541
FXUS66 KMTR 271807
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
1007 AM PST TUE JAN 27 2026
..NEW AVIATION
KEY MESSAGES
UPDATED AT 319 AM PST TUE JAN 27 2026
- MILD WITH INCREASING CLOUD COVER THROUGH THE DAY
- INCREASING RAIN CHANCES TONIGHT THROUGH WEDNESDAY MORNING FOR
THE NORTH BAY INTO BAY AREA, WITH LIGHT AMOUNTS BETWEEN
0.1"-0.2" EXPECTED WHERE IT DOES RAIN
- DRIER CONDITIONS AND WEAK OFFSHORE FLOW RETURN QUICKLY BY
WEDNESDAY AFTERNOON
- BEACH HAZARDS STATEMENT FOR INCREASED RISK OF SNEAKER WAVES
AND RIPTIDES WEDNESDAY NIGHT THROUGH FRIDAY MORNING
UPDATE
ISSUED AT 850 AM PST TUE JAN 27 2026
IT WAS A CHILLY MORNING ACROSS THE INTERIOR VALLEYS WHERE
TEMPERATURES DROPPED INTO THE MID TO UPPER 30S. PORTIONS OF FAR
INTERIOR MONTEREY COUNTY (VICINITY OF FORT HUNTER LIGGETT) DROPPED
BELOW FREEZING OVERNIGHT. TEMPERATURES ARE WARMING UP WITH FOG
CURRENTLY BEING REPORTED AT THE LIVERMORE AIRPORT. LIGHT RAIN
REMAINS ON TRACK TO RETURN TO THE NORTH BAY THIS EVENING INTO THE
OVERNIGHT HOURS. PRECIPITATION TOTALS REMAIN LIGHT WITH BETWEEN 0.25-
0.50" IN THE NORTH BAY AND UP TO 0.10" ACROSS SAN FRANCISCO AND
PORTIONS OF THE EAST BAY/SAN MATEO COUNTY. NO IMPACTS ARE EXPECTED
FROM THIS DUE TO THE SUBSTANTIAL DRY SPELL IN BETWEEN OUR LAST
SYSTEM AND THIS CURRENT ONE.
SHORT TERM
ISSUED AT 319 AM PST TUE JAN 27 2026
(TODAY AND TONIGHT)
THE 00Z KOAK SOUNDING RECORDED 0.43" PWAT LAST NIGHT WITH HIRES
SHORT-TERM SOUNDINGS INDICATING SIMILAR OR LOWER VALUES UNTIL AFTER
SUNRISE THIS MORNING IN THE NORTH BAY, WITH THE BOUNDARY LAYER NOT
BEGINNING TO SATURATE UNTIL LATER THIS MORNING INTO THE AFTERNOON
THAT FAR NORTH. PREFRONTAL DRIZZLE OR LIGHT RAIN IS POSSIBLE ALONG
THE NORTH BAY COASTAL RANGES LATER THIS MORNING INTO THE AFTERNOON
WITH THE ADDED LIFT. OTHERWISE, THE BULK OF THE RAINFALL IS EXPECTED
TO MOVE INLAND AFTER SUNSET TONIGHT, AND SHIFT EAST BY SUNRISE
WEDNESDAY MORNING. SLIGHT CHANCE POPS EXTEND AS FAR SOUTH AS THE
SANTA CRUZ MOUNTAINS LATER TODAY AND TONIGHT, HOWEVER RAIN TOTALS
SOUTH OF THE NORTH BAY ARE EXPECTED TO BE LESS THAN 0.1" WHERE IT
DOES RAIN. INLAND AREAS OF THE NORTH BAY LIKE SANTA ROSA ARE LIKELY
TO SEE AROUND 0.20" (MEAN HI-RES ENSEMBLE %) WITH HIGHER END
REASONABLE AMOUNTS NEAR 0.30" (HI-RES 75TH%), THUS LITTLE IMPACTS
BEYOND WETTING RAINFALL ARE EXPECTED. LESSER AMOUNTS ARE EXPECTED
FARTHER EAST AS THE PROGRESSIVE SHORTWAVE TROUGH MOVES OUT OF OUR
AREA TO THE EAST.
LONG TERM
ISSUED AT 319 AM PST TUE JAN 27 2026
(WEDNESDAY THROUGH MONDAY)
THE PROGRESSIVE UPPER LEVEL TROUGH MOVING ACROSS THE NORTH BAY WILL
SHIFT EAST WEDNESDAY MORNING WITH A RIDGING PATTERN DEVELOPING
QUICKLY IN ITS WAKE. WEAK OFFSHORE FLOW WILL RETURN AS A RESULT WITH
ANOTHER DRY AIRMASS FILLING IN FOR THE REMAINDER OF THE WORK WEEK
INTO THE BEGINNING OF WEEKEND. LONG PERIOD WESTERLY SWELL AND
INCREASING WAVE HEIGHTS WILL RESULT IN AN INCREASED RISK OF SNEAKER
WAVES AND RIPTIDES ALONG WITH BREAKING WAVES UP TO 19FT WEDNESDAY
NIGHT THROUGH FRIDAY MORNING, WITH A BEACH HAZARDS STATEMENT ISSUED
FOR THAT TIME PERIOD, SEE THE BEACH HAZARDS DISCUSSION FOR MORE
DETAILS. SLIGHT CHANCE POPS RETURN AS SOON AS LATE SATURDAY NIGHT
INTO SUNDAY FOR THE NORTH BAY ONCE AGAIN, HOWEVER A LACK IN
CONSENSUS OF THE LOCATION, DEPTH AND TIMING OF THE DEVELOPING TROUGH
LEAVES FAR MORE QUESTIONS THAN ANSWERS AT THIS POINT.
AVIATION
(18Z TAFS)
ISSUED AT 1006 AM PST TUE JAN 27 2026
MOSTLY VFR CONDITIONS ACROSS THE REGION AT THIS HOUR. AS A WEAK
FRONTAL BOUNDARY APPROACHES THE REGION LOOK FOR CONDITIONS TO
DETERIORATE AROUND MID AFTERNOON ACROSS THE NORTH BAY AND THEN
LATE THIS EVENING AND OVERNIGHT ACROSS THE BAY AREA TERMINALS. AT
THIS TIME, MOSTLY MVFR CONDITIONS ARE EXPECTED OVER THIS REGION
WITH FOG RETURNING EARLY WEDNESDAY MORNING AT STS AND LVK. LOOKING
LESS LIKELY MRY AND SNS WILL RECEIVE ANYTHING MORE THAN VCSH AND
BRIEF MVFR CONDITIONS THIS EVENING AND INTO EARLY WEDNESDAY
MORNING. VFR CONDITIONS ARE EXPECTED BY WEDNESDAY AFTERNOON IN
WAKE OF THE FRONTAL PASSAGE.
VICINITY OF SFO...VFR CONDITIONS WILL PREVAIL THROUGH AROUND 03Z
WEDNESDAY WHEN CONDITIONS BECOME MORE LIKELY TO REDUCE TO MVFR AS
RAIN SHOWERS MOVE ACROSS THE REGION. A GREATER PROBABILITY WILL BE
IN THE 06-09Z WEDNESDAY TIMEFRAME FOR MVFR (TEMPORARY IFR IF AND
WHEN RA IS PRESENT) AS THE MAIN RAIN BAND IS FORECAST TO MOVE
ACROSS THE TERMINALS. MVFR WILL PERSIST THROUGH ABOUT 18Z
WEDNESDAY BEFORE IMPROVING TO VFR AS SKIES CLEAR IN WAKE OF THE
PASSING FRONTAL BOUNDARY.
SFO BRIDGE APPROACH...SIMILAR TO SFO.
MONTEREY BAY TERMINALS...MOSTLY VFR THROUGH THE TAF PERIOD.
DRAINAGE WINDS (SOUTHEASTERLY) ONCE AGAIN AT SNS WILL BECOME
ONSHORE BY THIS AFTERNOON. A WEAKENING FRONTAL BOUNDARY WILL
APPROACH LATE THIS EVENING INCREASING THE PROBABILITY FOR MVFR
CONDITIONS. HOWEVER, CONFIDENCE IS ONLY MODERATE AT THIS TIME.
THERE IS GREATER PROBABILITY FOR VFR CONDITIONS BY 18Z WEDNESDAY.
MARINE
(TODAY THROUGH SUNDAY)
ISSUED AT 850 AM PST TUE JAN 27 2026
LIGHT TO MODERATE SOUTHERLY FLOW WILL PREVAIL OVER MOST OF THE
WATERS AS A WEAK COLD FRONT APPROACHES FROM THE WEST TODAY THROUGH
EARLY WEDNESDAY MORNING. THIS WILL BRING LIGHT RAIN TO THE
NORTHERN COASTAL WATERS THROUGH WEDNESDAY MORNING. WINDS WILL BE
MODERATE TO BREEZY NORTH OF POINT REYES WITH LOCALLY HAZARDOUS
CONDITIONS FOR SMALL CRAFT. WINDS DIMINISH ON WEDNESDAY AND SWITCH
TO NORTHERLY THAT NIGHT. MODERATE SEAS WILL PREVAIL THROUGH
TUESDAY, BUT BUILD ROUGH TO VERY ROUGH WEDNESDAY NIGHT.
BEACHES
ISSUED AT 359 AM PST TUE JAN 27 2026
LONG PERIOD SWELLS WITH LOW WAVE HEIGHTS BEGIN TO ARRIVE ON
WEDNESDAY, BUT WAVE HEIGHTS BEGIN TO INCREASE THAT NIGHT WHILE
PERIODS STAY LONG LEADING TO HAZARDOUS CONDITIONS. A BEACH
HAZARDS STATEMENT HAS BEEN ISSUED FROM 09 PM WEDNESDAY THROUGH 09
AM FRIDAY. SIGNIFICANT WAVE HEIGHTS LOOK TO RANGE FROM 14 TO 19
FEET. THE MAIN THREAT WILL BE FROM SNEAKER WAVES AND RIP CURRENTS.
STAY OFF OF JETTIES, PIERS, ROCKS, AND OTHER WATERSIDE
INFRASTRUCTURE. REMAIN OUT OF THE WATER TO AVOID HAZARDOUS SURF
AND NEVER TURN YOUR BACK ON THE OCEAN.
MTR WATCHES/WARNINGS/ADVISORIES
CA...BEACH HAZARDS STATEMENT FROM WEDNESDAY EVENING THROUGH FRIDAY
MORNING FOR CAZ006-505-509-529-530.
PZ...SMALL CRAFT ADVISORY UNTIL 9 PM PST THIS EVENING FOR PT ARENA TO
PT REYES 0-10 NM-PT ARENA TO PT REYES 10-60 NM.
SMALL CRAFT ADVISORY FROM 9 AM THURSDAY TO 3 AM PST FRIDAY FOR
PIGEON PT TO PT PINOS 10-60 NM-PT ARENA TO PT REYES 0-10 NM.
SMALL CRAFT ADVISORY FROM 3 AM THURSDAY TO 3 AM PST FRIDAY FOR
PT ARENA TO PT REYES 10-60 NM.
SHORT TERM...JM
LONG TERM....JM
AVIATION...RGASS
MARINE...RGASS
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