052
FXUS66 KMTR 221150
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
450 AM PDT TUE SEP 22 2026
..NEW AVIATION, MARINE
KEY MESSAGES
UPDATED AT 1201 AM PDT TUE SEP 22 2026
- WARMING TREND BEGINS TODAY THROUGH THURSDAY
- COOLER CONDITIONS FRIDAY INTO THE WEEKEND
SHORT TERM
ISSUED AT 1201 AM PDT TUE SEP 22 2026
(TODAY AND TONIGHT)
EXTENSIVE STRATUS HAS FLOWED INTO THE NORTH BAY VALLEYS, MONTEREY
BAY REGION, SALINAS VALLEY, HOLLISTER AREA, AND THE EAST BAY WEST OF
THE BERKELEY HILLS. ACROSS THE REST OF THE SF BAY AREA, PATCHES OF
STRATUS HAVE DEVELOPED NEAR LIVERMORE AND NORTH OF SAN JOSE, WITH
FURTHER EXPANSION EXPECTED THROUGH THE PRE-DAWN HOURS. THE CLOUD
DECK RETREATS BACK TO THE IMMEDIATE COAST LATE THIS MORNING INTO THE
EARLY AFTERNOON, BUT BY THE TIME IT DEVELOPS AGAIN TONIGHT, THE
MARINE LAYER WILL BE COMPRESSED, LEADING TO UNCERTAINTY OVER JUST
HOW FAR INLAND THE CLOUDS WILL GO.
THE CUT-OFF LOW THAT GAVE US THE LAST COUPLE DAYS OF COOLER
TEMPERATURES IS MOVING ACROSS THE STATE WITH THE CENTER CRAWLING
THROUGH THE MOJAVE DESERT INTO THE GREAT BASIN. THIS ALLOWS FOR MORE
ZONAL FLOW TO COME INTO THE STATE AND A WARMING TREND TO BEGIN
TODAY, WITH HIGH TEMPERATURES IN THE UPPER 70S TO THE MIDDLE 80S
ACROSS THE INLAND VALLEYS, INTO THE UPPER 80S IN THE FAR INTERIOR
REGIONS OF THE NORTH BAY AND SOUTHERN MONTEREY COUNTY, THE MIDDLE
60S TO THE MIDDLE 70S CLOSE TO THE BAYS, AND THE LOWER TO MIDDLE 60S
ALONG THE IMMEDIATE COAST. A BREEZY ONSHORE WIND WILL DEVELOP IN THE
AFTERNOON AND EVENING HOURS, WITH THE STRONGEST GUSTS OF 20 TO 30
MILES PER HOUR ALONG THE COAST, THROUGH FAVORED GAPS AND PASSES, AND
WITHIN THE NORTHERN SALINAS VALLEY.
AS A QUICK SIDE NOTE, TODAY WILL MARK THE AUTUMNAL EQUINOX AND THE
START OF ASTRONOMICAL FALL. AT 505 PM PACIFIC TIME, THE SUN'S
APPARENT PATH ON THE EARTH CROSSES THE EQUATOR, GIVING US 12 HOURS
EACH OF SUNLIGHT AND NIGHTTIME.
LONG TERM
ISSUED AT 1201 AM PDT TUE SEP 22 2026
(WEDNESDAY THROUGH MONDAY)
SLIGHT RIDGING WILL DEVELOP OVER CALIFORNIA OVER THE NEXT COUPLE OF
DAYS, AND WHILE THE RIDGE AXIS QUICKLY MOVES INTO THE INTERMOUNTAIN
WEST, THE RIDGE INFLUENCE WILL ALLOW FOR FURTHER WARMING WEDNESDAY
AND THURSDAY. HIGH TEMPERATURES WARM INTO THE MIDDLE 80S TO THE
MIDDLE 90S IN THE INLAND VALLEYS, THE MIDDLE 70S TO THE MIDDLE 80S
CLOSE TO THE BAYS, AND THE MIDDLE 60S TO THE LOWER 70S ALONG THE
PACIFIC COAST. POCKETS OF MODERATE HEATRISK ARE SCATTERED ACROSS THE
INTERIOR REGIONS, PARTICULARLY NEAR SAN JOSE, THE INTERIOR EAST BAY,
AND THE SANTA LUCIA RANGE. THESE POCKETS ARE NOT EXPANSIVE ENOUGH TO
MERIT A HEAT ADVISORY.
BY FRIDAY, A DEVELOPING TROUGH IN THE EASTERN PACIFIC COMES INTO THE
WEST COAST, AND A COOLING TREND WILL CAUSE TEMPERATURES TO DIP NEAR
AND BELOW SEASONAL AVERAGES. WEEKEND HIGHS RANGE FROM THE MIDDLE 70S
TO THE MIDDLE 80S IN THE INLAND VALLEYS AND THE MIDDLE 60S TO THE
MIDDLE 70S CLOSE TO THE BAYS. TEMPERATURES WILL RECOVER EARLY NEXT
WEEK AS THE TROUGH FLATTENS AND ENSEMBLE MODEL CLUSTER ANALYSIS
HINTS AT A RIDGE DEVELOPING SOMEWHERE WITHIN THE WESTERN UNITED
STATES, ALTHOUGH THE EXACT IMPACTS ARE NOT CERTAIN AT THIS POINT.
AVIATION
(12Z TAFS)
ISSUED AT 427 AM PDT TUE SEP 22 2026
SOLID MARINE LAYER PUSH OVERNIGHT LEADING TO MOSTLY MVFR TO IFR
CONDITIONS. SEEING SOME COMPRESSION ON THE MARINE LAYER LEADING
TO SOME PATCHY FOG AND DZ/RA BEING REPORTED. EXPECT
CLEARING/ROLLING BACK TO THE COAST MID TO LATE MORNING MOST AREAS.
HAF AND MRY WILL HOLD ONTO CIGS FOR MOST OF THE DAY. TONIGHT, N-S
GRADIENT INCREASES SO LESS CONF FOR STRATUS N AND E BAY. OVERALL
CONF IS MODERATE.
VICINITY OF SFO...MUCH MORE OPTIMISTIC FOR THE TAF AS SE FLOW
CAUSED RAPID DRYING/CLEARING EARLIER IN THE NIGHT. STILL WATCHING
A BANK OF CLOUDS DUE E OF SFO INCHING W. CARRYING A TEMPO FOR NOW,
BUT CONF IS LOW ON ACTUAL IMPACTS TO TERMINAL.
SFO BRIDGE APPROACH...SIMILAR TO SFO. CIGS FAR E FRINGE OF
APPROACH.
MONTEREY BAY TERMINALS...IFR WITH LOW CIGS, BR, AND DZ/RA THROUGH
18Z-ISH . A FEW HOURS OF VFR THIS AFTERNOON, BUT CIGS AND
MVFR/IFR RETURN EARLY TONIGHT.
MARINE
(TODAY THROUGH SUNDAY)
ISSUED AT 427 AM PDT TUE SEP 22 2026
FRESH TO STRONG BREEZES WILL PREVAIL EARLY TUESDAY AS A WEAK COLD
FRONT SWEEPS THROUGH THE REGION. BEHIND THE FRONT MORE WIDESPREAD
STRONG BREEZES WILL PREVAIL THIS AFTERNOON. THE STRONGER WINDS
WILL RESULT IN HAZARDOUS CONDITIONS FOR SMALL CRAFT. NORTHWEST
BREEZES AND SEAS REMAIN ELEVATED THROUGH THE WEEK WITH A BRIEF
PERIOD OF IMPROVED CONDITIONS WEDNESDAY NIGHT INTO THURSDAY. BY
FRIDAY, WINDS INCREASE WITH BUILDING ROUGH SEAS.
FIRE WEATHER
ISSUED AT 434 AM PDT TUE SEP 22 2026
SOLID MARINE LAYER COVERAGE ALONG THE COAST AND SALINAS VALLEY
OVERNIGHT. SOUNDING AND PROFILERS PUT THE DEPTH OF THE MARINE
LAYER AROUND THE 2,000-2,500 FOOT RANGE. DEFINITELY SOME
COMPRESSION ON THE MARINE LAYER LEADING TO DRIZZLEFEST AROUND THE
AREA. SEEING SOME REDUCED VSBY TOO, WHICH MAY LEAD TO PATCHY FOG
EARLY THIS MORNING FOR CREWS DEPARTING ICP FOR TIMBER/PLASKETT.
ABOVE THE MARINE LAYER MODERATE TO EXCELLENT HUMIDITY RECOVERY
FOR THE MOST PART WITH THE DRIEST CONDITIONS ABOVE 3,000 FEET.
OTHERWISE, STILL VALID FOR A WARMING AND DRYING TREND KICKING OFF
TUESDAY WITH TEMPERATURES UP TO 10 DEGREES ABOVE NORMAL AND AREAS
OF MODERATE HEATRISK WEDNESDAY AND THURSDAY. THE MARINE LAYER WILL
COMPRESS BELOW 1,000 FEET DURING THIS WARM-UP WITH NOCTURNAL
DRYING EXPECTED ABOVE IT.
MM
MTR WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 5 AM PDT WEDNESDAY FOR PT ARENA TO PT
REYES 0-10 NM.
SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO 9 PM PDT THIS
EVENING FOR PIGEON PT TO PT PINOS 0-10 NM.
SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO 3 AM PDT
WEDNESDAY FOR PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM.
SMALL CRAFT ADVISORY UNTIL 3 AM PDT THURSDAY FOR PT ARENA TO PT
REYES 10-60 NM.
SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO 5 AM PDT
WEDNESDAY FOR PIGEON PT TO PT PINOS 10-60 NM.
SHORT TERM...DIALH
LONG TERM....DIALH
AVIATION...MM
MARINE...MM
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