043
FXUS66 KMTR 280453
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
953 PM PDT FRI MAR 27 2026
..NEW AVIATION, MARINE
KEY MESSAGES
UPDATED AT 1010 AM PDT FRI MAR 27 2026
- ABOVE NORMAL TEMPERATURES CONTINUE THROUGH THE WEEKEND
- BENEFICIAL RAIN POSSIBLE NEXT WEEK
SHORT TERM
ISSUED AT 1010 AM PDT FRI MAR 27 2026
(THIS AFTERNOON THROUGH SATURDAY)
DESPITE THE HIGH CLOUDS MOVING IN FROM THE SOUTH, MAX
TEMPERATURES TODAY WILL CHALLENGE DAILY RECORDS. THE MORNING
SOUNDING FOUND 850 MB TEMPERATURES OF 16.75 C, AND A 500 MB HEIGHT
OF 5800M. THOSE BENCHMARKS ARE BOTH BETWEEN THE 90TH PERCENTILE
AND DAILY MAX FOR THIS DATE. IN ADDITION TO THE BACKGROUND
ATMOSPHERIC HEAT CONTENT, THERE ARE OFFSHORE WINDS HELPING KEEP
THE SURFACE WARM AND DRY VIA DOWNSLOPE FLOW AND ADIABATIC HEATING.
AS SUCH, A COUPLE DAILY RECORDS MAY FALL TODAY, BUT NOT NEARLY AS
WIDESPREAD OR HISTORIC AS LAST WEEK WHEN THE 850 MB TEMPERATE
REACHED A RIDICULOUS 22 C. DESPITE THE POSSIBLE RECORDS, THE HIGH
CLOUDS AND GENTLE BREEZE SHOULD HELP IT FEEL PLEASANT FOR MOST
THIS AFTERNOON.
BY SATURDAY THE SURFACE HIGH PRESSURE OVER THE ROCKIES WILL BE
REPLACED BY LOW PRESSURE MOVING IN FROM CANADA. THIS WILL EITHER
NEUTRALIZE THE OFFSHORE GRADIENT OR FLIP IT TO WEAK ONSHORE FLOW,
DEPENDING ON THE STRENGTH OF THE LOW PRESSURE. THIS CHANGE OPENS
THE DOOR FOR A SHALLOW MARINE LAYER TO CREEP IN, BRINGING LOW
CLOUDS AND POSSIBLY MORNING FOG TO THE COAST AND ADJACENT LOW-
LYING AREAS. THE ONSHORE WINDS WILL ALSO SUPPRESS THE
TEMPERATURES A BIT, BUT THE WARM LOW-MIDDLE ATMOSPHERE WILL ENSURE
TEMPERATURES STAY WELL ABOVE NORMAL.
LONG TERM
ISSUED AT 1010 AM PDT FRI MAR 27 2026
(SATURDAY NIGHT THROUGH NEXT THURSDAY)
AFTER A MINOR COOL-DOWN SATURDAY, NEAR RECORD WARMTH RETURNS ON
SUNDAY. SOME LIGHT OFFSHORE FLOW IS LIKELY TO RETURN, BUT THE
HIGH CLOUDS THAT ARE SUPPRESSING TEMPERATURES TODAY WILL BE
THINNER AND MORE SCATTERED. INLAND AREAS SHOULD REACH THE MID 80S,
WITH 70S ALONG THE COAST. MONDAY IS A TRANSITION DAY BEFORE
TEMPERATURES FINALLY RETURN TO NORMAL NEXT WEEK. ENSEMBLE
CLUSTERS AGREE THAT A TROUGH WILL MOVE IN AND USHER OUT THE
PERSISTENT RIDGE. THE DEPTH OF THIS TROUGH IS STILL IN QUESTION,
WITH SOME SOLUTIONS KEEPING THE MAJORITY OF THE PRECIPITATION IN
THE PACIFIC NORTHWEST AND OTHERS DIGGING DOWN TO CENTRAL
CALIFORNIA. SO WE KNOW THE TEMPERATURES WILL DROP, BUT THE
PRECIPITATION AMOUNT REMAINS IN QUESTION. OUR OFFICIAL FORECAST
HAS AROUND 1/4" IN THE INTERIOR AND UP TO 1" IN THE COASTAL
MOUNTAINS FROM TUESDAY THROUGH WEDNESDAY. THE DRY SCENARIO IS MORE
LIKE A TRACE IN THE LOW LANDS AND A FEW HUNDREDTHS IN THE COASTAL
MOUNTAINS, WHILE THE WET SCENARIO IS MORE LIKE 3/4" INLAND AND
2-3 INCHES IN THE COASTAL MOUNTAINS. THE REALITY CAN BE EITHER OF
THESE, OR OF COURSE SOMEWHERE IN THE MIDDLE. THERE IS EVEN A 20%
CHANCE THAT WE FALL OUTSIDE OF THAT WIDE RANGE, TO ONE SIDE OR THE
OTHER. THIS JUST HIGHLIGHTS THE REMAINING UNCERTAINTY WITH THIS
SYSTEM. DON'T BANK ON ANY DETERMINISTIC FORECAST JUST YET.
WHATEVER HAPPENS MID WEEK, IT DOES LOOK LIKE THE PATTERN WILL
STABILIZE LATE WEEK BEFORE ANOTHER RIDGE BUILDS IN THE FOLLOWING
WEEK.
AVIATION
(06Z TAFS)
ISSUED AT 952 PM PDT FRI MAR 27 2026
VFR WITH HIGH CLOUDS ACROSS THE REGION. ONSHORE WINDS ARE
DIMINISHING ACROSS THE REGION AND WILL BECOME LIGHT OVERNIGHT.
STRATUS AND FOG ARE BEGINNING TO CRAWL UP THE BIG SUR COAST. MAIN
FORECAST ISSUE TONIGHT IS THE PROGRESSION AND EXTENT OF THIS STRATUS
THROUGH EARLY SATURDAY MORNING. CURRENT THINKING IS FOR THE STRATUS
TO COME TO THE IMMEDIATE COASTAL TERMINALS AROUND 09-10Z, WITH
INTRUSIONS INTO THE SONOMA COUNTY VALLEYS, THE BERKELEY AREA, AND
THE MONTEREY BAY REGION THROUGH THE MORNING. MODERATE CONFIDENCE FOR
FOG DEVELOPMENT AT STS, HAF, MRY, AND SNS THROUGH THE MORNING.
STRATUS RETREATS AND LIFTS THROUGH SATURDAY MORNING, WITH PATCHY
STRATUS PERSISTING AT THE IMMEDIATE COAST WHILE THE GENTLE ONSHORE
WINDS RESUME IN THE AFTERNOON.
VICINITY OF SFO... VFR WITH THIN HIGH CLOUDS THROUGH THE TAF PERIOD.
BREEZY WEST-NORTHWEST WINDS CONTINUE THROUGH THE EVENING HOURS.
WINDS GRADUALLY DIMINISH IN THE LATE EVENING WITH LIGHT WINDS
SATURDAY MORNING, BEFORE THE BREEZY WEST-NORTHWEST WINDS RESUME
DURING THE AFTERNOON. VERY LOW CONFIDENCE OF STRATUS IMPACTS TONIGHT
AT THE TERMINAL, WITH MODERATE CONFIDENCE OF IMPACTS TO THE BERKELEY
AREA AND LOWER CONFIDENCE AT OAK. CONFIDENCE IS SLIGHTLY HIGHER FOR
STRATUS IMPACTS SATURDAY NIGHT INTO SUNDAY MORNING, BUT THE OVERALL
LEVEL OF CONFIDENCE REMAINS LOW.
SFO BRIDGE APPROACH... SIMILAR TO SFO.
MONTEREY BAY TERMINALS... VFR CONDITIONS AT PRESENT, LIGHT WINDS
THROUGH THE NIGHT. MODERATE TO HIGH CONFIDENCE THAT A SURGE OF
STRATUS WILL IMPACT THE REGION BEGINNING AROUND 09-10Z WITH PATCHY
FOG LIKELY. SATURDAY MORNING, CEILINGS LIFT AND LATER DISSIPATE AS
BREEZY NORTHWEST WINDS RESUME, WITH A POTENTIAL EARLY RETURN OF
STRATUS AROUND 03Z FOR MRY.
MARINE
(TONIGHT THROUGH NEXT THURSDAY)
ISSUED AT 952 PM PDT FRI MAR 27 2026
HIGH PRESSURE OVER THE EASTERN PACIFIC PERSISTS THROUGH THE
WEEKEND, GENERATING A MODERATE TO FRESH NW BREEZE AND MODERATE
SEAS. CONDITIONS WILL BE SLIGHTLY HEAVIER ON SATURDAY ACROSS THE
NW WATERS, WITH A FRESH TO STRONG NW BREEZE AND ROUGH SEAS TO 8
FT. AN INCOMING TROUGH WILL SHIFT WINDS TO THE WEST AND SOUTHWEST
TOWARDS THE MIDDLE OF NEXT WEEK.
FIRE WEATHER
ISSUED AT 1010 AM PDT FRI MAR 27 2026
IN ADDITION TO THE HEAT, THE AIR IS ALSO DRY THANKS TO SOME
OFFSHORE WINDS SUPPORTED BY THE GRADIENT BETWEEN HIGH PRESSURE
OVER THE ROCKIES AND A THERMAL TROUGH OVER THE COAST. THE SFO-WMC
GRADIENT HAS BEEN AROUND -10 MB FOR THE LAST 12 HOURS. WINDS WERE
GUSTING TO 30-45 MPH ACROSS HIGHER ELEVATIONS OF THE NORTH AND
EAST BAY, ENHANCED BY SOME MOUNTAIN WAVE ACTIVITY. THE RELATIVE
HUMIDITY IN THESE AREAS WAS IN THE TEENS OVERNIGHT, WHICH IS WHEN
YOU WOULD TYPICALLY EXPECT THE HIGHEST RH OF THE DAY. THE SOUNDING
FOUND AN INCREDIBLY DRY POCKET OF AIR BETWEEN 850 AND 700 MB,
WHERE THE AVERAGE RH IS ONLY 2%. THE COMBINED HOT, DRY, AND WINDY
CONDITIONS ARE MORE THAN ENOUGH TO REACH RED FLAG CRITERIA IN THE
NORTH AND EAST BAY MOUNTAINS TODAY, BUT WE STILL NEED THE ANNUAL
GRASSES TO CURE BEFORE THAT'S AN OPTION.
TYPICALLY THE GRASS CURES AND TURNS BROWN IN THE SUMMER, BUT THIS
YEAR IS AHEAD OF SCHEDULE. DOWNTOWN SAN FRANCISCO IS CURRENTLY
REPORTING THE WARMEST MARCH ON RECORD (BY A HEALTHY 1.5F IN TERMS
OF AVERAGE TEMPERATURE THROUGH MARCH 26TH) AND THE DRIEST MARCH
SINCE 1923 (ONLY 0.06" OF RAIN SO FAR, NORMAL FOR MARCH IS 3.15").
TO GET A SENSE OF THE LIVE FUEL MOISTURE I COMPARED HISTORICAL
POLAR ORBITING SATELLITE IMAGES FROM PAST YEARS (SEARCH "NASA
WORLDVIEW" TO SEE FOR YOURSELF). WE ARE SOMEWHERE BETWEEN A NORMAL
APRIL AND MAY IN TERMS OF BROWNNESS. FOR DEAD FUEL MOISTURE IT'S
EVEN MORE STARK. THE ENERGY RELEASE COMPONENTS ARE SETTING RECORDS
ACROSS THE CWA, WITH THE MID COAST TO MENDOCINO ERC NEAR THE
AVERAGE FOR EARLY JULY, AND DIABLO-SANTA CRUZ NEAR THE AVERAGE
FOR MID-JULY. THE BAY AREA MARINE ERC IS ACTUALLY ABOVE THE
AVERAGE FOR ANY TIME OF YEAR, AND EVEN CROSSED THE ANNUALIZED 97TH
PERCENTILE. WHILE THE HILLS STILL HAVE MORE GREEN THAN BROWN AND
WE'RE NOT EXPECTING LARGE WILDFIRES ANYTIME SOON, THE ANTECEDENT
CONDITIONS ARE SET UP FOR AN ACTIVE YEAR.
CLIMATE
ISSUED AT 952 PM PDT FRI MAR 27 2026
HERE ARE THE RECORD HIGH TEMPERATURES AT THE LONG TERM SITES FOR
MARCH 29TH.
LOCATION MARCH 29TH
SANTA ROSA 86 IN 2018
SAN RAFAEL 85 IN 2018
KENTFIELD 84 IN 1935
NAPA 83 IN 2018, 1968
RICHMOND 79 IN 1968
LIVERMORE 85 IN 2015
SAN FRANCISCO 81 IN 2018
SFO AIRPORT 81 IN 2018
REDWOOD CITY 85 IN 2018, 1968
HALF MOON BAY 77 IN 2004
OAKLAND 79 IN 2003
SAN JOSE 82 IN 2018
SALINAS AIRPORT 86 IN 2018
MTR WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 3 AM PDT SUNDAY FOR PT ARENA TO PT
REYES 10-60 NM.
SHORT TERM...FLYNN
LONG TERM....FLYNN
AVIATION...DIALH
MARINE...DIALH
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