369
FXUS66 KMTR 110448
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
948 PM PDT Mon Aug 10 2026

...New AVIATION, MARINE...

.KEY MESSAGES...
Updated at 144 PM PDT Mon Aug 10 2026

 - Elevated fire weather conditions in the higher terrain Monday

 - Minor coastal flooding for bayshore locations along the San Francisco
   Bay, San Pablo Bay, and Monterey Bay through Thursday morning

 - Cooling trend through Thursday will bring well below normal
   temperatures

 - Up to a 15% chance for elevated rain showers/thunderstorms
   Wednesday with high confidence over the Central Coast

&&

.SHORT TERM...
Issued at 144 PM PDT Mon Aug 10 2026
(This evening through Tuesday night)

Afternoon visible satellite imagery shows ample sunshine across
the interior, but the persistent marine layer continues to hug
the coast. Pretty interesting to see all of the small eddies
forming in the coastal stratus this afternoon as well. Satellite
imagery also shows heat and smoke associated with the Timber
Incident along the Big Sur coast. Monterey Airport was reporting
haze at various times through the day due to some drift smoke.
Overall transport flow is not overly strong through Tuesday so
smoke/haze will be possible around the Monterey Bay / Big Sur
region.

Interesting longwave pattern across CA tonight through Tuesday.
The large ridge that brought oppressive heat to CA over the
weekend has been split in half by a deepening upper level trough.
One upper ridge is near the Four Corners and the other is well
offshore. Sandwiched in the middle is a small shortwave trough
inching its way toward the CA coast. Over the next 24 hours the
trough will deepen further cooling the airmass and deepening the
marine layer. The cooling trend noticed across the forecast area
today will continue on Tuesday. Additionally, as the trough
deepens a few spokes of moisture and instability will traverse the
Central Coast. For now, not enough to warrant any mention of
precip, but a few high level Cu are possible. Speaking of precip,
the moisture in the marine layer will be high enough for coastal
drizzle.

&&

.LONG TERM...
Issued at 240 PM PDT Mon Aug 10 2026
(Wednesday through next Sunday)

For Wednesday an upstream feature gets enhanced by a jet max west
of Pt Conception. This feature has peaked our interest as it will
lead to a low confidence high impact scenario. Latest model
guidance shows there is enough moisture and instability to at
least warrant a mention of showers and thunderstorms. Pt forecast
soundings shows decent instability, dry low levels, but some CIN
leading to the lower confidence. Pattern recognition also brings
some pause as previous fires in 1999 and 2008 had upper level
disturbances off the Central Coastal. This setup is close, but
not exactly like previous lightning busts. As such, decided to not
issue any Fire Weather Headline, but add 15% chc of
showers/thunderstorms to Monterey/San Benito Wednesday afternoon
and evening. Outside of the convective threat, sensible weather
trends continues. Cooler weather for Wednesday and Thursday. Night
and morning clouds clearing to the coast each afternoon. Coastal
drizzle has been added to the forecast.

Over the weekend a subtle warming trend develops as a low deepens
near the Gulf of AK and drops south. The southward trajectory well
offshore of the West Coast will also the inland Four Corners
ridge to ease westward.

&&

.AVIATION...
(06Z TAFS)
Issued at 935 PM PDT Mon Aug 10 2026

VFR across all terminals except Monterey Bay sites and KHAF. The
marine layer will continue to gradually increase through the
forecast period with increased coverage expected than what was
seen last night into this morning. Local offshore eddys will
complicate timing once again, especially for the Bay Area.

Vicinity of SFO...VFR with until after midnight with local
offshore eddys continuing to complicate exact timing of stratus.
The marine layer is expected to progress farther inland tonight.
KOAK may not see MVFR/IFR ceilings until the predawn hours with
KSFO potentially not being impacted despite more extensive
coverage of stratus due to the eddys.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...MVFR/IFR ceilings will persist through
the remainder of the overnight with a slight chance of continuing
through the entire forecast period as the marine layer gradually
increases through the day tomorrow with steady onshore flow,
breezy at times in the afternoon.

&&

.MARINE...
(Tonight through next Sunday)
Issued at 935 PM PDT Mon Aug 10 2026

Fresh to strong northwest winds will continue to produce rough
seas up to 13 feet across the northern outer waters through
Thursday. Long period southerly swell will gradually increase from
15 seconds through the middle of the week, up to 19 seconds by
Friday into Saturday.

&&

.FIRE WEATHER...
Issued at 205 PM PDT Mon Aug 10 2026

Timber Fire - complicated weather around the vicinity of the
Timber Fire. There will be a vast difference is weather along Hwy
1 and along Coast Ridge Rd. The marine layer will keep the Hwy 1
region cool, damp, and drizzly. Above the marine layer will
remain mild and dry. Above the marine layer is also a region that
has baked and dried over the last 7 to 10 days with little to no
relief. Thankfully, wind does not appear to be overly strong.
Very diurnally driven wind patterns.

The real wild card for the Timber Fire will be thunderstorm
chances on Wednesday. REad the long term above for more details.
After coordinating with neighboring offices and fire partners
decided to mention the chance and not issue any Red Flag at this
time.

MM

From the previous discussion, which is still valid for today. May
obs as of 230PM show RH less than 20% and winds gusts 10-20 mph.

Elevated fire weather conditions persist Monday across the higher
terrain due to an increase in onshore flow on the heels of very hot
and dry conditions. Slow improvement is expected with temperatures
still 10 degrees above normal and minimum relative humidity of 15%-
30% Monday afternoon. Gusts up to 30 mph can be expected through
gaps/passes and across ridgelines; namely, the Delta, Altamont Pass,
Pacheco Pass, and Interior Mountains of Monterey and San Benito
Counties. Moderate overnight recovery is expected Monday night;
however, the highest terrain of the Central Coast will likely remain
poor.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Coastal Flood Advisory until 2 AM PDT Thursday for CAZ006-506-
     508-529-530.

PZ...Small Craft Advisory until 9 AM PDT Thursday for Pt Arena to Pt
     Reyes 10-60 NM.

&&

$$

SHORT TERM...MM
LONG TERM....MM
AVIATION...JM
MARINE...JM

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