORY TO GO OUT. NEVERTHELESS, LOW TEMPERATURES ON MONDAY
MORNING ARE STILL EXPECTED TO BE 5 TO 10 DEGREES BELOW THE SEASONAL
AVERAGE ACROSS THE SONOMA AND NAPA COUNTY VALLEYS, WITH PATCHY FROST
POSSIBLE IN ADDITION TO CONTINUING IMPACTS TO VULNERABLE SECTORS,
INCLUDING UNHOUSED PEOPLE, OUTDOOR PETS, AND LIVESTOCK.
LONG TERM
(MONDAY NIGHT THROUGH NEXT SATURDAY)
ISSUED AT 120 PM PST SUN NOV 17 2024
TEMPERATURES WILL REMAIN COLD AND CHILLY INTO MONDAY NIGHT AND
TUESDAY MORNING, WHEN ANOTHER ROUND OF FREEZE AND FROST PRODUCTS ARE
QUITE LIKELY ACROSS THE INTERIOR REGIONS OF THE BAY AREA AND CENTRAL
COAST WITH LOWS IN THE 30S INTO THE LOWER 40S. AFTER COLLABORATION
WITH OUR NEIGHBORS IN SACRAMENTO, FREEZE WATCHES HAVE BEEN ISSUED
FOR THE INTERIOR NORTH BAY AND CENTRAL COAST DUE TO HAZARDOUS COLD
TEMPERATURES, WHICH WILL LIKELY BE UPGRADED TO EITHER FROST
ADVISORIES OR FREEZE WARNINGS TOMORROW.
TEMPERATURES WILL START TO CLIMB LATE ON TUESDAY AND WEDNESDAY AS
MOIST SOUTHERLY FLOW ARRIVES AHEAD OF THE NEXT STORM SYSTEM. A DEEP
UPPER LEVEL LOW WILL DRAG SUBTROPICAL MOISTURE INTO THE AREA AROUND
NORTHERN CALIFORNIA AND SOUTHERN OREGON. SINCE THE LAST FORECAST
UPDATE, CONFIDENCE IN RAINFALL IMPACTS IN THE NORTH BAY HAS
INCREASED AS THE MODEL ENSEMBLE CLUSTERS HAVE COALESCED ONTO A
SOLUTION THAT BRINGS THE BRUNT OF THE MOISTURE TAP INTO THE NORTH
COAST. RAINFALL AMOUNTS HAVE ALSO STARTED TO COME INTO BETTER FOCUS.
FROM EARLY WEDNESDAY INTO THE END OF THURSDAY, AT LEAST 0.5-3" OF
RAIN IN THE NORTH BAY VALLEYS (INCREASING AS YOU GO NORTH) AND A
REASONABLE WORST CASE SCENARIO SEEING RAIN TOTALS 2-5" ACROSS THE
NORTH BAY VALLEYS. THIS GIVES US ENOUGH CONFIDENCE TO BEGIN
MESSAGING THE POTENTIAL FOR THE FIRST PROPER ATMOSPHERIC RIVER OF
THE SEASON. THE WPC HAS ALREADY PLACED MUCH OF THE NORTH BAY IN A
MARGINAL RISK OF EXCESSIVE RAINFALL FOR WEDNESDAY AND THURSDAY,
MEANING THAT THERE'S AT LEAST A 5% CHANCE OF RAINFALL TOTALS
EXCEEDING FLASH FLOOD GUIDANCE, AND THE NORTHERN AND WESTERN PARTS
OF SONOMA COUNTY (BASICALLY EVERYTHING TO THE NORTH AND WEST OF
SANTA ROSA) ARE IN A SLIGHT RISK OF EXCESSIVE RAINFALL (AT LEAST 15%
CHANCE OF EXCEEDING FLASH FLOOD GUIDANCE) ON BOTH DAYS. WE ALSO HAVE
SOME CONCERN FOR NUISANCE FLOODING IN PORTIONS OF THE NORTH BAY
WHERE THE AR AND RESULTANT HIGHER RAINFALL RATES MAY STALL AND
LINGER THROUGH THE LATTER HALF OF THE WEEK. HEADING INTO THE
WEEKEND, THE MOISTURE PLUME WILL BEGIN TO INTERACT WITH AN EXTENSION
OF THE SUBTROPICAL JET, BRINGING THE MOISTURE PLUME TO THE SOUTH AND
EXTENDING RAIN CHANCES THROUGH THE REST OF THE BAY AREA AND THE
CENTRAL COAST INTO THE EARLY PART OF NEXT WEEK.
BE SURE TO PAY CLOSE ATTENTION AND STAY UP TO DATE WITH THE WEATHER
FORECAST OVER THE NEXT FEW DAYS FOR THE LATEST UPDATES AND MOST
ACCURATE INFORMATION.
AVIATION
(00Z TAFS)
ISSUED AT 352 PM PST SUN NOV 17 2024
CIGS HAVE SPREAD OVER MUCH OF THE BAY AREA. CURRENT THINKING STILL
SUPPORTS MORE SCATTERED SHOWERS OVER WIDESPREAD SHOWERS WITH
CONTINUING LOW CONFIDENCE THAT SHOWERS WILL MOVE DIRECTLY OVER
AIRPORTS. THE GOOD NEWS IS THAT ANY SHOWERS THAT DIRECTLY IMPACT
AIRPORTS SHOULD BE LIGHT AND CIGS ARE EXPECTED TO IMPROVE BY LATE
THIS EVENING. THE BAD NEWS IS THAT WITH THE KMUX RADAR CURRENTLY
DOWN, SHOWER BASED AMENDMENTS TO THE TAFS MAY BE LIMITED DEPENDING
ON SATELLITE COVERAGE AND METAR DATA UPDATES. THE FRONT LOOKS MOST
LIKELY TO PASS BETWEEN 03-06Z WITH GUSTY NORTHWEST WINDS EXPECTED TO
CONTINUE OVERNIGHT. WINDS MAY WEAKEN BRIEFLY EARLY TOMORROW MORNING
BEFORE GUSTY WINDS RETURN AGAIN MID TO LATE MORNING.
VICINITY OF SFO...MVFR EXPECTED TO CONTINUE THROUGH THE LATE EVENING
BEFORE CIGS CLEAR OUT QUICKLY AFTER FRONTAL PASSAGE. SCATTERED
SHOWERS BECOME MORE LIKELY HEADING INTO THE EVENING BUT RAIN CHANCES
DROP OFF AND CIGS CLEAR OUT RAPIDLY AFTER FRONTAL PASSAGE. GUSTY
NORTHWEST WINDS ARE EXPECTED TO DEVELOP AROUND THE TIME OF FRONTAL
PASSAGE AND PERSIST THROUGH THE END OF THE TAF PERIOD.
SFO BRIDGE APPROACH...CIGS IMPACTING VISUAL POSSIBLE THROUGH THE TAF
PERIOD.
MONTEREY BAY TERMINALS...VFR BECOMING MVFR THROUGH THE REST OF THE
EVENING. LIGHT, SCATTERED SHOWERS ARE POSSIBLE THROUGH LATE TONIGHT
BUT RAIN CHANCES AND CEILING COVERAGE WILL CLEAR OUT RAPIDLY AFTER
FRONTAL PASSAGE. GUSTY NORTHWEST WINDS RETURN OVERNIGHT AND CONTINUE
THROUGH THE END OF THE TAF PERIOD.
MARINE
(TONIGHT THROUGH NEXT FRIDAY)
ISSUED AT 352 PM PST SUN NOV 17 2024
UNSETTLED WEATHER IS EXPECTED TONIGHT THROUGH EARLY MONDAY AS A
COLD FRONT MOVES THROUGH THE REGION BRINGING SCATTERED SHOWERS AND
GUSTY WINDS. SEAS ARE EXPECTED TO PEAK BETWEEN 10 TO 15 FEET
BEFORE SUBSIDING EARLY NEXT WEEK. A STRONGER AND MORE POTENT
STORM WILL ARRIVE LATE WEEK BRINGING EVEN STRONGER WINDS TO THE
COASTAL WATERS.
BEACHES
ISSUED AT 120 PM PST SUN NOV 17 2024
KING TIDE SEASON IS HERE AND WILL BRING HIGH TIDES UP TO 1-1.5 FT
ABOVE NORMAL TODAY - MONDAY. THE LATE MORNING TIDE CYCLE WILL BE
THE ONE TO WATCH, ESPECIALLY FOR EXPOSED OCEAN BEACHES WHEN HIGH
SURF COMBINES WITH THE KING TIDE. AREAS THAT TYPICALLY FLOOD DURING
KING TIDES WILL VERY LIKELY FLOOD WITHIN A COUPLE HOURS BEFORE TO
A COUPLE HOURS AFTER THE DAILY HIGHEST TIDES. THE NEXT HIGH TIDE
AT SAN FRANCISCO IS EXPECTED ON MONDAY AT 12:11 PM, WITH A HEIGHT
OF 6.60 FEET.
MTR WATCHES/WARNINGS/ADVISORIES
CA...COASTAL FLOOD ADVISORY UNTIL 4 PM PST MONDAY FOR CAZ006-506-508.
FREEZE WATCH FROM LATE MONDAY NIGHT THROUGH TUESDAY MORNING FOR
CAZ504-506-516>518-528.
PZ...SMALL CRAFT ADVISORY UNTIL 3 AM PST MONDAY FOR SF BAY N OF BAY
BRIDGE.
SMALL CRAFT ADVISORY UNTIL 9 PM PST MONDAY FOR PT ARENA TO PT
REYES 0-10 NM-PT REYES TO PIGEON PT 0-10 NM.
SMALL CRAFT ADVISORY UNTIL 9 PM PST MONDAY FOR PIGEON PT TO PT
PINOS 0-10 NM-PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM.
SMALL CRAFT ADVISORY UNTIL 3 PM PST TUESDAY FOR PIGEON PT TO PT
PINOS 10-60 NM-PT ARENA TO PT REYES 10-60 NM.
SHORT TERM...DIALH
LONG TERM....DIALH
AVIATION...KENNEDY
MARINE...MM
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