793
FXUS66 KMTR 071148
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
448 AM PDT TUE APR 7 2026
..NEW AVIATION, MARINE
KEY MESSAGES
UPDATED AT 1104 PM PDT MON APR 6 2026
- ABOVE NORMAL TEMPERATURES AND DRY CONDITIONS THROUGH WEDNESDAY
- UNSETTLED WEATHER RETURNS THURSDAY WITH BELOW NORMAL
TEMPERATURES AND BENEFICIAL RAINFALL
- ISOLATED TO SCATTERED THUNDERSTORMS THURSDAY AND FRIDAY
SHORT TERM
ISSUED AT 1104 PM PDT MON APR 6 2026
(TONIGHT THROUGH WEDNESDAY NIGHT)
UPPER-LEVEL SHORTWAVE RIDGING WILL DOMINATE OUR WEATHER THROUGH
WEDNESDAY. THIS WILL RESULT IN ABOVE NORMAL TEMPERATURES AND DRY
CONDITIONS. FORTUNATELY, A DECENT MARINE LAYER OF ABOUT 1,500 FEET
IS EXPECTED DURING THIS TIME WHICH WILL KEEP CONDITIONS COOLER AT
THE COAST AND THE NATURAL AIR CONDITIONING ON.
LONG TERM
ISSUED AT 1104 PM PDT MON APR 6 2026
(THURSDAY THROUGH NEXT MONDAY)
A VERTICALLY STACKED SURFACE LOW IN THE EASTERN PACIFIC OCEAN NEAR
37 N, -140 W WILL KICKOFF OUR PATTERN CHANGE. AS IT ENCROACHES OUR
MARINE ZONES ON THURSDAY, IT'LL INCREASE PWAT VALUES TO NEAR THE
90TH PERCENTILE (0.79 INCHES FOR 12Z APRIL 9TH). THE RRFS SOUNDING
PROFILE CAN BE CHARACTERIZED BY LOW CAPE, CONDITIONALLY UNSTABLE
LAPSE RATES, AND LOW SHEAR. AS SUCH, A SLIGHT (UP TO 15%) CHANCE FOR
THUNDERSTORMS IS BEING ADVERTISED FOR THURSDAY. THUNDERSTORM CHANCES
INCREASE FRIDAY (15%-25%) AS THE SURFACE LOW MOVES INLAND.
THUNDERSTORM IMPACTS INCLUDE LIGHTNING, LOCALLY HEAVY RAINFALL,
ERRATIC/GUSTY WINDS, AND SMALL HAIL. THERE STILL REMAINS UNCERTAINTY
IN THE EXACT LOCATION AND TIMING OF THE CUTOFF LOW AS THIS FEATURE
IS NOTORIOUSLY DIFFICULT TO FORECAST DUE TO THEIR INDEPENDENCE FROM
THE POLAR JET STREAM. AS SUCH, RAINFALL TOTALS ON THURSDAY AND
FRIDAY WILL BE HEAVILY DEPENDENT UPON WHERE RAIN
SHOWERS/THUNDERSTORMS DEVELOP. UPPER-LEVEL LONGWAVE TROUGHING
DEVELOPS OFF THE WEST COAST SATURDAY AS AN UPSTREAM TROUGH DIGS
SOUTH AND CONNECTS WITH THE CUTOFF LOW WITH THE HELP OF A DIP IN THE
POLAR JET STREAM. AS A RESULT, WIDESPREAD BENEFICIAL RAINFALL, BELOW
NORMAL TEMPERATURES, AND STRONG ONSHORE WINDS ARE EXPECTED SATURDAY
INTO SUNDAY WITH A COLD FRONTAL PASSAGE. GUSTS UP TO 40 MPH CAN BE
EXPECTED IN THE HIGHER TERRAIN AND THROUGH WEST-EAST ORIENTED GAPS
AND PASSES. WHEN ALL IS SAID AND DONE, RAINFALL ON THE ORDER OF
0.25"-0.75" INCHES IS EXPECTED WITH LOCALLY HIGHER TOTALS OF 1.00"-
1.50" INCHES IN THE COASTAL RANGES.
AVIATION
(12Z TAFS)
ISSUED AT 448 AM PDT TUE APR 7 2026
MARITIME AIR AND STRATUS CLOUDS /MVFR-IFR/ CONTINUE TO MOVE
INLAND SUPPORTED BY A PREDOMINANT PRESSURE GRADIENT 2.6 MB SFO-
SAC; A SURFACE RIDGE OF HIGH PRESSURE WAS LOCATED OVER THE CA
COASTAL AND OFFSHORE WATERS. THE MARINE LAYER DEPTH VARIES FROM
1500 TO 2000 FEET. ABOVE THE MARINE LAYER, LOWER TO MID LEVEL
THERMAL AND HEIGHT RIDGING (ABOVE EARLY APRIL NORMAL) PERSISTS.
HIGH RESOLUTION MODEL FORECASTS SHOW STRATUS MIXING OUT BY LATE
MORNING AND AFTERNOON WITH AREAS OF STRATUS RETURNING TONIGHT AND
WEDNESDAY MORNING.
VICINITY OF SFO...STRATUS /MVFR/ UNTIL 18Z MIXING OUT TO VFR FOR
THE AFTERNOON AND EVENING. WEST WIND NEAR 10 KNOTS INCREASING TO
15 TO 25 KNOTS FROM LATE MORNING THROUGH EARLY TO MID EVENING.
WEST WIND 5 TO 10 KNOTS TONIGHT AND WEDNESDAY MORNING.
SFO BRIDGE APPROACH...SIMILAR TO SFO.
MONTEREY BAY TERMINALS...STRATUS /MVFR-IFR/ UNTIL LATE MORNING
THEN MIXING OUT TO VFR FOR THE AFTERNOON AND EARLY EVENING. STRATUS
REDEVELOPS TONIGHT AND WEDNESDAY MORNING. ONSHORE WINDS 5 TO 12
KNOTS.
MARINE
(TODAY THROUGH SUNDAY)
ISSUED AT 426 AM PDT TUE APR 7 2026
SURFACE HIGH PRESSURE OFF THE CALIFORNIA COAST WILL RESULT IN
LIGHT TO MODERATE BREEZES ACROSS THE COASTAL WATERS TO WEDNESDAY
BEFORE DIMINISHING. LOW PRESSURE OVER THE EASTERN PACIFIC WILL
THEN BRING WET WEATHER INCLUDING A SLIGHT CHANCE OF THUNDERSTORMS
MID TO LATE WEEK. A SEPARATE LOW MAY ARRIVE FROM THE NORTHWEST AND
BRING ADDITIONAL WET WEATHER THIS WEEKEND.
MTR WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 9 PM PDT THIS EVENING FOR PT PINOS TO
PT PIEDRAS BLANCAS 0-10 NM.
SHORT TERM...SARMENT
LONG TERM....SARMENT
AVIATION...CANEPA
MARINE...CANEPA
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