FXUS66 KMTR 192048
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
148 PM PDT Wed Aug 19 2026
...New SHORT TERM, LONG TERM, MARINE...
.KEY MESSAGES...
Updated at 147 PM PDT Wed Aug 19 2026
- Compressed marine layer today, increases Thursday into the weekend
- A gradual cooling kicks off Thursday and continues into the
weekend
- Elevations above about 1000 feet will have warm temperatures
and RH values in the teens Thursday morning and afternoon
&&
.SHORT TERM...
Issued at 147 PM PDT Wed Aug 19 2026
(This evening through Thursday night)
Little change to the forecast as we shift from quasi-ridging to more
zonal flow in the upper levels over the next day. An upper level low
will slowly advance towards the West Coast, nudging the Desert
Southwest high slightly eastward. This will allow a cooling tend to
start on Thursday, in addition to the marine layer deepening and
onshore flow increasing. The marine layer should get to 1000-1200ft
by Thursday morning, leading to another night with wide spread
stratus, patchy fog, and patchy coastal drizzle. Elevations above
the marine layer, wont' be as lucky and will continue to be warm and
dry above it. Clouds begin to clear by early to mid morning, with
the stratus retreating to the coast by late morning. High clouds
look to return to the forecast tomorrow which should leave us with
partly to mostly cloudy skies. High temperatures will likely be a
couple of degrees cooler than Wednesday.
&&
.LONG TERM...
Issued at 147 PM PDT Wed Aug 19 2026
(Friday through next Tuesday)
The upper level low continues to track towards the West Coast, with
the trough elongating southwards and the shortwave or closed low
moving towards the PacNW by Saturday. Troughing holds over the
region through early next week, which will lead to temperatures
being anywhere from 5 to 15 degrees below their seasonal normal.
Stratus looks promising each night through at least Saturday
morning, with the marine layer potentially compressing Saturday
night into Sunday morning. Models suggest it could deepen again
Sunday night into Monday morning, which may lead to more widespread
stratus.
&&
.AVIATION...
(18Z TAFS)
Issued at 1027 AM PDT Wed Aug 19 2026
A mix of IFR/MVFR conditions this morning with high confidence of
stratus to retreat to the coastline late this morning and more so
by this afternoon. This will give way to VFR conditions this
afternoon across inland TAF sites. Increasing onshore flow will
persist throughout the afternoon and early evening hours before
diminishing late evening. Stratus and reduced visibilities return
first around the Monterey Bay terminals and then across the Bay
Area terminals late in the night and into Thursday morning.
Vicinity of SFO...VFR. Onshore winds increase this afternoon with
gusts up to 25 kt through the early evening. Low to moderate
confidence in the return of stratus tonight with some models
suggesting the low cloud cover will remain confined over OAK.
However, opted for IFR/MVFR ceilings over the terminal due to
persistence and LAMP guidance. However, this will need to be
monitored closely throughout the night. Onshore winds increase
Thursday afternoon with similar clearing time as today if not a
bit earlier.
SFO Bridge Approach...Low to moderate confidence for MVFR
ceilings to return early Thursday morning. Otherwise, similar to
SFO.
Monterey Bay Terminals...IFR, giving way to VFR by late morning
into early afternoon. Onshore winds increase this afternoon with
moderate to high confidence of IFR conditions returning late this
evening and lowering to LIFR late in the night.
&&
.MARINE...
(Tonight through next Monday)
Issued at 147 PM PDT Wed Aug 19 2026
Moderate to fresh northwesterly breezes with strong gusts across
the northern outer waters and along the coastal jet regions will
bring hazardous conditions for small craft periodically through
the weekend. Breezy fresh winds are expected across the San Pablo
Bay and the San Francisco Bay with locally stronger gusts possible
where terrain promotes wind funneling. Rough seas in the outer
waters will subside Thursday with moderate seas prevailing by
Friday.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 3 AM PDT Friday 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 Pigeon
Pt to Pt Pinos 0-10 nm.
Small Craft Advisory until 3 AM PDT Friday for Pt Arena to Pt
Reyes 10-60 NM.
&&
$$
SHORT TERM...KR
LONG TERM....KR
AVIATION...RGass
MARINE...RGass
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Prepared by Boulder-Creek.com Weather at: Wed Aug 19 14:30:03 PDT 2026
From the National Weather Service
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