548
FXUS66 KMTR 031812
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
1012 AM PST SAT JAN 3 2026
..NEW AVIATION
KEY MESSAGES
UPDATED AT 1201 AM PST SAT JAN 3 2026
- HIGH ASTRONOMICAL TIDES COMBINED WITH STORM SURGE WILL BRING
SUBSTANTIAL TIDAL FLOODING THROUGH SUNDAY
- CHANCE OF THUNDERSTORMS THROUGH THE WEEKEND
- HAZARDOUS BEACH CONDITIONS SUNDAY
- DAILY RAIN SHOWERS EXPECTED THROUGH MONDAY
UPDATE
ISSUED AT 904 AM PST SAT JAN 3 2026
OUTSIDE OF A FEW HEAVIER RAIN SHOWERS THIS MORNING MOVING ACROSS
PORTIONS OF THE REGION, CONDITIONS HAVE BEEN RELATIVELY QUITE.
HOWEVER, WE HAVE BEEN SEEING SEVERAL REPORTS OF SHALLOW LANDSLIDE
ACROSS THE NORTH BAY AS SOILS HAVE BECOME SATURATED. MARK WEST
CREEK, COLGAN CREEK, WIGGINS CREEK, AND SANTA ROSA CREEK IN WESTERN
SONOMA COUNTY ARE IN ACTION STAGE DUE TO RUNOFF FROM RECENT
RAINFALL. ADDITIONALLY, LAW ENFORCEMENT HAS REPORTED FLOODING IN AND
AROUND VALLEY FORD. A FLOOD ADVISORY REMAINS IN EFFECT FOR THOSE
AREAS THROUGH 10 AM PST. LASTLY, WE HAVE CANCELLED THE WIND ADVISORY
AS SOUTHERLY WINDS HAVE FALLEN BELOW CRITERIA. THE HIGHEST PEAKS
ACROSS THE REGION ARE STILL GUSTING BETWEEN 40-55 MPH.
THE THREAT FOR THUNDERSTORM LATE THIS MORNING AND INTO THE AFTERNOON
PERSISTS, BUT MORE ON THAT CAN BE SEEN IN THE SHORT TERM DISCUSSION
BELOW.
RGASS
SHORT TERM
ISSUED AT 1201 AM PST SAT JAN 3 2026
(TODAY AND TONIGHT)
THE OCCLUDED FRONT IS JUST OFF THE COAST, AND THE TRIPLE
POINT SHOULD MAKE LANDFALL IN THE BAY AREA AROUND 4 AM. THE MORE
ORGANIZED BAND OF RAIN ASSOCIATED WITH THIS FRONTAL PASSAGE HAS
REACHED THE NORTH BAY AND WILL PUSH SOUTH THROUGH THE EARLY MORNING
HOURS. OVERALL THE RAIN HAS BEEN SOMEWHAT UNDERWHELMING COMPARED TO
OUR EXPECTATIONS. OUTSIDE OF THE MOUNTAINS, NOWHERE HAS RECORDED
MORE THAN 1" OF RAIN, WITH LESS THAN 1/4" ACROSS THE SF PENINSULA,
EAST BAY, AND SOUTH BAY. WHILE WE HAVEN'T SEEN THUNDERSTORMS YET,
WE'VE JUST STARTED TO SEE 40 DBZ AT THE -10C LEVEL, INCREASING
CONFIDENCE THAT WE'RE APPROACHING THE ICE CONTENT NECESSARY TO
GENERATE LIGHTNING. AFTER THE FRONT PASSES THE RAIN WILL
TRANSITION TO SCATTERED SHOWERS, SOME OF WHICH COULD BE STRONG. WE
HAVE A RENEWED CHANCE FOR THUNDERSTORMS IN THE MORE UNSTABLE
ATMOSPHERE THROUGH THE DAY SATURDAY, PARTICULARLY IN THE NORTH
BAY. A RAP13 POINT SOUNDING AT SANTA ROSA SHOWS THE INSTABILITY
PEAKING AROUND 1 PM. ACCORDING TO THIS MODEL, THE SURFACE BASED
CAPE REACHES AN IMPRESSIVE 676 J/KG, WITH STEEP LOW-LEVEL LAPSE
RATES (-7.4 C/KM), DECENT 0-1 KM SHEAR (25 KT) IN A SLIGHTLY
CURVED HODOGRAPH, AND LOW LCL HEIGHTS (394M). IF WE CAN MANAGE TO
FIND A TRIGGER TO TAP INTO THIS ENERGY IN AN ORGANIZED MANNER, A
LINE OF THUNDERSTORMS COULD DEVELOP ACROSS THE NORTH BAY IN THE
AFTERNOON AND PUSH SOUTH THROUGH THE EVENING AHEAD OF THE NEXT
FRONTAL PASSAGE SUNDAY MORNING. WITH THE MODERATE SHEAR, WE CAN'T
RULE OUT SEVERE THUNDERSTORMS. THERE IS ONLY A MARGINAL CHANCE,
BUT DAMAGING WIND GUSTS AND SHORT LIVED TORNADOES ARE THE PRIMARY
HAZARD IF ANY THUNDERSTORMS CAN MANAGE TO BECOME SEVERE.
THE SUNDAY FRONT WILL BRING SIMILAR IMPACTS TO THE ONGOING SYSTEM,
ALTHOUGH THE RAIN WILL CONTINUE PAST DAWN, SO THE IMPACT FROM THE
RAIN WILL LIKELY BE HIGHER. WINDS, ON THE OTHER HAND, WILL DECREASE
TO A MODERATE BREEZE, AND THE THUNDERSTORM THREAT WILL ABATE
THROUGH THE DAY. WHILE RIVER FLOODING ISN'T A MAJOR CONCERN, THE
USGS IS REPORTING SATURATED SOILS. IF ANY HEAVY SHOWERS BRING HIGH
RAIN RATES THEY COULD TRIGGER SHALLOW LANDSLIDES.
LONG TERM
ISSUED AT 1201 AM PST SAT JAN 3 2026
(SUNDAY THROUGH FRIDAY)
SHOWERS WITH A SLIGHT CHANCE OF THUNDERSTORMS WILL PERSIST SUNDAY
NIGHT INTO THE BEGINNING OF THE NEW WORK WEEK, ESPECIALLY FOR THE
NORTH BAY. THE UPPER LEVEL LOW CURRENTLY RESPONSIBLE FOR OUR WINDY
AND RAINY WEATHER OVERNIGHT, WILL LIFT NORTH DURING THE DAY TODAY
AND BE RE-ABSORBED BY YET ANOTHER DISTURBANCE OFF THE COAST OF THE
PACIFIC NORTHWEST. THE TROUGH ASSOCIATED WITH THE EXITING LOW, WILL
BE REINVIGORATED OVER THE NEXT 48HRS AND BRING ANOTHER ROUND OF
WIDESPREAD RAINFALL MONDAY INTO EARLY TUESDAY. THE COASTAL RANGES
WILL BE FAVORED FOR THE HIGHEST RAIN TOTALS BUT THE SPIGOT DOESN'T
APPEAR TO SHUT OFF UNTIL WEDNESDAY WHEN WE SEE AMPLIFIED RIDGING
BEGIN TO BUILD OVER THE EASTERN PACIFIC IN THE WAKE OF THE FINAL
UPPER LOW SHIFTING SOUTH OFFSHORE ON TUESDAY. THE COASTAL RANGES MAY
SEE 1-2" OF RAINFALL MONDAY INTO TUESDAY WITH LESSER AMOUNTS FOR THE
REMAINDER OF OUR AREA, AROUND 0.25"-0.75" WHERE IT DOES RAIN.
THERE'S A CHANCE NEXT WEEKEND COULD BE A GOOD ONE, WITH CLIMATE
PREDICTION CENTER HIGHLIGHTING THE POSSIBILITY IN THE 6-10 DAY
OUTLOOK.
AVIATION
(18Z TAFS)
ISSUED AT 1012 AM PST SAT JAN 3 2026
SCATTERED SHOWERS ARE MOVING THROUGH THE REGION THIS MORNING.
SHOWERS ARE RANGING FROM MODERATE TO HEAVY IN INTENSITY WITH SHARP
DROPS IN VISIBILITY EXPECTED IF A MODERATE TO STRONG SHOWER PASSES
DIRECTLY OVER AN AIRPORT. SHOWER ACTIVITY IS EXPECTED TO DECREASE
THIS AFTERNOON BEFORE INCREASING AGAIN LATE THIS EVENING AS ANOTHER
ROUND OF RAIN RETURNS TONIGHT. EXPECTING CEILINGS TO LARGELY BE ON
THE VFR-MVFR BORDER BUT TEMPORARY DROPS LOWER ARE POSSIBLE DEPENDING
ON THE STRENGTH OF THE RAIN BAND. GUSTS PEAK BETWEEN 25-30 KNOTS
THIS MORNING BEFORE DECREASING THIS EVENING. NOT ANTICIPATING WINDS
TO BE AS GUSTY TONIGHT WITH THE NEXT BAND OF RAIN BUT CANNOT RULE
OUT THE POSSIBILITY OF LOCALLY HIGHER GUSTS OCCURRING.
VICINITY OF SFO...SCATTERED MODERATE INTENSITY SHOWERS ARE MOVING
THROUGH THE BAY AREA WITH THE POTENTIAL TO TEMPORARILY DROP
VISIBILITIES AND CEILING HEIGHTS. SHOWER ACTIVITY DIMINISHES THIS
AFTERNOON BEFORE INCREASING AGAIN THIS EVENING AS THE NEXT RAIN BAND
ARRIVES. GUSTS UP TO 30 KNOTS ARE EXPECTED THROUGH LATE THIS MORNING
BEFORE WINDS DECREASE THROUGH THE REMAINDER OF THE TAF PERIOD. NOT
ANTICIPATING GUSTS TO STRENGTHEN TONIGHT BUT CANNOT FULLY RULE OUT
THE POSSIBILITY OF GUSTS TO AROUND 20-25 KNOTS TONIGHT.
SFO BRIDGE APPROACH...SIMILAR TO SFO.
MONTEREY BAY TERMINALS...SCATTERED SHOWERS CONTINUE ALONG THE
MONTEREY PENINSULA THROUGH THIS EVENING. LIGHT RAIN RETURNS TONIGHT
AS THE NEXT RAIN BAND APPROACHES THE REGION. CEILINGS LOWER LATE
TONIGHT AS THE NEXT ROUND OF RAIN BEGINS WITH THE POTENTIAL FOR
VISIBILITIES TO DROP TO 4-5SM. GUSTS LOOK TO BE LOWER TONIGHT BUT
CANNOT RULE OUT THE OCCASIONAL STRONGER GUST AS THE RAIN BAND MOVES
IN.
MARINE
(TODAY THROUGH THURSDAY)
ISSUED AT 904 AM PST SAT JAN 3 2026
AN INCOMING STORM SYSTEM IS BRINGING SHOWERS AND A SLIGHT CHANCE
OF THUNDERSTORMS NOW THROUGH THE WEEKEND. GALE FORCE WINDS LINGER
OVER THE NORTHERN WATERS THROUGH TONIGHT WITH STRONG TO NEAR GALE
FORCE WINDS ACROSS THE REST OF THE COASTAL WATERS. OCCASIONAL GALE
FORCE GUSTS ARE POSSIBLE AS STRONGER SHOWERS REDEVELOP THIS
AFTERNOON AND EVENING. SEAS WILL BUILD TO 12 TO 16 FEET THIS
WEEKEND BEFORE ABATING EARLY NEXT WEEK.
BEACHES
ISSUED AT 1201 AM PST SAT JAN 3 2026
A COASTAL FLOOD WARNING IS IN EFFECT FOR THE SAN FRANCISCO BAY
THROUGH SATURDAY. A COASTAL FLOOD ADVISORY IS IN EFFECT FOR THE
PACIFIC COAST AND MONTEREY BAY THROUGH SUNDAY. PERIGEAN SPRING TIDES
(KING TIDES) WILL IMPACT THE REGION THROUGH SUNDAY. THIS IS DUE TO
THE COMBINATION OF THE FULL MOON ON 1/3, LUNAR PERIGEE ON 1/1, AND
PERIHELION ON 1/3. IN OTHER WORDS THE EARTH, SUN AND MOON ARE LINED
UP AND CLOSE TO EACH OTHER. IN ADDITION TO THE HIGH ASTRONOMICAL
TIDE, THE INCOMING LOW PRESSURE SYSTEM WILL BRING STRONG SOUTHERLY
WINDS, GENERATING SOME STORM SURGE, PARTICULARLY ON SATURDAY
MORNING. THE COMBINATION OF THESE FACTORS WILL BRING MODERATE
COASTAL FLOODING TO THE LOW-LYING AREAS NEAR SHORELINES AND TIDAL
WATERWAYS DURING HIGH TIDE THROUGH SUNDAY.
ON FRIDAY, THE SAN FRANCISCO TIDAL GAUGE RECORDED 2.26 FT OF
INUNDATION. LOOKING AHEAD, HIGH TIDE IS EXPECTED TO BE 2.5 FT
ABOVE NORMAL AT 10:26 AM SATURDAY AND 1.9 FT ABOVE NORMAL AT 11:18
AM SUNDAY. THESE PREDICTIONS INCLUDE UP TO 1.3 FEET OF STORM
SURGE THAT WILL ENHANCE THE ASTRONOMICAL TIDE AND FLOODING THREAT.
A REASONABLE WORSE CASE SCENARIO (10% EXCEEDANCE CHANCE) IS 2.7
FT OF INUNDATION ON SATURDAY. THE ALL TIME RECORD IS 2.8 FT FROM
1/27/1983. 2.5 FT HASN'T BEEN REACHED SINCE 1998. HIGH TIDE VARIES
UP TO 90 MINUTES EARLIER OR LATER ALONG THE PACIFIC COAST AND
THROUGH THE SAN FRANCISCO BAY, RESPECTIVELY.
A BEACH HAZARD STATEMENT IS IN EFFECT SUNDAY. LARGE SWELL WILL
IMPACT THE PACIFIC BEACHES, GENERATING LARGE BREAKING WAVES UP TO
20 FEET, STRONG RIP CURRENTS, AND SNEAKER WAVES. INEXPERIENCED
SWIMMERS SHOULD AVOID THE WATER. NOBODY SHOULD CLIMB THE COASTAL
ROCKS. NEVER TURN YOUR BACK ON THE OCEAN.
MTR WATCHES/WARNINGS/ADVISORIES
CA...COASTAL FLOOD WARNING UNTIL 2 PM PST THIS AFTERNOON FOR CAZ006-
506-508.
COASTAL FLOOD ADVISORY FROM 2 PM THIS AFTERNOON TO 2 PM PST
SUNDAY FOR CAZ006-506-508.
BEACH HAZARDS STATEMENT FROM SUNDAY MORNING THROUGH SUNDAY
EVENING FOR CAZ006-505-509-529-530.
COASTAL FLOOD ADVISORY UNTIL 2 PM PST SUNDAY FOR CAZ505-509-529-
530.
PZ...SMALL CRAFT ADVISORY UNTIL 9 AM PST SUNDAY FOR SF BAY N OF BAY
BRIDGE.
SMALL CRAFT ADVISORY UNTIL 3 PM PST SUNDAY FOR MRY BAY-PIGEON PT
TO PT PINOS 0-10 NM-PIGEON PT TO PT PINOS 10-60 NM-PT PINOS
TO PT PIEDRAS BLANCAS 0-10 NM-PT REYES TO PIGEON PT 0-10 NM.
GALE WARNING UNTIL 3 PM PST THIS AFTERNOON FOR PT ARENA TO PT
REYES 0-10 NM.
GALE WARNING UNTIL 9 PM PST THIS EVENING FOR PT ARENA TO PT
REYES 10-60 NM.
SHORT TERM...FLYNN
LONG TERM....FLYNN
AVIATION...KENNEDY
MARINE...KENNEDY
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