894
FXUS66 KMTR 060551
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
951 PM PST MON JAN 5 2026
..NEW UPDATE, AVIATION, MARINE
KEY MESSAGES
UPDATED AT 210 PM PST MON JAN 5 2026
- RAINFALL CONTINUES THIS AFTERNOON FOR NORTH BAY AND BAY AREA
REGIONS, MORE UNCERTAIN ALONG CENTRAL COAST GOING INTO TONIGHT.
- CONDITIONS IMPROVE TONIGHT, DRY TOMORROW. SLIGHT CHANCE OF VERY
LIGHT, BRIEF SHOWERS OR DRIZZLE WEDNESDAY AM. OTHERWISE DRY
THROUGH THE REST OF THE WEEK AND THROUGH THE WEEKEND.
- CHILLY OVERNIGHT LOWS BEGINNING WEDNESDAY NIGHT THROUGH SUNDAY
NIGHT; WIDESPREAD LOWS IN THE 30S, LOWER 40S ALONG THE COAST.
UPDATE
ISSUED AT 950 PM PST MON JAN 5 2026
IT HAS BEEN A HECTIC LAST COUPLE OF HOURS HERE AT THE OFFICE WITH
THE FRONTAL RAIN BAND SLOWLY MAKING ITS WAY TO THE EAST. NUMEROUS
FLOOD ADVISORIES HAVE BEEN ISSUED AND TRAINING SHOWERS ARE
CONTINUING TO VEX PARTS OF OUR REGION, INCLUDING THE SANTA CRUZ
MOUNTAINS AND THE EAST BAY. HAVEN'T HAD MUCH TIME TO DO A DEEP DIVE
INTO THE SYNOPTICS YET, BUT IT LOOKS LIKE THE LOW PRESSURE SYSTEM
SETTLING OFF THE COAST OF THE NORTH BAY WAS IN JUST THE RIGHT
ORIENTATION TO BRING RAINFALL TOTALS TOWARDS THE UPPER END OF THE
RAINFALL FORECASTS. AS I WRITE THIS, SELECTED RAINFALL TOTALS FROM
THE LAST 24 HOURS ACROSS THE REGION INCLUDE: 1.69 INCHES AT THE
SONOMA COUNTY AIRPORT, 0.47 INCHES AT THE NAPA COUNTY AIRPORT, 0.84
INCHES AT DOWNTOWN SAN FRANCISCO, 0.77 INCHES AT OAKLAND MUSEUM,
1.03 INCHES AT THE SAN FRANCISCO AIRPORT, 0.37 INCHES AT SAN JOSE
AIRPORT, 2.91 INCHES AT THE BEN LOMOND MOUNTAIN RAWS, AND 0.53
INCHES AT THE MONTEREY AIRPORT. EXPECTING THE RAIN BAND TO SLOWLY
MOVE TO THE EAST AND DISSIPATE THROUGH THE OVERNIGHT HOURS. BY
TUESDAY MORNING, HIGH RESOLUTION MODEL OUTPUT SUGGESTS THAT ISOLATED
LINGERING SHOWERS WILL REMAIN.
DIALH
SHORT TERM
ISSUED AT 210 PM PST MON JAN 5 2026
(THIS EVENING THROUGH TUESDAY)
CURRENT RADAR SHOWING A LINE OF LIGHT-TO-MODERATE RAINFALL
EXTENDING ALONG THE WARM CONVEYOR BELT FROM SOUTHWEST TO NORTHEAST.
AS WE GET INTO THE AFTERNOON HOURS, THIS BAND WILL GRADUALLY
SHIFT INTO THE BAY AREA WHERE THE LINE WILL SHIFT MORE TO A SOUTH
TO NORTH ORIENTATION. THIS WILL PROMOTE WHAT WILL APPEAR TO BE A
STALLING BEHAVIOR WHERE THE RAINFALL WILL "TRAIN" OVER AREAS OF
THE SF PENINSULA INTO THIS EVENING. AS SUCH, THERE WILL BE AN
URBAN AND SMALL STREAM FLOODING THREAT ACROSS THE BAY AREA THROUGH
THE EVENING COMMUTE. THE HARDEST HIT AREAS ARE LIKELY TO BE IN THE
SANTA CRUZ MTNS WHERE THE VERY EFFICIENT WARM RAIN PROCESS HAS
BEEN OCCURING SINCE THE LATE MORNING HOURS, ESPECIALLY WEST OF HWY
17. THIS PRECURSOR RAIN FOLLOWED BY THE HEAVIER RAIN FALL ALONG
THE COLD FRONT MAY POSE A BIGGER RISK FOR FLOODING AND SHALLOW
LANDSLIDES. AFTER SUNSET, THIS BAND OF RAIN WILL START TO IMPACT
THE MONTEREY AREA AND PORTIONS OF THE CENTRAL COAST WHERE THERE
WILL BE ANOTHER ISOLATED INCREASED FLOODING AND SHALLOW LANDSLIDE
THREAT THROUGH THE OVERNIGHT HOURS. BOTH OF THESE AFOREMENTIONED
AREAS OF INTEREST (SANTA CRUZ MTNS AND MONTEREY/CARMEL AREAS)
COULD SEE ANOTHER QUICK 1-2" OVER A THREE HOUR PERIOD DEPENDING ON
WHERE SOME OF THE HEAVIER PRECIP TRACKS WITHIN THE BAND OF
MOISTURE.
BY THE EARLY MORNING HOURS, THINGS START TO TAPER OFF AND
CONDITIONS IMPROVE. MOSTLY DRY THROUGH TUESDAY WITH JUST A FEW
LINGERING SHOWERS DURING THE EARLY MORNING.
LONG TERM
ISSUED AT 210 PM PST MON JAN 5 2026
(TUESDAY NIGHT THROUGH NEXT SUNDAY)
BEYOND TUESDAY MORNING, THERE IS HIGH CONFIDENCE IN A BROAD, HIGH
AMPLITUDE RIDGE PATTERN DEVELOPING OVER THE WEST COAST. THIS WILL
PROMOTE DRY CONDITIONS AND MOSTLY CLEAR SKIES ACROSS THE REGION
THROUGH THIS WEEKEND AND AT LEAST THE BEGINNING OF NEXT WEEK. THE
ONLY NOTABLE MENTION GOING FORWARD AFTER TUESDAY WILL BE CHILLY
OVERNIGHT TEMPERATURES WEDNESDAY NIGHT TO SUNDAY NIGHT AS SKIES
CLEAR OUT. THE PEAK OF THE COLD TEMPS CAN BE EXPECTED BEGINNING
THURSDAY MORNING INTO SUNDAY MORNING WITH WIDESPREAD LOWS IN THE
30S WITH LOWER 40S ALONG THE IMMEDIATE COAST.
AVIATION
(06Z TAFS)
ISSUED AT 950 PM PST MON JAN 5 2026
THE BAND OF RAIN CURRENTLY COMING THROUGH THE BAY AREA AND CENTRAL
COAST, WHICH IS CURRENTLY BRINGING LOW-END VFR-IFR CONDITIONS ACROSS
THE REGION, WILL SLOWLY MOVE EASTWARDS AND DISSIPATE THROUGH THE
OVERNIGHT HOURS. BREEZY SOUTHERLY WINDS WILL PREVAIL IN FRONT OF AND
WITHIN THE BAND. AS THE BAND CLEARS TUESDAY MORNING, CEILINGS WILL
RISE TO VFR, AND WINDS WILL CONTINUE TO BE LIGHT THROUGH THE TAF
PERIOD. SOME RADIATIVE LOW STRATUS FORMATION IS POSSIBLE TUESDAY
NIGHT AT AND AFTER THE END OF THE TAF PERIOD, BUT CONFIDENCE IS
CURRENTLY RATHER LOW.
VICINITY OF SFO... RAINY CONDITIONS WITH LOW-END VFR-MVFR CEILINGS
SHOULD CONTINUE THROUGH THE NEXT COUPLE OF HOURS WITH THE RAIN BAND
MOVING AWAY FROM THE TERMINAL AREA. SCATTERED SHOWERS WILL CONTINUE
THROUGH THE NIGHT AND DISSIPATE THROUGH TUESDAY MORNING. BEHIND THE
RAIN BAND, CEILINGS SHOULD LIFT TO VFR AND WINDS SHOULD REMAIN
LIGHT THROUGH THE END OF THE TAF PERIOD.
SFO BRIDGE APPROACH... SIMILAR TO SFO.
MONTEREY BAY TERMINALS... RAINY CONDITIONS THROUGH THE NEXT COUPLE
OF HOURS WITH LOW-END VFR CEILINGS. BREEZY SOUTHEAST WINDS WILL
CONTINUE THROUGH THE PRE-DAWN HOURS TUESDAY MORNING AT SNS, WITH THE
WINDS TURNING LIGHT ACROSS THE REGION THROUGH TUESDAY AS CEILINGS
LIFT.
MARINE
(TONIGHT THROUGH NEXT SUNDAY)
ISSUED AT 950 PM PST MON JAN 5 2026
A LOW PRESSURE SYSTEM OFF THE COAST IS BRINGING UNSETTLED WEATHER
WHILE A MODERATE TO FRESH SOUTHERLY BREEZE GENERATES ROUGH WIND
WAVES. THIS SYSTEM WILL SLIDE SOUTH OVER THE NEXT 24 HOURS, WITH
GRADUAL IMPROVEMENT THROUGH THE DAY TUESDAY. NORTHERLY WINDS
RETURN WEDNESDAY AND INCREASE TO A STRONG BREEZE BY THURSDAY
MORNING. THESE WINDS COINCIDE WITH A VERY HIGH NW SWELL, BUILDING
VERY ROUGH COMBINED SEAS THURSDAY.
MTR WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 3 AM PST TUESDAY FOR PT PINOS TO PT
PIEDRAS BLANCAS 0-10 NM.
SHORT TERM...BEHRINGER
LONG TERM....BEHRINGER
AVIATION...DIALH
MARINE...FLYNN
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