FXUS66 KMTR 310622
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1122 PM PDT Sun Aug 30 2026

...New SHORT TERM, LONG TERM...

.KEY MESSAGES...
Updated at 1004 PM PDT Sun Aug 30 2026

 - Morning drizzle likely along the coast

 - Cooler weather continues this week

 - Chance for light rain Wed-Thu in North Bay

&&

.SHORT TERM...
Issued at 1004 PM PDT Sun Aug 30 2026
(Tonight through Tuesday)

Marine layer stratus is becoming much better organized than 24
hours ago. Low clouds now cover the entire coast south of Pt.
Reyes. With a deeper, more organized marine layer, high 
resolution models are suggesting coastal drizzle is likely Monday
and Tuesday morning.

The troughing pattern will deepen over the next 48 hours, keeping
high temperatures 5-15 degrees below normal for this time of year.
According to the ECMWF ensemble, there is an 90% chance the 850 
mb temperature will drop below 12 C on Tuesday, which is the 
bottom 10th percentile for this time of year. As the trough axis 
approaches the coast, there is a good chance (roughly 70%) that 
the North Bay will get some light rain starting Tuesday.

&&

.LONG TERM...
Issued at 1004 PM PDT Sun Aug 30 2026
(Tuesday night through next Sunday)

The jet stream becomes highly meridional (north to south) by 
Wednesday. This makes the forecast more challenging. The 500 mb 
low will linger around the Pacific Northwest, but the exact track 
becomes much less certain, and the models are split if it will 
become completely cut-off from the jet stream later this week or 
not. Either way the cooler weather and occasional light rain 
chances will continue through the rest of the week. The exact evolution
of this low could have a major impact on the weather next weekend
and beyond.

First some background. There is an tropical disturbance in the 
Eastern Pacific well offshore SW Mexico. The National Hurricane 
Center is currently calling this system Invest Area 95E as they 
monitor for the further development needed to earn a name. This 
system has a 90% chance of formation into a tropical depression in
the next 48 hours, and has a high chance of becoming a hurricane 
by mid-week. This would be the 13th tropical cyclone in the 
Eastern Pacific this season, so why am I writing about it?

Tropical cyclones are steered by large scale, mid-tropospheric
pressure systems. Typically the semi-permanent high pressure over
the subtropical eastern Pacific blocks tropical cyclones from
leaving the deep tropics. They very often ride the trade winds and 
follow a WNW track after forming, moving into the open ocean. 
With the deep trough over the west coast breaking up the typical 
pattern, the door is open for this particular tropical cyclone to 
take a more northerly track, roughly parallel to the coast of 
Mexico.

To be clear, there is virtually no chance that a hurricane will
make landfall in California. While it's true the SST anomalies 
are quite high (3-5 F) along this track, the actual water 
temperature (70-74 F) is still far too cold to support a 
tropical cyclone north of the Vizcaino Peninsula (mid Baja). 
However, if the cut-off low stays strong enough, and moves far 
enough south to pull the tropical cyclone quickly to the north, 
there could be impacts from the remnants of this system in about a
week. The primary impacts would be rain and wind, and they would
likely be focused across Southern California. There are so many 
moving puzzle pieces that it's impossible to be more specific at 
this time, but the chance is there, and we'll keep an eye on it.

&&

.AVIATION...
(06Z TAFS)
Issued at 950 PM PDT Sun Aug 30 2026

VFR prevails except for nearly continuous stratus and fog/mist 
/MVFR-IFR/ along the immediate coast from Point Reyes southeastward.
The earlier steady erosion on the northwestern edge of stratus 
has paused while nocturnal radiative cooling is underway; it is 
dry to very dry above the marine layer. Additional coastal stratus,
fog/mist and drizzle will form including an inland intrusion 
tonight and Monday morning. Conditions improve to MVFR-VFR along 
the coastline Monday late morning and afternoon. Robust lower
level cool air advection will deepen the marine layer especially 
Monday through Monday night. Stratus and patchy drizzle redevelop
Monday night and early Tuesday.

Vicinity of SFO...VFR except stratus /MVFR/ ceiling 10z-18z Monday
then a stratus ceiling redevelops 04z Monday evening. West wind 8
to 15 knots.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Stratus /MVFR-IFR/ tonight and Monday 
morning. Tempo light drizzle KMRY 10z-14z, conditions improve to 
MVFR-VFR late Monday morning. Stratus /MVFR/ returns Monday evening.
West to northwest winds 5 to 15 knots.

&&

.MARINE...
(Tonight through next Saturday)
Issued at 934 PM PDT Sun Aug 30 2026

Fresh northwest winds diminish to a moderate breeze overnight,
allowing rough seas to subside to moderate by Monday morning. The
long period southerly swell continues to decrease tonight.
Northwest  to westerly winds remain gentle to moderate through the
remainder of  the work week as slight to moderate NW seas prevail.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 3 AM PDT Monday for Pt Arena to Pt 
     Reyes 0-10 nm.

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

&&

$$

SHORT TERM...Flynn
LONG TERM....Flynn
AVIATION...Canepa
MARINE...Canepa

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Prepared by Boulder-Creek.com Weather at: Mon Aug 31 02:30:03 PDT 2026