297
FXUS66 KMTR 050929
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
129 AM PST MON JAN 5 2026
..NEW SHORT TERM, LONG TERM, BEACHES
KEY MESSAGES
UPDATED AT 1203 AM PST MON JAN 5 2026
- RAIN RETURNS TODAY WITH URBAN AND MINOR RIVER FLOODING
POSSIBLE, PARTICULARLY IN THE NORTH BAY
- ONE LAST DAY WITH COASTAL FLOODING FROM KING TIDES AND STORM
SURGE IN THE SAN FRANCISCO BAY
- HAZARDOUS BEACH CONDITIONS THURSDAY - FRIDAY
- DRIER WEATHER MOVES IN TUESDAY AND REMAINS THROUGH NEXT WEEK
- COLD MORNING TEMPERATURES STARTING THURSDAY
SHORT TERM
ISSUED AT 1203 AM PST MON JAN 5 2026
(TODAY AND TONIGHT)
IN A WORD, WET. THE NEXT ORGANIZED BAND OF SHOWERS WILL MOVE
THROUGH WITH THE PASSAGE OF A COLD FRONT TODAY. THE CURRENT RADAR
DATA SHOWS A PRETTY WELL-BEHAVED WARM SECTOR RAIN BAND COMING INTO
RANGE. THERE HAVE BEEN A FEW LIGHTNING STRIKES OVER THE OCEAN
BEHIND THE FRONT NEAR A MATURE EXTRATOPRICAL CYCLONE. IT'S UNCLEAR
IF THE CONVECTION WILL BE AS DEEP OVER LAND WHERE THE INSTABILITY
IS WEAKER, BUT THIS LOW PRESSURE SYSTEM WILL ENHANCE THE RAIN TO
SOME DEGREE THIS AFTERNOON. THE NORTH BAY WILL BE HIT THE HARDEST
TODAY, WITH 1-2" EXPECTED IN THE LOWER ELEVATIONS, AND UP TO 4" IN
THE MOUNTAINS. THE RAIN WILL START THERE AS EARLY AS 2 AM, AND
CONTINUE OFF-AND-ON THROUGH THE ENTIRE DAY. MINOR URBAN AND SMALL
STREAM FLOODING IS EXPECTED, AND THERE IS A SLIGHT CHANCE FOR THE
LARGER RIVERS TO REACH MINOR FLOOD STAGE. THE REST OF THE BAY
AREA WILL GET LESS RAIN. THERE'S QUITE A BIT OF DISAGREEMENT
BETWEEN THE MODELS ON HOW MUCH LESS, WITH HIGH RESOLUTION GUIDANCE
MUCH DRIER THAN GLOBAL MODELS. OUTSIDE OF THE NORTH BAY WE COULD
GET ANYWHERE FROM LESS THAN 1/10" OR UP TO 3". THE ECMWF ENSEMBLE
SPREAD RANGES FROM 0.25" TO 2.5" AT SFO. THAT'S A SIGNIFICANT
AMOUNT OF UNCERTAINTY TO PUT IN THE SHORT TERM SECTION, BUT WITH
THE HEAVIER LINE OF SHOWERS EXPECTED TO STALL SOMEWHERE ALONG THE
COAST, IT MAKES SENSE. THE IQR IS MORE REASONABLE AT 1-1.5", BUT
THE OUTLIER MEMBERS ARE JUST AS LIKELY AS ANY OTHER SOLUTION IN
THE ENSEMBLE. CUT-OFF LOW PRESSURE SYSTEMS ARE HARD TO FORECAST
BECAUSE THERE IS NOTHING OBVIOUS MOVING THEM ALONG. IT'S LIKE A
TODDLER IN A CANDY STORE THAT JUST LET GO OF THEIR PARENT'S HAND.
NOBODY KNOWS WHAT WILL HAPPEN. THE EXACT TRACK OF THIS DRIFTING
FEATURE WILL HAVE A BIG INFLUENCE ON THE RAIN TOTALS TODAY. THE
SYSTEM SHOULD DRIFT SOMEWHERE NEAR THE COAST OF THE BAY AREA THIS
AFTERNOON BEFORE BECOMING VERTICALLY STACKED, DRIFTING SOUTH, AND
WEAKENING OVERNIGHT. THIS WILL COINCIDE WITH THE PASSAGE OF A
SHARP TROUGH IN THE JET STREAM, FLIPPING UPPER LEVEL WINDS NEARLY
180 DEGREES FROM SW TO NE. THAT CHANGES EVERYTHING FOR THE REST
OF THE WEEK.
LONG TERM
ISSUED AT 1203 AM PST MON JAN 5 2026
(TUESDAY THROUGH SUNDAY)
IN A WORD, DRY. AS THE UPPER LEVEL WINDS FLIP TO NORTHERLY
FOLLOWING PASSAGE OF THE TROUGH AXIS, DRIER, MORE STABLE AIR WILL
START TO MOVE IN. TUESDAY IS A TRANSITION DAY BETWEEN THE WET
STORMY PATTERN WE'VE HAD FOR THE LAST WEEK, AND MUCH DRIER WEATHER
THAT ARRIVES IN EARNEST WEDNESDAY. BEFORE WE GET THERE, DON'T BE
SURPRISED TO SEE A COUPLE SHOWERS ON TUESDAY, BUT NOTHING
COMPARABLE TO THE LAST FEW DAYS. THERE SHOULDN'T BE ANY MORE
FLOODING CONCERNS, ESPECIALLY AFTER THE SUN COMES UP. A WEAK
TROUGH WILL MOVE THROUGH ON WEDNESDAY, BUT SHOULDN'T BRING MORE
THAN CLOUDS. BY THURSDAY, A 500 MB RIDGE WILL BUILD AND THE SKIES
WILL CLEAR. THE PW WILL DROP BELOW 0.4" (25TH PERCENTILE), WHERE
IT COULD STAY FOR THE NEXT 2 WEEKS. THE CLEAR SKIES WILL BRING
COLD MORNING TEMPERATURES WITH INTERIOR AREAS DROPPING INTO THE
30S FOR THE FIRST TIME SINCE LATE DECEMBER. AN INSIDE SLIDER
PATTERN COULD DEVELOP AND WILL BRING SOME OFFSHORE WINDS THIS
WEEKEND BEFORE ANOTHER RIDGE BUILDS NEXT WEEK.
AVIATION
(06Z TAFS)
ISSUED AT 937 PM PST SUN JAN 4 2026
GENERALLY VFR CONDITIONS WITH MID- TO HIGH LEVEL CLOUDS ACROSS THE
REGION, WITH ISOLATED SHOWERS PERSISTING EARLY TONIGHT. WIDESPREAD
RAIN RETURNS AFTER MONDAY MORNING WITH GENERALLY MODERATE RAIN
RATES, PARTICULARLY FOR THE NORTH BAY TERMINALS, LOCALIZED HEAVY
RAIN, AND DIMINISHED VISIBILITIES EXPECTED. SOUTHERLY FLOW CONTINUES
THROUGH THE TAF PERIOD, WITH WINDS REMAINING LIGHT OVERNIGHT WITH
PERIODS OF GUSTY WINDS EXPECTED AS THE MAIN RAIN BAND COMES THROUGH.
VISIBILITIES AND CEILINGS WILL DROP BELOW THE TAF FORECAST IF A
STRONG SHOWER MOVES OVER A PARTICULAR TERMINAL.
VICINITY OF SFO... VFR WITH MID- TO HIGH LEVEL CLOUDS THROUGH THE
NEXT FEW HOURS BEFORE LIGHT TO MODERATE RAIN RETURNS MONDAY MORNING,
WHEN CONDITIONS HOVER NEAR THE MVFR-VFR THRESHOLD. SHOWERS WILL
AGAIN DIMINISH IN INTENSITY MONDAY EVENING THROUGH THE END OF THE
TAF PERIOD AS CEILINGS LIFT ABOVE MVFR THRESHOLDS. VISIBILITIES AND
CEILINGS WILL DROP BELOW THE TAF FORECAST IF A STRONG SHOWER MOVES
OVER SFO.
SFO BRIDGE APPROACH... SIMILAR TO SFO.
MONTEREY BAY TERMINALS...LIGHT WINDS OVERNIGHT AS GENERALLY VFR-MVFR
CONDITIONS AND ISOLATED TO SCATTERED SHOWERS CONTINUE. SOUTHERLY
WINDS BUILD OVERNIGHT AS A FRONTAL RAIN BAND APPROACHES, WITH THE
MAIN IMPACTS ARRIVING MONDAY MORNING, INCLUDING GUSTY SOUTHEAST
WINDS AND LIGHT TO MODERATE RAIN. RAIN INTENSITY SHOULD DIMINISH
MONDAY AFTERNOON THROUGH AND AFTER THE END OF THE TAF PERIOD. IF
MORE INTENSE SHOWERS DEVELOP OVER THE REGION, EXPECT VISIBILITIES
AND CEILINGS TO DROP BELOW THE FORECAST WITHIN THE TAF.
MARINE
(TONIGHT THROUGH NEXT SATURDAY)
ISSUED AT 937 PM PST SUN JAN 4 2026
ISOLATED TO SCATTERED SHOWERS CONTINUE OVERNIGHT WITH WIDESPREAD
RAINFALL AND A SLIGHT CHANCE FOR THUNDERSTORMS DEVELOPING ON
MONDAY. SEAS REMAIN MODERATE TO ROUGH TONIGHT UNDER SOUTHWESTERLY
WINDS WITH STRONG TO GALE FORCE GUSTS. WINDS DIMINISH BY EARLY
NEXT WEEK BUT ARE EXPECTED TO BUILD AGAIN, ALONG WITH SEAS, DURING
THE LATE WEEK AS LONG PERIOD NORTHWESTERLY SWELL RETURNS.
BEACHES
ISSUED AT 1203 AM PST MON JAN 5 2026
ONE LAST DAY OF COASTAL FLOODING FROM KING TIDES AND STORM SURGE.
WHILE LOWER THAN PREVIOUS DAYS, THE HIGH TIDE WILL STILL BE
ROUGHLY 1.2 FEET ABOVE NORMAL, BRINGING MINOR IMPACTS TO LOW-LYING
AREAS NEAR SHORELINES AND TIDAL WATERWAYS DURING HIGH TIDE. THE
COASTAL FLOOD ADVISORY IS IN EFFECT THROUGH 3 PM TODAY FOR THE SAN
FRANCISCO BAY AND SAN PABLO BAY. HIGH TIDE IS EXPECTED IN SAN
FRANCISCO AT 12:08 PM MONDAY. HIGH TIDE TIMING VARIES UP TO 90
MINUTES LATER THROUGH THE SAN FRANCISCO BAY.
MTR WATCHES/WARNINGS/ADVISORIES
CA...COASTAL FLOOD ADVISORY UNTIL 3 PM PST THIS AFTERNOON FOR CAZ006-
506-508.
PZ...SMALL CRAFT ADVISORY UNTIL 9 PM PST THIS EVENING FOR MRY BAY.
SMALL CRAFT ADVISORY UNTIL 3 PM PST THIS AFTERNOON FOR PT ARENA
TO PT REYES 0-10 NM-PT REYES TO PIGEON PT 0-10 NM.
SMALL CRAFT ADVISORY UNTIL 9 PM PST THIS EVENING FOR PIGEON PT
TO PT PINOS 0-10 NM.
SMALL CRAFT ADVISORY UNTIL 9 AM PST THIS MORNING FOR PT ARENA TO
PT REYES 10-60 NM-PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM.
GALE WARNING FROM 9 AM THIS MORNING TO 3 PM PST THIS AFTERNOON
FOR PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM.
SMALL CRAFT ADVISORY FROM 9 AM THIS MORNING TO 9 PM PST THIS
EVENING FOR PIGEON PT TO PT PINOS 10-60 NM.
SHORT TERM...FLYNN
LONG TERM....FLYNN
AVIATION...DIALH
MARINE...DIALH
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