200
FXUS66 KMTR 251852
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
1152 AM PDT MON MAY 25 2026
..NEW AVIATION, MARINE
KEY MESSAGES
UPDATED AT 135 AM PDT MON MAY 25 2026
- BELOW NORMAL TEMPERATURES WITH COASTAL AND HIGHER TERRAIN
DRIZZLE TODAY
- UPPER-LEVEL TROUGHING WILL BRING STRONG NORTHERLY WINDS TUESDAY
AND KICKOFF A GRADUAL WARMING AND DRYING TREND WEDNESDAY
SHORT TERM
ISSUED AT 135 AM PDT MON MAY 25 2026
(TODAY AND TONIGHT)
THE UNOFFICIAL START OF SUMMER SURE WON'T FEEL LIKE IT. TEMPERATURES
WILL REMAIN WELL BELOW NORMAL WITH THE HELP OF A 2,500 FEET DEEP
MARINE LAYER. STRATUS WILL RETREAT TO THE COAST BY LATE MORNING WITH
A MIX OF SUN AND CLOUDS EXPECTED FOR THE INTERIOR TOMORROW
AFTERNOON. SURFACE TROUGHING AND AN APPROACHING COLD FRONT WILL EVEN
ALLOW FOR SOME PRECIPITATION - THE COAST AND HIGHER TERRAIN WILL
HAVE THE GREATEST CHANCES WITH THE HELP OF OROGRAPHIC LIFT. IT'LL
LIKELY BE MORE IN THE WAY OF DRIZZLE THAN LIGHT RAIN; NONETHELESS, A
FEW HUNDREDTHS IS EXPECTED AT MOST.
LONG TERM
ISSUED AT 135 AM PDT MON MAY 25 2026
(TUESDAY THROUGH SUNDAY)
UPPER-LEVEL TROUGHING ARRIVES TOMORROW, MAKING IT THE COOLEST DAY OF
THE WEEK. OF MORE IMPACT WILL BE THE NORTHERLY (DRYING) WINDS. WIND
GUSTS OF 30-40 MPH ARE EXPECTED ALONG THE COAST, ACROSS RIDGELINES,
AND THROUGH GAPS AND PASSES. WIDESPREAD HAZARDOUS CONDITIONS FOR
SMALL CRAFT WILL RESULT. AS THE TROUGH DIGS INTO THE STATE
WEDNESDAY, IT IS EXPECTED TO BECOME A CUTOFF LOW THAT REMAINS NEAR-
STATIONARY THROUGH THURSDAY. THIS WILL SUPPORT A GRADUAL WARMING AND
DRYING TREND AS NORTHERLY WINDS REMAIN IN PLACE. OF MORE INTEREST
AND POTENTIAL IMPACT IS THE THUNDERSTORM THREAT. CHANCES ARE LOW
(10% OR LESS) WITH THE RELATIVELY BEST CHANCES FOR THE FAR INTERIOR.
THE THREE NECESSARY INGREDIENTS OF LIFT, INSTABILITY, AND MOISTURE
WILL BE PRESENT. CONDITIONALLY UNSTABLE LAPSE RATES (~7 DEGREES
C/KM) WILL YIELD LOW CAPE (~500 J/KG); WITH MOST OF IT PRESENTING AS
SURFACE BASED CAPE, SUFFICIENT DAYTIME HEATING WILL BE NEEDED. THE
LIMITING FACTOR WILL LIKELY BE MOISTURE WITH PWAT VALUES NEAR
AVERAGE. NEW WILDFIRE STARTS WILL BE A POTENTIAL HAZARD DUE TO FUELS
BEING ABOUT A MONTH AHEAD OF SCHEDULE. THE LOW IS EXPECTED TO FILL
AND BECOME AN OPEN WAVE BY FRIDAY, LEAVING THE AREA UNDER ZONAL FLOW
WITH ONSHORE FLOW OVER THE WEEKEND.
AVIATION
(18Z TAFS)
ISSUED AT 1152 AM PDT MON MAY 25 2026
SATELLITE SHOWS FAIRLY EXTENSIVE STRATUS /MVFR/ COVERAGE LATE
THIS MORNING. POOL OF STRATUS CORRESPONDS TO A POOL OF CHILLY
SURFACE TO LOWER LEVEL AIR MOVING IN FROM THE WEST. SLOW MIXING
OUT OF STRATUS IS OCCURING ON THE INLAND EDGES AND DO EXPECT SOME
ADDITIONAL MIXING TO OCCUR THROUGH PEAK DAYTIME HEATING TODAY. AT
THE 925 MB LEVEL (~ 2500 FEET) TEMPERATURES ARE CHILLY I.E. <
10TH PERCENTILE FOR LATE MAY LONG TERM OAKLAND UPPER AIR SOUNDING
CLIMATOLOGY. THE MARINE LAYER HAS DEEPENED AND WILL STAY STEADY
TONIGHT THEN DEEPEN MORE TUESDAY WITH THE ARRIVAL OF COOL AIR
ADVECTION UP THROUGH 850 MB LEVEL (~ 5000 FEET). ONSHORE WINDS
PREVAIL, SFO-SAC IS CURRENTLY 2.4 MB. PATCHY LIGHT DRIZZLE/RAIN IS
POSSIBLE DURING THE PERIOD. COLD FRONT FROM THE NORTHWEST BRINGS
REINFORCING CHILLY AIR MASS TONIGHT AND TUESDAY.
VICINITY OF SFO...STRATUS /MVFR-VFR/, ALONG WITH TEMPORARY CLEARING
POSSIBLE BY LATE AFTERNOON THOUGH IT'S LOW CONFIDENCE GIVEN CURRENT
PATTERN. THE 18Z TAF CARRIES STRATUS FOR THE TIME BEING. WEST WIND
UP TO 15 TO 25 KNOTS IN THE AFTERNOON AND EARLY EVENING. WEST WIND
BECOMING GUSTY TO 30 KNOTS, POSSIBLY HIGHER GUSTS POST COLD FRONT
TUESDAY AFTERNOON AND EVENING.
SFO BRIDGE APPROACH...SIMILAR TO SFO.
MONTEREY BAY TERMINALS...STRATUS /MVFR-VFR/ ALONG WITH TEMPORARY
CLEARING POSSIBLE IN THE AFTERNOON THOUGH WINDOW OF CLEARING IF IT
OCCURS WILL LIKELY BE LIMITED. WEST WINDS 10 TO 20 KNOTS DIMINISHING
TO 10 KNOTS TONIGHT AND TUESDAY MORNING. BREEZY TO GUSTY WEST TO
NORTHWEST WINDS POST COLD FRONT TUESDAY AFTERNOON AND EVENING.
MARINE
(TODAY THROUGH SATURDAY)
ISSUED AT 1130 AM PDT MON MAY 25 2026
LIGHT WEST TO NORTHWEST BREEZES TODAY BECOME MODERATE TO FRESH
NORTHWEST WINDS TONIGHT AND TUESDAY. NORTHWEST WINDS BECOMING
STRONG WITH GALE FORCE GUSTS EXPECTED FOR THE OUTER WATERS DURING
MID-WEEK. EXPECT BUILDING ROUGH SEAS TUESDAY AND WEDNESDAY, WHICH
LOOK TO LAST THROUGH THE WEEK.
MTR WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...SMALL CRAFT ADVISORY FROM 9 AM TO 9 PM PDT TUESDAY FOR MRY BAY-
PIGEON PT TO PT PINOS 0-10 NM-PIGEON PT TO PT PINOS 10-60
NM.
SMALL CRAFT ADVISORY FROM 3 AM TO 9 PM PDT TUESDAY FOR PT ARENA
TO PT REYES 0-10 NM-PT ARENA TO PT REYES 10-60 NM-PT PINOS
TO PT PIEDRAS BLANCAS 0-10 NM-PT REYES TO PIGEON PT 0-10 NM.
SHORT TERM...SARMENT
LONG TERM....SARMENT
AVIATION...CANEPA
MARINE...CANEPA
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