449
FXUS66 KMTR 020004
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
504 PM PDT WED APR 1 2026
..NEW AVIATION, MARINE
KEY MESSAGES
UPDATED AT 1214 PM PDT WED APR 1 2026
- UNSETTLED WEATHER TODAY AND TONIGHT WITH COOL, GUSTY, AND RAINY
CONDITIONS
- WARMING AND DRYING TREND KICKS OFF THURSDAY WITH WELL ABOVE
NORMAL TEMPERATURES AND MODERATE OFFSHORE FLOW INTO THE WEEKEND
SHORT TERM
ISSUED AT 1214 PM PDT WED APR 1 2026
(THIS EVENING THROUGH THURSDAY)
A GALE FORCE LOW PRESSURE SYSTEM OFF THE COAST OF THE
WASHINGTON/CANADA BORDER AND ITS ATTENDANT COLD FRONT WILL BE OUR
WEATHER MAKER THE NEXT 24 HOURS. AHEAD OF THE COLD FRONT,
SOUTHWESTERLY WINDS WILL INCREASE WITH GUSTS OF 20-30 MPH AND UP TO
40 MPH IN THE HIGHER TERRAIN. ISOLATED PRE-FRONTAL RAIN SHOWERS ARE
POSSIBLE WITH THE BEST CHANCES FOR RAIN HOLDING OFF UNTIL LATER THIS
AFTERNOON, SLOWLY SPREADING FROM NORTH TO SOUTH WITH THE COLD FRONT.
SO AS FAR AS A WET COMMUTE HOME GOES, THAT WILL LIKELY REMAIN
CONFINED TO THE NORTH BAY WITH THE SLOW PROGRESSION OF THE COLD
FRONT. THAT MEANS MOST OF THE RAINFALL SOUTH OF THE GOLDEN GATE
BRIDGE WILL FALL OVERNIGHT. RAINFALL TOTALS ON THE ORDER OF 0.10"-
0.25" ARE EXPECTED WITH LOCALLY HIGHER TOTALS IN THE HIGHER TERRAIN
OF THE NORTH BAY WITH THE HELP OF OROGRAPHIC LIFT AND LOCALLY LOWER
TOTALS IN THE INTERIOR CENTRAL COAST. EVEN WITH THE OVER PERFORMANCE
OF YESTERDAY'S RAINFALL, NO ADVERSE IMPACTS ARE EXPECTED WITH THE
EXCEPTION OF SLICK ROADWAYS. IT IS POSSIBLE THAT TODAY'S RAINFALL
OVER PERFORMS AS WELL DUE TO THE RECENCY BIAS OF THE WELL ABOVE
NORMAL TEMPERATURES AND DRY SPELL THAT HAS OCCURRED OVER THE LAST
FOUR WEEKS. THIS IS ACTUALLY A BEST CASE SCENARIO FOR BOTH WATER
STORAGE AND FIRE WEATHER CONCERNS. SIMILAR TO YESTERDAY, THE BEST
CHANCES FOR THUNDERSTORMS WILL REMAIN OFF TO OUR NORTH AND EAST WITH
OUR REGION BEING INSTABILITY LIMITED.
LONG TERM
ISSUED AT 1214 PM PDT WED APR 1 2026
(THURSDAY NIGHT THROUGH NEXT TUESDAY)
THE WARMING AND DRYING TREND WILL COMMENCE RIGHT BEHIND THE COLD
FRONT AS SURFACE HIGH PRESSURE NOSES IN FROM THE EASTERN PACIFIC
OCEAN. THIS WILL VEER WINDS TO BECOME NORTHWESTERLY WITH THE
TIGHTENED SURFACE PRESSURE GRADIENT YIELDING STRONG WINDS IN EXPOSED
AREAS LIKE THE HIGHER TERRAIN AND OVER THE WATERS. VERY DRY AIR WILL
GET FUNNELED IN BEHIND THE COLD FRONT WITH PWAT VALUES FORECAST TO
BE BETWEEN THE DAILY MINIMUM (0.18 INCHES) AND TENTH PERCENTILE
(0.34 INCHES) FOR 12Z TOMORROW. ECMWF AND GFS ENSEMBLES ARE IN
AGREEMENT THAT THE SFO-WMC PRESSURE GRADIENT WILL CHANGE FROM
POSITIVE (ONSHORE) TO NEGATIVE (OFFSHORE) TOMORROW NIGHT, BUT THAT'S
ABOUT WHERE THE AGREEMENT ENDS. THE UNCERTAINTY LIES IN HOW THE
AFOREMENTIONED HIGH BUILDS INTO THE INTERMOUNTAIN WEST AND HOW
STRONG IT GETS. THE ECMWF DETERMINISTIC AND ENSEMBLE CONTINUES TO
OFFER A STRONGER SOLUTION THAN ITS GFS COUNTERPARTS. BOTH MODELS AND
THEIR MEANS SHOW A RELATIVE MINIMUM OCCURRING AT 5 AM FRIDAY WITH
THE ECMWF ENSEMBLE MEAN AT -9.26 MB AND THE GEFS ENSEMBLE MEAN AT
-8.03 MB. 24 HOURS LATER AT 5 AM SATURDAY, THE ECMWF ENSEMBLE
MEAN BOTTOMS OUT AT -9.91 MB WHILE THE GEFS ENSEMBLE MEAN IS WELL
ON ITS WAY TO RELAXING AT -5.50 MB. NONETHELESS, CONFIDENCE IS
HIGH THAT A MODERATE OFFSHORE FLOW EVENT WILL TRANSPIRE THURSDAY
NIGHT WITH THE GRADIENT BEGINNING TO WEAKEN BY SUNDAY MORNING AND
RETURNING TO POSITIVE BY MONDAY. THIS WILL EQUATE TO GUSTS OF 40
TO 50 MPH IN THE NORTH BAY INTERIOR MOUNTAINS WITH GUSTS OF 30 TO
40 MPH IN THE EAST BAY HILLS, EASTERN SANTA CLARA HILLS, AND SANTA
CRUZ MOUNTAINS. WELL ABOVE NORMAL TEMPERATURES ARE EXPECTED OVER
THE WEEKEND WITH SATURDAY BEING THE WARMEST DAY OF THE WEEK.
CHANCES FOR RAIN MAY RETURN AS EARLY AS TUESDAY WITH THE HELP OF
AN UPPER-LEVEL TROUGH.
AVIATION
(00Z TAFS)
ISSUED AT 444 PM PDT WED APR 1 2026
BREEZY WEST-SOUTHWEST WINDS WILL PERSIST OUT AHEAD OF A COLD FRONT
THAT ARRIVES AROUND 04Z ACROSS THE NORTH BAY AND WILL BE THROUGH
THE MONTEREY BAY TERMINALS AROUND 10Z. THE MIX OF OF MVFR/VFR CIGS
WILL CONTINUE UNTIL AFTER THE FRONT IS THROUGH. THE AIRMASS
BEHIND THE FRONT IS VERY DRY WITH QUICK CLEARING EXPECTED TO VFR,
HOWEVER GUSTY WEST- NORTHWEST WINDS WILL PERSIST THROUGH MUCH OF
THE REMAINING TAF PERIOD IN THE POST-FRONTAL ENVIRONMENT.
VICINITY OF SFO...SIMILAR TO SFO.
SFO BRIDGE APPROACH...SCATTERED LIGHT RAIN THROUGH LATE TONIGHT
OUT AHEAD AND ALONG A FRONT THAT ARRIVES IN THE BAY AREA AROUND
07Z. EXPECT A MIX OF MVFR/VFR CIGS UNTIL THE FRONT IS THROUGH AND
QUICKLY BECOMES VFR WITH GUSTY WEST-NORTHWEST WINDS AROUND 09Z.
MONTEREY BAY TERMINALS...VFR CONDITIONS ARE EXPECTED UNTIL A COLD
FRONT ARRIVES AROUND 09Z WITH A DROP INTO MVFR CIGS UNTIL AROUND
12Z WITH SCATTERED LIGHT RAIN. VFR FOR THE REMAINDER OF THE DAY
ONCE THE FRONT MOVES THROUGH WITH BREEZY WEST-NORTHWEST WINDS.
MARINE
(TONIGHT THROUGH NEXT MONDAY)
ISSUED AT 444 PM PDT WED APR 1 2026
SOUTHWESTERLY BREEZES WILL INCREASE AHEAD OF THE COLD FRONT THIS
AFTERNOON AND VEER TO BECOME FRESH AND NORTHWESTERLY TONIGHT. THE
COLD FRONT WILL BRING LIGHT RAIN THIS AFTERNOON INTO TONIGHT.
WIDESPREAD HAZARDOUS CONDITIONS ARRIVE TOMORROW AND CONTINUE INTO
FRIDAY WITH STRONG NORTHERLY BREEZES AND ROUGH SEAS. NORTHERLY
BREEZES DIMINISH AND SEAS ABATE BY THIS WEEKEND.
MTR WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 3 AM PDT FRIDAY FOR PT ARENA TO PT
REYES 0-10 NM-PT ARENA TO PT REYES 10-60 NM-PT REYES TO
PIGEON PT 0-10 NM-SF BAY N OF BAY BRIDGE.
SMALL CRAFT ADVISORY FROM 3 AM THURSDAY TO 3 AM PDT FRIDAY 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.
SHORT TERM...SARMENT
LONG TERM....SARMENT
AVIATION...JM
MARINE...SARMENT
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