FXUS66 KMTR 151144
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
444 AM PDT Sat Aug 15 2026
...New AVIATION, MARINE...
.KEY MESSAGES...
Updated at 1049 PM PDT Fri Aug 14 2026
- Gradual warming and drying trend Saturday and into next week
&&
.SHORT TERM...
Issued at 1049 PM PDT Fri Aug 14 2026
(Tonight through Sunday)
The region will remain on the eastern periphery of upper-level
troughing well off the West Coast Saturday. Sensible weather wise,
this'll bring another Fogust day with temperatures well below
normal, clouds in the evenings/mornings with a chance for drizzle,
and onshore flow. Gusts of 20-30 mph can be expected through
gaps/passes and down the Salinas Valley. While the marine layer
remains deep, it doesn't look healthy on satellite with patchwork
stratus across the region. Diurnal winds will keep smoke from the
Timber Fire out to sea with downsloping (easterly) winds in the
morning and onshore (northwesterly) winds in the afternoon.
&&
.LONG TERM...
Issued at 1049 PM PDT Fri Aug 14 2026
(Sunday night through next Friday)
Upper-level ridging will nose in from the east on Sunday and
ultimately anchor itself across the Desert Southwest on Tuesday.
This will result in a gradual warming and drying trend into next
week. Temperatures will moderate to near seasonal normals away from
and above the marine layer influence at the coast. As the marine
layer compresses with subsidence aloft, its footprint will become
smaller and conditions above it will become drier. Poor afternoon
daytime relative humidity of 20-30% is expected for the higher
terrain with locally lower values of 10-20% across the Central
Coast. Recovery will remain moderate through the weekend, but by
Monday little-to-none is expected with that trend continuing through
Friday. This will likely lead to seasonably elevated conditions with
rapid rates of spread on any wind-and-terrain aligned starts in
receptive vegetation. The timeframe of most concern will be with the
diurnal sea breeze in the afternoons/evenings.
&&
.AVIATION...
(12Z TAFS)
Issued at 432 AM PDT Sat Aug 15 2026
A deep marine layer is bringing widespread stratus to all Bay Area
and Monterey Peninsula Airports. Highest confidence in MVFR CIGs
with IFR across the North Bay Valleys and along the coast.
Ensembles show a decent chance for clearing between 17-18Z but the
deeper/substantial marine layer typically takes longer to clear
than models expect so I kept the the later clearing times in the
TAFs (18-20Z). The biggest tweak was to MRY where I added in a
brief period of VFR conditions this afternoon before an early
return of stratus. MVFR-IFR CIGs are expected again tonight.
Diurnally breezy onshore winds continue with lighter winds
overnight.
Vicinity of SFO...MVFR CIGs with drizzle through late morning.
LAMP probabilistic guidance shows a low chance for IFR CIGs this
morning but confidence is low that CIGs will drop below 1000 feet.
Stratus clears between 18-20Z with VFR then persisting through the
evening. Stratus returns late evening/overnight and persists
through the remainder of the TAF period.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...MVFR with IFR CIGs to at least
temporarily develop this morning. Highest confidence in IFR CIGs
impacting MRY over SNS but it cannot be fully ruled out there.
Went slightly more optimistic for the MRY TAF and included a brief
period of VFR this afternoon. Ensembles were more optimistic that
cloud cover would recede along the coast and HRRR guidance
suggested reductions in humidity (proxy for cloud cover) starting
around 20Z. Regardless, stratus comes back to both sites by the
early evening and persists through the rest of the TAF period.
CIGs initially start out MVFR but are expected to lower to IFR.
Not anticipating LIFR CIGs tonight but with the marine layer
compressing and ridging starting to push in, it may be possible
CIGs lower further than currently expected.
&&
.MARINE...
(Today through Thursday)
Issued at 432 AM PDT Sat Aug 15 2026
A gentle to moderate northwesterly breeze persists into early next
week with localized fresh gusts possible across the interior
waters. A long period southerly swell of about 16 to 18 seconds
will linger through Sunday. Winds increase to fresh to strong
early next week and remain elevated through the end of the
forecast period. Seas subside this weekend before building to 7 to
9 feet mid week.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...None.
&&
$$
SHORT TERM...Sarment
LONG TERM....Sarment
AVIATION...Kennedy
MARINE...Kennedy
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Prepared by Boulder-Creek.com Weather at: Sat Aug 15 08:30:02 PDT 2026
From the National Weather Service
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