415
FXUS66 KMTR 301216
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
ISSUED BY NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
416 AM PST THU JAN 30 2025
..NEW AVIATION, MARINE
SYNOPSIS
ISSUED AT 300 AM PST THU JAN 30 2025
A PATTERN CHANGE WILL ARRIVE ON FRIDAY, LEADING TO AN EXTENDED
PERIOD OF WET WEATHER. IT IS LOOKING MORE LIKELY THAT AN
ATMOSPHERIC RIVER WILL AFFECT NORTHERN CA, INCLUDING THE BAY AREA
AND PERHAPS PORTIONS OF THE CENTRAL COAST. THE NORTH BAY WILL
LIKELY RECIEVE THE HIGHEST AMOUNTS OF RAIN. FORECAST RAINFALL
AMOUNTS HAVE ALSO BEEN INCREASED FOR FOR THE MORE SOUTHWARD AREAS.
STAY TUNED TO THE FORECAST, AS THERE MAY WELL BE ADDITIONAL
NUANCES TO THE FORECAST RAINFALL TOTALS.
SHORT TERM
TODAY AND THIS EVENING.
ISSUED AT 300 AM PST THU JAN 30 2025
UPPER LEVEL RIDGING WILL HOLD THROUGH MUCH OF THE DAY, BUT WILL
BEGIN TO FLATTEN LATER THIS EVENING AS AN UPPER LEVEL TROF MOVES
INTO THE PAC NW. COASTAL STRATUS WILL REMAIN IN PLACE THROUGH THE
MORNING HOUR, WITH INLAND AREAS CLEARING BY THE AFTERNOON. STRATUS
CLEARING FOR THE COASTAL AREAS IS UNCERTAIN AND ITS POSSIBLE IT
WIL BE CLOUDY ALL DAY WHICH WOULD RESULT IN LOWER THAN FCST
TEMPERATURES. TONIGHT, SOME STRATUS MAY SLITHER INLAND, BUT DUE TO
THE PATTERN CHANGE AND APPROACHING FRONT IT SHOULD NOT BE AS
EXPANSIVE AS IT IS TODAY.
LONG TERM
(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 300 AM PST WED JAN 30 2025
THE STORM DOOR OPENS ON FRIDAY ALLOWING FOR AN ATMOSPHERIC RIVER
TO SET UP OVER THE AREA. TRENDS HAVE SHIFTED SOUTHWARD, POINTING
INITIALLY AT S OR AND N CA THE MAIN AXIS IS NOW AIMED N CA AND THE
BAY AREA. ENSEMBLES NOW SHOW MUCH OF THE BAY AREA, AND EVEN THE
CENTRAL COAST, UNDER PWATS BETWEEN .75 AND 1.25 INCHES. ENSEMBLE
BASED PRECIPITATION TOTALS HAVE ALSO INCREASED, ESPECIALLY ACROSS
THE NORTH BAY, SAN FRANCISCO AND EAST BAY AREAS. GIVEN THE INCREASED
CONFIDENCE OF HIGHER RAINFALL AMOUNTS (AND A POTENTIAL FOR EVEN
GREATER AMOUNTS), THE WPC HAS PEPPERED IN A MIX OF MARGINAL (LEVEL
1 OF 4) AND SLIGHT (LEVEL 2 OF 4) RISKS OF EXCESSIVE RAINFALL FOR
THE FRIDAY THROUGH MONDAY PERIOD (DAYS 2 TO 5). AT THE TIME OF
THIS FORECAST PACKAGE LOOK TO BE SATURDAY (DAY 3) AND MONDAY (DAY
5). FOR SATURDAY, THE WPC PLACED MUCH OF THE BAY AREA AND SANTA
CRUZ COUNTY IN A SLIGHT RISK (LEVEL 2 OF 4) FOR EXCESSIVE RAIN AND
ON MONDAY THE SLIGHT RISK ALSO INCLUDES NORTHERN SONOMA COUNTY.
THIS FORECAST WILL CONTINUE TO BE FINE TUNED AS WE GET INTO THE
HI-REZ MODEL GUIDANCE TERRITORY, BE SURE TO KEEP UP WITH THE
LATEST FORECAST PRODUCTS AS RAINFALL TOTALS AND PEAKS WILL BE FINE
TUNED, WHICH COULD RESULT IN CHANGES IN TIMING AND AREAS OF THE
EXCESSIVE RAINFALL OUTLOOKS.
AVIATION
(12Z TAFS)
ISSUED AT 300 AM PST WED JAN 30 2025
WIDESPREAD MVFR-IFR STRATUS PERSISTS OVER THE TERMINALS. LIFR
CONDS HAVE DEVELOPED IN THE NORTH BAY BUT WILL LAST ONLY A SHORT
AMOUNT OF TIME BEFORE LIFTING TO MVFR VALUES. INLAND TERMINALS
WILL CLEAR OUT IN THE LATE MORNING TO EARLY AFTERNOON HOURS. LOWER
CONFIDENCE IN THE CLEARING FORECAST FOR THE COASTAL TERMNIAL WHERE
THE MDLS DISAGREE ON THE STRATUS EVOLUTION. HAVE KEPT THE PREVIOUS
FORECAST OF A LIFTING TO VFR WITH WITH MID-LEVEL CIGS, BUT THE
PERSISTENCE FORECAST WOULD SUGGEST THE COASTAL REGIONS BEING
SOCKED IN THROUGH THE DAY. MONITOR FUTURE TAF ISSUANCES FOR
UPDATES. LIGHT ONSHORE FLOW WILL DEVELOP THIS AFTERNOON. WINDS
WILL TURN TO THE SW LATER THIS EVENING. SOME MDLS ARE SHOWING A
TRANSITORY RETURN OF MVFR CIGS BEFORE THE SW WINDS COME, BUT
CONFIDENCE IS LOW, AS IS THE POSSIBILITY OF SCATTERED SHOWERS
AHEAD OF THE MAIN RAIN BAND EARLY FRIDAY MORNING, PARTICULARLY NI
THE NORTH BAY AND COASTAL RANGES. ANY WIDESPREAD RAIN CHC ARE
EXPECTED TO COME NEAR TO OR AT THE END OF THE TAF PERIOD.
VICINITY OF SFO...MVFR-IFR STRATUS THROUGH THE AFTERNOON HOURS.
LIGHT WESTERLY FLOW THIS AFTERNOON, TURNING SOUTHERLY LATER IN THE
EVENING AND OVERNIGHT AT MID-LEVEL CLOUDS STREAM THROUGH. SOME
SCATTERED SHOWERS ARE POSSIBLE FRIDAY MORNING, BUT THE MAIN THRUST
IS NOT EXPECTED UNTIL AFTER THE TAF PERIOD.
SFO BRIDGE APPROACH...SIMILAR TO SFO.
MONTEREY BAY TERMINALS...MVFR CIGS THROUGH LATE MORNING AT
EARLIEST. MODERATE CONFIDENCE THAT CIGS LIFT TO LOW VFR HGTS BUT
BKN-OVC CONDS ARE EXPECTED THROUGH THE PERIOD. LIGHT WEST-
NORTHWEST FLOW THIS AFTERNOON, WITH DRAINAGE WINDS POSSIBLE IN THE
EVENING AS CIGS LOWER TO MVFR VALUES. ANY IMPACTS FROM THE STORM
SYSTEM ARE NOT EXPECTED UNTIL WELL AFTER THE CURRENT TAF PERIOD
FRIDAY AFTERNOON.
MARINE
(TODAY THROUGH NEXT TUESDAY) ISSUED AT 300 AM PST THU JAN 30 2025
WINDS AND SEAS TO STAY RELATIVELY CALM AND LIGHT THROUGH FRIDAY.
UNSETTLED WEATHER RETURNS FRIDAY INTO EARLY NEXT WEEK AS AN UPPER
LEVEL LOW BRINGS GUSTY WINDS TO THE NORTHERN WATERS, CREATING
HAZARDOUS CONDITIONS FOR SMALL CRAFTS. EXPECT WIDESPREAD RAIN OVER
THE WATERS STARTING FRIDAY INTO THE WEEKEND.
MTR WATCHES/WARNINGS/ADVISORIES
.TDAY...NONE.
PUBLIC FORECAST: 01
AVIATION: 02
MARINE: 03
VISIT US AT WWW.WEATHER.GOV/SANFRANCISCO
FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page