444
FXUS66 KMTR 131755
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
1055 AM PDT SAT SEP 13 2025
..NEW AVIATION
KEY MESSAGES
UPDATED AT 120 AM PDT SAT SEP 13 2025
- TEMPERATURES AROUND OR SLIGHTLY BELOW NORMAL TODAY AND SUNDAY
- MUCH WARMER TEMPERATURES FOR THE FIRST HALF OF THE UPCOMING
WORK WEEK
- MODERATE HEATRISK POSSIBLE INLAND MONDAY THROUGH WEDNESDAY
UPDATE
ISSUED AT 840 AM PDT SAT SEP 13 2025
STRATUS HAS PUSHED A BIT FURTHER INLAND THIS MORNING COMPARED TO 24
HOURS AGO AS THE MARINE LAYER HAD DEEPENED TO AROUND 2,000 FEET.
EXPECTING CLOUD COVER TO RETREAT TO THE COAST AS WE MOVE INTO THE
AFTERNOON WITH TEMPERATURES REACHING INTO THE MID-TO-UPPER 80S
ACROSS THE INTERIOR, LOW-TO-UPPER 70S AROUND THE BAY SHORELINE, AND
GENERALLY MID 60S TO LOWER 70S IN COASTAL AREAS. OTHERWISE, THE
ONGOING FORECAST REMAINS ON TRACK. NO UPDATES NEEDED AT THIS TIME.
RGASS
SHORT TERM
ISSUED AT 120 AM PDT SAT SEP 13 2025
(TODAY AND TONIGHT)
COVERAGE OF LOW STRATUS IS INCREASING OVERNIGHT. THE MARINE LAYER
HAS BUILT UP TO AROUND 2000FT ALLOWING FOR A FARTHER INTRUSION
INLAND. LOW CLOUD DECK SHOULD ERODE INLAND BY LATE MORNING, LIKELY
BY EARLY AFTERNOON CLOSER TO THE COAST. PORTIONS OF THE IMMEDIATE
COAST FROM THE BAY AREA DOWN TO MONTEREY BAY MAY HAVE LOW CLOUDS
LINGER THROUGHOUT THE ENTIRE DAY, EVEN AS THE MARINE LAYER
RETREATS BACK TO THE COASTLINE. DESPITE THE PASSAGE OF A
PROGRESSIVE, AMPLIFIED RIDGE ACROSS THE WEST COAST TODAY, HIGHS
WILL REMAIN NEAR OR SLIGHTLY BELOW NORMAL. OVERNIGHTS LOWS INTO
SUNDAY MORNING WILL GENERALLY BE IN THE MID 50S TO LOW 60S.
LONG TERM
ISSUED AT 120 AM PDT SAT SEP 13 2025
(SUNDAY THROUGH FRIDAY)
AN UPPER TROUGH IN THE WAKE OF THE PROGRESSIVE RIDGING TODAY WILL
PUSH A WEAK COLD FRONT THROUGH OUR AREA SUNDAY, WITH LITTLE TO NO
EFFECT ON TEMPERATURES. THE PRIMARY CONCERN FOR THE EXTENDED
FORECAST WILL BE HEATRISK FOR THE FIRST HALF OF THE UPCOMING WORK
WEEK. A BROAD UPPER LEVEL RIDGE BEGINS TO DEVELOP OVER THE EASTERN
PACIFIC ON MONDAY. A PERIOD OF WEAK OFFSHORE FLOW MONDAY MORNING
THROUGH TUESDAY MORNING WILL LIFT TEMPERATURES ABOVE NORMAL, WITH
BIGGEST IMPACTS BEING FELT CLOSER TO THE COAST AS THE MARINE LAYER
ERODES. THE EAST BAY HILLS, PORTIONS OF THE SOUTH BAY AND
SOUTHERN MONTEREY COUNTY MAY SEE HIGHS IN THE UPPER 90S
APPROACHING 100 MONDAY THROUGH WEDNESDAY. SOME UNCERTAINTY REMAINS
IN THE UPPER LEVEL PATTERN. THE ECMWF HAS AN UPPER LEVEL LOW
UNDERCUTTING THE BASE OF THE RIDGE CLOSER TO OUR LATITUDE WITH THE
GFS MUCH FARTHER SOUTH LATE TUESDAY INTO WEDNESDAY. WILL WAIT TO
START MESSAGING MORE IMPACTFUL HEAT UNTIL BETTER CONSENSUS IS
REACHED IN GUIDANCE. NBM SEEMS REASONABLE AT THIS POINT, BUT DID
STILL BUMP TEMPERATURES UP MON-WED. CONFIDENCE IN THE PATTERN AND
RESULTING WEATHER IS EVEN LOWER INTO LATE NEXT WEEK AND WEEKEND.
AVIATION
(18Z TAFS)
ISSUED AT 1053 AM PDT SAT SEP 13 2025
A MIX OF IFR/MVFR CONDITIONS PERSIST THIS MORNING WITH HIGH
CONFIDENCE FOR VFR THIS AFTERNOON ACROSS INTERIOR AREAS. ONSHORE
WINDS WILL INCREASE BEFORE EASING AFTER SUNSET AND MORE SO INTO
SUNDAY MORNING. GENERALLY MODERATE CONFIDENCE FOR IFR/MVFR
CONDITIONS TO RETURN LATE AFTERNOON ACROSS THE MONTEREY BAY REGION
AND LATE EVENING ACROSS THE BAY AREA TERMINALS. THE HRRR SHOWS
LITTLE INDICATION OF LOW CEILINGS RETURNING, ESPECIALLY OVER THE BAY
AREA TERMINALS. HOWEVER, OTHER GUIDANCE INCLUDING THE LAMP SHOWS A
RETURN IN THE AFOREMENTIONED TIMEFRAME. THIS IS LIKELY DUE TO A DRY
FRONTAL BOUNDARY APPROACHING FROM THE NORTH LATE TONIGHT INTO SUNDAY
MORNING.
VICINITY OF SFO...HIGH CONFIDENCE FOR ONSHORE WINDS TO INCREASE THIS
AFTERNOON BEFORE EASING INTO EARLY SUNDAY MORNING. MODERATE
CONFIDENCE FOR MVFR CONDITIONS TO RETURN LATE THIS EVENING AND
PERSIST INTO MID-MORNING ON SUNDAY. LOW CONFIDENCE FOR SUB-MVFR
CONDITIONS EARLY SUNDAY MORNING. EARLIER CLEARING IS EXPECTED SUNDAY
MORNING BETWEEN 16Z-18Z AS THE MARINE LAYER BECOMES MIXED OUT BY THE
APPROACHING DRY FRONTAL BOUNDARY. ONSHORE WINDS INCREASE ONCE AGAIN
SUNDAY AFTERNOON.
SFO BRIDGE APPROACH...SIMILAR TO SFO.
MONTEREY BAY TERMINALS...MODERATE TO HIGH CONFIDENCE FOR VFR
CONDITIONS TO RETURN BRIEFLY THIS AFTERNOON WITH INCREASING ONSHORE
WINDS. MODERATE CONFIDENCE FOR IFR/MVFR CEILINGS RETURN LATE
AFTERNOON AND PERSIST THROUGH THE NIGHT AS WINDS EASE.
MARINE
(TODAY THROUGH THURSDAY)
ISSUED AT 840 AM PDT SAT SEP 13 2025
NORTHWESTERLY WINDS ARE FORECAST TO INCREASE SATURDAY AFTERNOON
WITH FRESH TO STRONG BREEZES ALONG PROMINENT COASTAL JET AREAS.
MODERATE SEAS PERSIST, ESPECIALLY OFFSHORE. MORE WIDESPREAD FRESH
TO STRONG BREEZES BUILD ACROSS THE REST OF THE WATERS INTO SUNDAY
AFTERNOON BEFORE SUBSIDING INTO THE BEGINNING OF NEXT WEEK.
MTR WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO 9 PM PDT THIS
EVENING FOR MRY BAY-PIGEON PT TO PT PINOS 0-10 NM.
SMALL CRAFT ADVISORY FROM 3 PM TO 9 PM PDT SUNDAY FOR MRY BAY-
PIGEON PT TO PT PINOS 0-10 NM.
SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO 3 AM PDT SUNDAY
FOR PT ARENA TO PT REYES 0-10 NM.
SMALL CRAFT ADVISORY FROM 3 PM SUNDAY TO 3 AM PDT MONDAY FOR PT
ARENA TO PT REYES 0-10 NM-PT ARENA TO PT REYES 10-60 NM.
SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO 3 AM PDT MONDAY
FOR PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM.
SHORT TERM...JM
LONG TERM....JM
AVIATION...RGASS
MARINE...RGASS
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