462
FXUS66 KMTR 271047
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
347 AM PDT FRI MAR 27 2026
..NEW CLIMATE
KEY MESSAGES
UPDATED AT 900 PM PDT THU MAR 26 2026
- ABOVE NORMAL TEMPERATURES PERSIST INTO THE WEEKEND
- OFFSHORE WINDS ACROSS THE NORTH BAY INTERIOR MOUNTAINS THRU
FRIDAY MORNING
- PATTERN CHANGE WITH CHANCES FOR LARGELY BENEFICIAL RAIN AND
INCREASED BREEZES NEXT WEEK
SHORT TERM
ISSUED AT 900 PM PDT THU MAR 26 2026
(TONIGHT THROUGH FRIDAY NIGHT)
ABOVE NORMAL WARMTH IS ANTICIPATED TO CONTINUE AS WE END THE
WORK-WEEK. THE CURRENT EXPECTATION IS THAT WE'LL SEE A MODEST PUSH
OF OFFSHORE BREEZES THROUGH THE PRE-DAWN HOURS ON FRIDAY. 925MB
FLOW OF 20 TO 30 KNOTS IS FORECAST TO EXTEND FROM THE NORTHERN
SACRAMENTO VALLEY SOUTHWARD THROUGH THE BAY AREA AND PORTIONS OF
THE CENTRAL COAST. THIS COULD TRANSLATE TO WIND GUSTS AT THE
HIGHEST ELEVATIONS OF THE NORTH BAY EXCEEDING 35-45 MPH THANKS TO
MOUNTAIN WAVE ACTIVITY THROUGH SUNRISE FRIDAY. IN ADDITION TO THE
COMPRESSIONAL WARMING ASSOCIATED WITH OFFSHORE WIND PATTERNS, THE
MARINE LAYER WILL REMAIN NEARLY NON-EXISTENT. WITH A DRY AIRMASS
IN PLACE, THERE SHOULD BE A LARGE DIURNAL TEMPERATURE RANGE WITH
MINT VALUES IN THE 40S (A FEW UPPER 30S CANNOT BE DISCOUNTED) WITH
FRIDAY AFTERNOON MAXTS IN THE 70S AND 80S, EVEN ACROSS COASTAL
REGIONS.
LONG TERM
ISSUED AT 900 PM PDT THU MAR 26 2026
(SATURDAY THROUGH NEXT THURSDAY)
THE WEEKEND WILL BE LARGELY PLEASANT WITH THE START OF OUR
COOLING TREND EXPECTED TO COMMENCE EARLY NEXT WEEK. HIGHS ON
SATURDAY AND SUNDAY ARE EXPECTED TO REMAIN ABOVE NORMAL,
ESPECIALLY FOR AREAS AWAY FROM THE COAST. THAT SAID, THERE ARE
SOME SIGNS THAT ONSHORE FLOW MAY BE A *SLIGHTLY* STRONGER ON
SATURDAY WHICH MAY EQUATE TO MAXTS A FEW DEGREES LOWER THAN
SUNDAY. IN FACT, HIGHER RESOLUTION NWP FROM PGE/SJSU WRF HINT THAT
A VERY SHALLOW AND COMPRESSED MARINE LAYER MAY TRY TO INVADE
COASTAL REGIONS (PACIFIC COAST AND SF/MONTEREY BAYS) ON SATURDAY
WITH POTENTIALLY SOME MORNING DRIZZLE/PATCHY FOG. WE'LL FINE TUNE
THIS IN FUTURE FORECASTS. BY SATURDAY AFTERNOON, HOWEVER, MOST OF
THE SHALLOW MOISTURE SHOULD BE SCOURED OUT WITH MOSTLY SUNNY SKIES.
DEPENDING ON THE BREADTH/INLAND EXTENT, THIS COULD MODULATE MAXTS
BY 2-5 DEGREES. STILL, IT'LL BE LARGELY PLEASANT ON SATURDAY.
OFFSHORE SURFACE TO 925MB FLOW APPEARS MORE ORGANIZED ON SUNDAY,
AND WHILE MORNING LOW CLOUDS/FOG CANNOT BE DISCOUNTED DURING THIS
TIME,ESPECIALLY ALONG THE COAST, SUNDAY FOR SURE LOOKS TO BE THE
WARMEST DAY THIS WEEKEND.
AFTER AN EXTENDED TIME OF ABOVE NORMAL WARMTH, THERE WILL BE A
VERY NOTICEABLE CHANGE AS UNSETTLED CONDITIONS TAKE SHAPE. THIS
WILL MEAN OPPORTUNITIES FOR RAINFALL AND INCREASED ONSHORE WINDS.
OUR STUBBORN AREA OF HIGH PRESSURE WILL BE DISLODGED EASTWARD BY
OUR LONGWAVE PATTERN THAT IS WELL-ADVERTISED BY A MAJORITY OF
DETERMINISTIC AND ENSEMBLE GUIDANCE. THERE ARE SOME DIFFERENCES
WITH RESPECT TO THE OVERALL AMPLITUDE/DEPTH OF THE UPPER TROUGH.
THAT SAID, THE GREATEST SPREAD IN THE NWP IS DUE TO DIFFERENCES IN
THE PROGRESSION OF VARIOUS UPPER TROUGHS. WHAT THIS TRANSLATES TO
IS HIGH CONFIDENCE THAT WE'LL SEE WIDESPREAD CLOUD COVER AND
RAINFALL WITH LOWER CONFIDENCE IN SPECIFIC ONSET/END TIMES.
A DISCERNIBLE PLUME OF PRECIPITABLE WATER (ABOVE 150% OF NORMAL
FOR THIS TIME OF YEAR) WILL STRETCH FROM THE CENTRAL PACIFIC
EASTWARD TOWARD THE WEST COAST BY THE TIME WE GET INTO MONDAY.
CONFIDENCE IS INCREASING THAT A BULK OF THE MORE WIDESPREAD
ACTIVITY WILL BE LATER MONDAY AND INTO TUESDAY AS A RIBBON OF
50-70 KNOT MID-LEVEL FLOW DEVELOPS AHEAD OF A POSITIVELY TITLED
UPPER TROUGH. THIS CORRIDOR OF GREATER WINDS HAS SHIFTED A BIT
FARTHER SOUTH COMPARED TO WHAT WAS FORECAST YESTERDAY BY NWP. NOT
SURPRISINGLY, THE RICHEST PLUME OF MOISTURE APPEARS THAT IT'S
AIMED A BIT MORE AT THE CENTRAL COAST COMPARED TO AREAS NORTH OF
THE GOLDEN GATE. IN FACT, THE LATEST QPF THROUGH THURSDAY EVENING
HAS INCREASED ACROSS THE SANTA LUCIA RANGE/BIG SUR COASTLINE WHILE
TICKING DOWN SLIGHTLY ACROSS THE WESTERN SONOMA HILLS. THIS
ALIGNS WELL WITH BOTH GEFS AND EPS PROBABILITY OF INTEGRATED VAPOR
TRANSPORT ABOVE 250 KILOGRAM/METER/SECOND MAXIMIZED SOUTH OF THE
GOLDEN GATE (AND PROBABLY SOUTH OF MONTEREY BAY), AT LEAST WITH
THIS INITIAL UPPER TROUGH ON TUESDAY.
A SECOND, MORE COMPACT UPPER TROUGH WILL SWING THROUGH THE REGION
EARLY WEDNESDAY. THIS SECOND OPPORTUNITY FOR PRECIPITATION WILL
BE WHAT ALLOWS TOTALS TO TICK UP A LITTLE HIGHER ACROSS THE NORTH
BAY. IN TOTAL, RAIN AMOUNTS ACROSS THE COASTAL RANGES IN SONOMA
COUNTY STILL HAVE THE BEST CHANCE OF ECLIPSING 1" (AROUND A 40%
CHANCE), WITH THE PROBABILITY OF 1" LOWER FARTHER SOUTH. OF
COURSE, AREAS SUCH AS THE SANTA CRUZ MOUNTAINS AND SANTA LUCIA
RANGE ARE LIKELY TO BE THE SPOTS WHERE RAIN TOTALS COULD RIVAL
REGIONS FARTHER NORTH. INSTABILITY DOES BUILD A LITTLE BIT MORE
WITH THIS SECOND SYSTEM. WHILE THE PROBABILITY OF THUNDER REMAINS
AROUND 10%, THE CONVECTIVE NATURE OF ACTIVITY DOES COMPLICATE RAIN
AMOUNTS SOME DUE TO THE ISOLATED TO SCATTERED NATURE OF PRECIP.
IT DOES APPEAR THAT RIDGING WILL RETURN SOMETIME THURSDAY AND
INTO FRIDAY, BUT TIMING OF WHEN THIS TROUGH WILL PROGRESS EASTWARD
IS HIGHLY UNCERTAIN. TOTAL RAIN AMOUNTS ARE FORECAST TO AVERAGE
BETWEEN ONE TENTH OF AN INCH ACROSS INLAND AREAS (INCLUDING THE
POPULATION CENTERS) TO HALF AN INCH ACROSS COASTAL REGIONS OF THE
CENTRAL COAST AND PORTIONS OF THE NORTH BAY. AS NOTED ABOVE,
WESTERN SONOMA COUNTY WILL HAVE THE BEST CHANCE FOR RAIN AMOUNTS
AT OR ABOVE 1 INCH. IT SHOULD BE RESTATED THAT IF THIS SECOND
SYSTEM AMPLIFIES MORE THAN CURRENTLY ANTICIPATED, THEN THE WINDOW
FOR RAINFALL COULD BE EXTENDED INTO FRIDAY WHICH COULD DRIVE
TOTALS UPWARD. STILL, RAIN AMOUNTS APPEAR LARGELY BENEFICIAL AS
EVEN THE 90TH PERCENTILE QPF (REASONABLE-WORST CASE SCENARIO) ARE
LARGELY 1-2" ACROSS THE REGION WHICH SHOULDN'T TRANSLATE TO A
MAJOR FLOOD RISK GIVEN THE RECENT DRY SPELL.
THIS SECOND SYSTEM WILL HAVE THE POTENTIAL TO PRODUCE THE
STRONGER NON-CONVECTIVE WINDS (LARGELY ACROSS THE HIGHER TERRAIN)
AS THE BREADTH OF HIGHER MOMENTUM RESIDES THROUGH THE COLUMN.
PROBABILITY OF 40 MPH WINDS ARE AROUND 60-80% ACROSS THE NORTH BAY
MOUNTAINS, EAST BAY HILLS, SONOMA COASTAL AND GABILAN RANGE(S).
RIDGING IS EXPECTED TO RETURN TOWARD THE END OF NEXT WEEK. AT THE
SURFACE A COLD FRONT WILL SLIDE SOUTHWARD AND DRY OUT THE LOW
LEVELS. AS SURFACE PRESSURES RISE ACROSS THE GREAT BASIN, WE MAY
FIND OURSELVES IN ANOTHER PERIOD WITH MODEST OFFSHORE WINDS. WE'LL
EXAMINE THIS A LITTLE CLOSER WITH TIME.
AVIATION
(06Z TAFS)
ISSUED AT 948 PM PDT THU MAR 26 2026
VFR WITH WIDESPREAD HIGH CLOUDS ACROSS THE REGION. WINDS ARE
GRADUALLY DIMINISHING IN A GENERALLY ONSHORE PATTERN, EXCEPT IN THE
HIGHER ELEVATIONS, PARTICULARLY IN THE NORTH BAY, WHERE BREEZY
OFFSHORE WINDS PERSIST. LIGHT WINDS DEVELOP OVERNIGHT, ALONG WITH
LLWS CONCERNS IN THE INTERIOR NORTH AND EAST BAYS AS THE WINDS ALOFT
REMAIN STRONG. WIDESPREAD ONSHORE FLOW RESUMES FRIDAY AFTERNOON.
HIGH RESOLUTION MODELS DEPICT THE RETURN OF MARINE LAYER STRATUS
FRIDAY NIGHT INTO SATURDAY MORNING, ALTHOUGH THE GREATEST CONFIDENCE
FOR IMPACTS, ESPECIALLY FOR LOCATIONS AWAY FROM THE IMMEDIATE COAST,
COMES AFTER THE END OF THE 24-HOUR TAF PERIOD.
VICINITY OF SFO... VFR WITH THIN HIGH CLOUDS THROUGH THE TAF PERIOD.
BREEZY WEST-NORTHWEST WINDS PERSIST THROUGH THE EVENING HOURS. WINDS
GRADUALLY DIMINISH IN THE LATE EVENING WITH LIGHT WINDS FRIDAY
MORNING, BEFORE THE BREEZY WEST-NORTHWEST WINDS RESUME DURING THE
AFTERNOON. BEYOND THE TAF PERIOD, MONITORING THE POTENTIAL FOR
STRATUS IMPACTS AT THE TERMINAL EARLY SATURDAY MORNING, ALTHOUGH
CONFIDENCE IS VERY LOW.
SFO BRIDGE APPROACH... SIMILAR TO SFO.
MONTEREY BAY TERMINALS... MODERATE TO HIGH CONFIDENCE OF VFR
THROUGHOUT THE TAF PERIOD. LIGHT DRAINAGE WINDS OVERNIGHT BEFORE
BREEZY NORTHWEST WINDS RESUME FRIDAY AFTERNOON. MARINE LAYER STRATUS
EXPECTED TO DEVELOP FRIDAY NIGHT, BUT THE GREATEST CONFIDENCE FOR
IMPACTS TO THE TERMINALS COMES AFTER THE END OF THE TAF PERIOD ON
SATURDAY MORNING.
MARINE
(TONIGHT THROUGH NEXT WEDNESDAY)
ISSUED AT 948 PM PDT THU MAR 26 2026
FRESH TO STRONG GUSTS CONTINUE THROUGH THE FAR OUTER WATERS
OVERNIGHT, DIMINISHING ON FRIDAY BEFORE STRONG GUSTS RETURN TO THE
NORTHERN OUTER WATERS FRIDAY NIGHT. ROUGH SEAS WILL BEGIN TO
SUBSIDE INTO FRIDAY, BECOMING MODERATE BY THE WEEKEND. RELATIVELY
LIGHT ONSHORE WINDS DEVELOP FRIDAY INTO THE WEEKEND WITH LIGHT
RAIN RETURNING BY THE MIDDLE OF NEXT WEEK.
CLIMATE
ISSUED AT 301 AM PDT FRI MAR 27 2026
HERE ARE THE RECORD HIGH TEMPERATURES AT THE LONG TERM SITES FOR
MARCH 27TH AND MARCH 29TH.
LOCATION MARCH 27TH MARCH 29TH
SANTA ROSA 87 IN 1930 86 IN 2018
SAN RAFAEL 82 IN 1969, 1951 85 IN 2018
KENTFIELD 90 IN 1923 84 IN 1935
NAPA 86 IN 1930 83 IN 2018, 1968
RICHMOND 82 IN 1952 79 IN 1968
LIVERMORE 82 IN 1969, 1930 85 IN 2015
SAN FRANCISCO 84 IN 1923 81 IN 2018
SFO AIRPORT 77 IN 2021, 1986 81 IN 2018
REDWOOD CITY 83 IN 1969 85 IN 2018, 1968
HALF MOON BAY 76 IN 1952 77 IN 2004
OAKLAND 79 IN 1986 79 IN 2003
SAN JOSE 85 IN 1923 82 IN 2018
SALINAS AIRPORT 80 IN 1969, 1952 86 IN 2018
MTR WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...NONE.
SHORT TERM...BAIN
LONG TERM....BAIN
AVIATION...DIALH
MARINE...DIALH
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