003
FXUS66 KMTR 121207
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
507 AM PDT FRI SEP 12 2025
..NEW AVIATION, MARINE
KEY MESSAGES
UPDATED AT 240 AM PDT THU SEP 12 2025
- DRIER AND SLIGHTLY WARMER WEATHER FRIDAY AND SATURDAY, MUCH
WARMER EARLY NEXT WEEK WITH MODERATE HEATRISK
SHORT TERM
ISSUED AT 311 AM PDT FRI SEP 12 2025
(TODAY AND TONIGHT)
MARINE LAYER IS TRYING TO MAKE A COMEBACK AS NOTED ON THE
OVERNIGHT SATELLITE FOG PRODUCT AND THE BODEGA BAY PROFILER. THE
DEPTH OF THE MARINE LAYER IS CLOSE TO 1500 FEET PER PROFILER,
WHICH IS CLOSE TO MOISTURE X-SECTIONS ON MODEL GUIDANCE. INLAND
CLOUDS WILL SLOWLY ROLL BACK TO THE COAST MID-LATE MORNING, BUT
NOT EXPECTING A FULL CLEARING AT THE COAST. CLOUDS WILL LINGER
FOR MOST OF THE DAY. THE LONGWAVE PATTERN IN THE WEST IS STILL
GRIPPED BY A POSITIVELY TILTED UPPER TROUGH AND EMBEDDED UPPER
LOW. THIS FEATURE CONTINUES TO WEAKEN AND MOVE EASTERLY INTO WHAT
WILL BE AN OPEN WAVE. WAITING IN THE UPPER LEVEL WINGS IS
SHORTWAVE RIDGING. TODAY WILL BE A TRANSITION DAY IN THE LONGWAVE
PATTERN FROM A TROUGH TO A RIDGE. DESPITE SOME COASTAL CLOUDS, DO
EXPECT AN UPTICK (5-10 DEGREES) IN TEMPERATURES TODAY WITH THE
APPROACHING RIDGE.
ONE OTHER ITEM OF NOTE WE'LL BE MONITOR THIS AFTERNOON WILL BE
WILDFIRE SMOKE. WHILE ONE WOULD THINK IT WOULD BE FROM THE GARNET
FIRE OVER ON THE SIERRA IT'S ACTUALLY FIRES BURNING IN WA. GIVEN
THE UPPER LEVEL PATTERN SOME UPPER LEVEL SMOKE WILL BE POSSIBLE.
MORE LIKE SOME UPPER LEVEL HAZE. NO SURFACE SMOKE IS EXPECTED.
A MORE DEFINED MARINE LAYER WILL RETURN TONIGHT WITH A SLIGHTLY
DEEPER PUSH. SOLID HUMIDITY RECOVERY IS EXPECTED OVERNIGHT, BUT
THE HIGHEST PEAKS ABOVE 3-4K FEET WILL BE MODERATE HUMIDITY
RECOVERY AND IN AN ACTIVE THERMAL BELT.
LONG TERM
ISSUED AT 331 AM PDT FRI SEP 12 2025
(SATURDAY THROUGH THURSDAY)
LOOKING PRETTY DRY FOR THE UPCOMING WEEKEND. PREVIOUS MODEL RUNS
BROUGHT A FEW SHOWERS TO NORTHERN AREAS ON SUNDAY, BUT THE 00Z
RUNS HAVE ALL BUT ERASED IT. IN FACT, THE UPCOMING WEEKEND IS
TRENDING WARMER AND DRIER THAN PREVIOUS FORECAST. THE SHORTWAVE
RIDGE WILL SLIDE THROUGH SATURDAY WITH SHORTWAVE TROUGH TO QUICKLY
FOLLOW ON SUNDAY. THE RIDGE WILL CONTINUE THE SUBTLE WARMING
TREND ON SATURDAY WITH HIGHS RANGING FROM THE 60S/70S COAST AND
70S TO NEAR 90 INLAND. TEMPERATURES MODERATE ON SUNDAY AS A TROUGH
PASSES TO THE NORTH. THE PASSING TROUGH HAS A BETTER SHOT AT
PRODUCING PRECIP NORTH OF THE BAY AREA.
TO JUMP START THE WORK WEEK WILL BE ANOTHER UPPER LEVEL RIDGE. THE
HIGHER 500MB HEIGHTS AND WARMER 850MB WILL REINVIGORATE THE
WARMING AND DRYING TREND. BY TUESDAY AND WEDNESDAY 850MB TEMPS
REACH THE LOW 20C RANGE. IF YOU DO THE OLD RULE OF THUMB FOR A
MIXED ATMOSPHERE AND ADD 10-15C YOU CAN GET SURFACE TEMPERATURES
OF 95-100 DEGREES. THOSE VALUES ARE CURRENTLY IN THE FORECAST FOR
FAR INTERIOR LOCATIONS. LINGERING ONSHORE FLOW AND MARINE
INFLUENCE WILL KEEP THE COAST AND BAYS COOLER AND IN THE 70S AND
80S. REGARDLESS, TEMPERATURES WILL BE SEVERAL DEGREES ABOVE
NORMAL. HEATRISK VALUES AWAY FROM THE COAST DO SURGE INTO THE
MODERATE CATEGORY WITH A FEW PIXELS OF MAJOR.
NEXT THURSDAY AND BEYOND GET PRETTY INTERESTING ON THE LONG RANGE
FORECAST. KIND OF FANTASY LAND AT THIS POINT, BUT THERE ARE SIGNS
WE'LL NEED TO WATCH FOR ANOTHER ROUND OF TROPICAL/MONSOONAL
MOISTURE SURGE. IT'S TOO EARLY FOR DETAILS, BUT LONGER RANGE
GLOBAL ENSEMBLES/CLUSTER SHOW TRANSPORT FLOW THAT WOULD BRING
DECAYING TROPICAL SYSTEM MOISTURE WITH A HINT OF MONSOONAL. GFS
MODEL FOR INSTANCE HANDLED THE EARLY SEPTEMBER LIGHTNING EVENT
BETTER THAN OTHERS. IT'S FANTASY LAND PICTURE FOR THE 19-20TH OF
SEPT SHOWS SHOWERS AND THUNDERSTORMS OVER CENTRAL CALIFORNIA. AT
THIS POINT, IT WORTH KEEPING AND EYE ON. TIMING WOULD BE BAD FROM
A FIRE WEATHER STAND POINT AS WARMER WEATHER DEVELOPS OVER THE
WEEKEND AND PEAKS EARLY NEXT WEEK.
AVIATION
(12Z TAFS)
ISSUED AT 507 AM PDT FRI SEP 12 2025
MIX OF IFR-MVFR CEILINGS ACROSS THE BOARD THIS MORNING. WE ARE
STARTING TO SEE THE RETURN OF A MORE TYPICAL MARINE LAYER PATTERN
WITH STRATUS EXTENDING ACROSS MOST OF THE BAY AREA AND CENTRAL
COAST. THIS SLIGHTLY INCREASES CONFIDENCE IN STRATUS CLEARING BY MID
TO LATE MORNING. THE EXCEPTION IS HAF WHERE STRATUS LOOKS TO PERSIST
ALL DAY. FOR MRY AND SNS, WENT WITH A BRIEF PERIOD OF CLEARING BUT
SOME ENSEMBLE MEMBERS DO PUSH FOR STRATUS TO PERSIST THROUGH THE
ENTIRE TAF PERIOD. STRATUS RETURNS LATE THIS EVENING WITH MODERATE
CONFIDENCE IN CIGS STAYING MVFR WITH SOME SITES GRADUALLY DROPPING
TO IFR OVERNIGHT.
VICINITY OF SFO...MVFR THROUGH LATE MORNING BEFORE MVFR CIGS RETURN
THIS EVENING. MODERATE CONFIDENCE THAT SFO WILL CLEAR BY 18Z WHICH
MATCHES UP WELL WITH LAMP GUIDANCE. KEPT THE STRATUS RETURN AROUND
05Z WHICH AGREES WELL WITH THE WRF. THE LAMP PUSHES FOR AN EARLIER
RETURN OF STRATUS CLOSER TO 01-02Z BUT CONFIDENCE IS LOWER IN THAT
SOLUTION.
SFO BRIDGE APPROACH...SIMILAR TO SFO.
MONTEREY BAY TERMINALS...IFR CIGS ARE EXPECTED TO RISE AND BECOME
MVFR BY LATER THIS MORNING. LOW TO MODERATE CONFIDENCE THAT STRATUS
WILL CLEAR BY LATE MORNING/EARLY AFTERNOON. SOME ENSEMBLE MEMBERS
SHOW STRATUS PERSISTING THROUGH THE ENTIRE TAF PERIOD BUT CONFIDENCE
IS ON THE LOWER END FOR THAT SCENARIO. LEANING TOWARDS A BRIEF 3-4
HOUR PERIOD OF VFR CONDITIONS BEFORE MVFR-IFR CIGS RETURN OVERNIGHT.
CURRENT THINKING IS THAT MVFR CIGS WILL GRADUALLY LOWER TO IFR
TONIGHT BUT IF THE MARINE LAYER COMES IN LOWER THAN CURRENTLY
EXPECTED, INITIAL CIGS COULD START OUT AS IFR WITH A LOW POTENTIAL
FOR LIFR CIGS TOWARDS THE END OF THE TAF PERIOD.
MARINE
(TODAY THROUGH WEDNESDAY)
ISSUED AT 507 AM PDT FRI SEP 12 2025
BREEZY NW WINDS AND FRESH GUSTS ARE EXPECTED TODAY WITH LOCALLY
STRONGER GUSTS POSSIBLE ACROSS THE NORTHERN OUTER WATERS AND ALONG
THE BIG SUR COASTLINE. ROUGH SEAS PERSIST ACROSS THE OUTER WATERS
WHILE MORE MODERATE SEAS PERSIST ACROSS THE INNER WATERS. WINDS
DECREASE SATURDAY AS FRESH TO STRONG GUSTS BECOME MORE LOCALIZED
ACROSS THE SOUTHERN COASTAL WATERS. ANOTHER ROUND OF WIDESPREAD
FRESH TO STRONG NW WINDS BEGINS SUNDAY INTO NEXT WEEK WITH THE
STRONGEST WINDS LOCATED ACROSS THE FAR NORTHERN OUTER WATERS.
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 9 AM THIS MORNING TO 3 AM PDT SATURDAY
FOR PT ARENA TO PT REYES 0-10 NM.
SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO 3 AM PDT
SATURDAY FOR PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM.
SMALL CRAFT ADVISORY UNTIL 3 AM PDT SATURDAY FOR PT ARENA TO PT
REYES 10-60 NM.
SHORT TERM...MM
LONG TERM....MM
AVIATION...KENNEDY
MARINE...KENNEDY
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