094
FXUS66 KMTR 091823
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
1123 AM PDT WED JUL 9 2025
..NEW AVIATION, MARINE
KEY MESSAGES
UPDATED AT 101 AM PDT WED JUL 9 2025
- WARMING TREND BEGINS TODAY THROUGH THE WEEKEND, WITH PATCHY
MODERATE HEATRISK ACROSS THE BAY AREA AND CENTRAL COAST
THURSDAY AND FRIDAY.
- LOCALIZED ELEVATED FIRE WEATHER THREAT STARTING TODAY THROUGH
THE WEEKEND ACROSS THE HIGHER ELEVATIONS.
SHORT TERM
ISSUED AT 101 AM PDT WED JUL 9 2025
(TODAY AND TONIGHT)
SATELLITE IMAGERY SHOWS WIDESPREAD MARINE LAYER STRATUS ACROSS THE
VALLEYS OF THE BAY AREA AND CENTRAL COAST, AS DATA FROM THE FORT ORD
PROFILER SHOWS THE TOP OF THE MARINE LAYER BECOMING MORE DIFFUSE
WHILE RISING TO AT LEAST 3000 FEET OVER THE LAST EVENING. LOW
TEMPERATURES THIS MORNING WILL HOVER IN THE LOWER TO MIDDLE 50S IN
THE LOWER ELEVATIONS, AND AS HIGH AS THE LOWER 60S IN THE HIGHEST
PEAKS.
TODAY MARKS A PATTERN CHANGE FROM THE COOLER REGIME OF THE LAST FEW
DAYS TO A WARMING PATTERN THAT (SPOILER ALERT) LOOKS TO SET UP FOR
THE REST OF THE WEEK. THE UPPER LEVEL LOW THAT BROUGHT US THE ROBUST
MARINE LAYER AND THE COOL TEMPERATURES IS DISSIPATING WHILE IT
MEANDERS TOWARDS LANDFALL IN THE NORTH COAST. THIS WILL ALLOW AN
RIDGE THAT'S SET UP OVER THE DESERT SOUTHWEST TO EDGE INTO THE STATE
WHILE A SYNOPTIC HIGH PRESSURE SYSTEM DEVELOPS IN THE EAST PACIFIC,
CAUSING TEMPERATURES TO WARM. TEMPERATURES WILL RANGE FROM THE UPPER
70S TO THE MIDDLE 80S INLAND, WITH THE WARMEST SPOTS IN SOUTHERN
MONTEREY AND SAN BENITO COUNTIES REACHING THE UPPER 90S, WHILE
LOCATIONS ON THE BAYS REACH HIGHS IN THE UPPER 60S AND THE 70S. THE
MARINE LAYER WILL COMPRESS, BUT THE COASTAL AREAS SHOULD REMAIN
RATHER COOL WITH HIGHS IN THE UPPER 50S TO THE LOWER 60S.
SOME ELEVATED FIRE WEATHER THREAT IS FORECAST TO DEVELOP TODAY
ACROSS AREAS ABOVE AND INLAND OF THE MARINE LAYER'S INFLUENCE. THE
COMBINATION OF DRY DAYTIME HUMIDITIES OF AROUND 15-30% AND LOCALIZED
GUSTS TO 30 MP WILL BE THE MAIN FACTORS BEHIND THE ELEVATED THREAT.
HOWEVER, THE WINDS WILL REMAIN ONSHORE, LEADING TO THE FIRE WEATHER
THREAT BEING DIURNALLY DRIVEN, ESPECIALLY IN THE FOOTHILLS WHERE
LIGHTER WINDS AND GOOD OVERNIGHT RECOVERIES ARE EXPECTED EACH
NIGHT.
LONG TERM
ISSUED AT 101 AM PDT WED JUL 9 2025
(THURSDAY THROUGH TUESDAY)
TEMPERATURES CONTINUE TO RISE ON THURSDAY AND FRIDAY AS THE HIGH
PRESSURE SYSTEMS BECOME MORE ESTABLISHED, WITH THE INLAND VALLEYS
SEEING HIGHS IN THE MIDDLE 80S TO MIDDLE 90S ON BOTH DAYS, WHILE THE
WARMEST INTERIOR LOCATIONS SEE TEMPERATURES RISING UP TO A FEW
DEGREES ABOVE 100. PATCHES OF MODERATE HEATRISK ARE EXPECTED ON
THURSDAY AND FRIDAY ACROSS THE INTERIOR NORTH BAY, EAST BAY, AND
SOUTH BAY, IN ADDITION TO THE SANTA LUCIA MOUNTAINS AND THE SOUTHERN
TIP OF SAN BENITO COUNTY. REMEMBER TO TAKE FREQUENT COOLING BREAKS
AND DRINK PLENTY OF WATER IF PARTICIPATING IN OUTDOOR ACTIVITIES ON
BOTH DAYS.
AS A VERY WEAK UPPER LEVEL DISTURBANCE PASSES THROUGH THE STATE THIS
WEEKEND, TEMPERATURES WILL COOL SLIGHTLY TO THE LOWER 80S TO LOWER
90S IN THE INTERIOR BAY AREA WITH AN SHORTWAVE TROUGH COMING THROUGH
THE WEST COAST, WHILE THE INTERIOR CENTRAL COAST REMAINS RATHER WARM
WITH TEMPERATURES IN THE 90S. THE PATTERN WILL OTHERWISE REMAIN
RATHER STABLE THROUGH THE EARLY PART OF NEXT WEEK, WITH WARM INLAND
TEMPERATURES, COOL COASTAL TEMPERATURES, LIGHT ONSHORE WINDS, AND
LOCALIZED ELEVATED FIRE WEATHER THREAT IN THE INTERIOR DEVELOPING
EACH AFTERNOON.
AVIATION
(18Z TAFS)
ISSUED AT 1108 AM PDT WED JUL 9 2025
THE CEILINGS ARE CLEARING OUT WITH MOSTLY CLEAR SKIES EXPECTED
THROUGH THE AFTERNOON. THE EXCEPTION IS ALONG THE IMMEDIATE COAST,
WHERE IFR-MVFR CONDITIONS ARE POSSIBLE THROUGH THE DAY. THERE IS
A PATTERN SHIFT ONGOING TODAY AS HIGH PRESSURE BECOMES THE
DOMINANT FEATURE AND COMPRESSES THE MARINE LAYER. THIS WILL CAUSE
LESS EXPANSIVE STRATUS COVERAGE THURSDAY MORNING. ON THE OTHER
HAND CEILINGS AND VISIBILITY WILL BE LOWER FOR THE TERMINALS THAT
ARE CLOSE ENOUGH TO THE COAST TO REMAIN IN THE MARINE LAYER.
VICINITY OF SFO...THE CEILING SCATTERED OUT JUST BEFORE 18Z, AND
VFR CONDITIONS ARE VIRTUALLY GUARANTEED FOR THE NEXT SEVERAL
HOURS. THE UNCERTAINTY STARTS TO INCREASE AROUND 03Z. THE
PERSISTENCE FORECAST WOULD BRING MVFR CEILINGS BACK AT THIS TIME,
LOWERING TO IFR LATER IN THE NIGHT. HOWEVER, AS THE MARINE LAYER
COMPRESSES, THE STRATUS WON'T PUSH INLAND AS FAST. WITH NW WINDS
IN THE BOUNDARY LAYER, IT'S LIKELY THAT THE PENINSULA HILLS WILL
HELP PROTECT THE TERMINAL FROM AN EARLY CEILING RETURN. BY 12Z
THURSDAY MORNING, THERE IS A 50-60% CHANCE THAT SFO WILL DEVELOP A
CEILING. IF SO, THE HEIGHT WILL BE CLOSE TO THE MVRF/IFR
THRESHOLD. IN SUMMARY, THE CEILING TIMING AND HEIGHT CONFIDENCE
IS LOW BEYOND THE FIRST 9 HOURS OF THE TAF.
SFO BRIDGE APPROACH... SIMILAR TO SFO.
MONTEREY BAY TERMINALS...WITH A COMPRESSING MARINE LAYER, MRY WILL
SPEND MUCH LONGER UNDER A CEILING THAN SNS OVER THE NEXT COUPLE
DAYS. WITH NW WINDS THERE IS ALSO A GOOD CHANCE FOR LIFR CEILINGS
AND POSSIBLY FOG DEVELOPMENT IN THE EARLY MORNING.
MARINE
(TODAY THROUGH MONDAY)
ISSUED AT 1108 AM PDT WED JUL 9 2025
AS THE GRADIENT BETWEEN HIGH PRESSURE IN THE EAST PACIFIC AND
LOWER PRESSURE OVER THE INTERMOUNTAIN WEST INCREASES, FRESH TO
STRONG NW WINDS WILL DEVELOP THROUGH THE AFTERNOON AND EVENING.
THESE WINDS WILL MAINTAIN STRENGTH THROUGH THURSDAY, BUILDING
ROUGH SEAS IN THE EXPOSED WATERS.
MTR WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO 3 AM PDT
THURSDAY FOR PT ARENA TO PT REYES 0-10 NM-PT PINOS TO PT
PIEDRAS BLANCAS 0-10 NM.
SMALL CRAFT ADVISORY FROM 3 PM TO 9 PM PDT THURSDAY FOR PT ARENA
TO PT REYES 0-10 NM-PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM.
SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO 9 PM PDT
THURSDAY FOR PIGEON PT TO PT PINOS 10-60 NM-PT ARENA TO PT
REYES 10-60 NM.
SHORT TERM...DIALH
LONG TERM....DIALH
AVIATION...FLYNN
MARINE...FLYNN
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