Portola Valley, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

145
FXUS66 KMTR 241135
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
335 AM PST Sat Jan 24 2026

...New AVIATION...

.KEY MESSAGES...
Updated at 326 AM PST Sat Jan 24 2026

 - Gusty offshore winds across higher terrain of the North Bay and
   East Bay through late tonight

 - Morning fog across some Bay Area Valleys, that clears in the
   mid morning

 - Potential weak storm system in the middle of the next work week

&&

.SHORT TERM...
Issued at 326 AM PST Sat Jan 24 2026
(Today and tonight)

Winds along the higher peaks in the North Bay became strong early on
into the night and these winds will begin to spread aloft across the
region further into the morning. Meanwhile, winds at the surface are
just about still, which has allowed formation of fog and low clouds.
The increased offshore flow aloft will introduce drier air through
the morning, with some of the surface moisture being chipped away as
the column of air mixes.

This will lead to quicker clearing of skies than previous days.
Short-term high-resolution models show a quick clearing of most of
the area by the mid morning as the dry flow continues to build in.
The clearer skies will allow for temperatures in lower elevations to
see high temperatures around 5 degrees or so warmer than yesterday
(widespread lower 60s). Winds in the higher elevations and aloft
will stay on the stronger side, but the potential for that wind to
make it into the lower elevations is poor.

Winds look to reduce into the night, but the dry air remains,
leading to clear skies, but cooler low temperatures. Sunday night
offers lows in the 40s and 50s along the coast, but upper 30s and
lower 40s for the more inland areas. The more interior areas could
see lows into the mid 30s, and a few localized spots in the lower
30s.

&&

.LONG TERM...
Issued at 326 AM PST Sat Jan 24 2026
(Sunday through Friday)

The offshore flow turns back to weak onshore flow further into
Sunday, but another ridge forms in the jet stream into late Monday
and Tuesday. Temperatures will see some light reductions and
increases through this quick change, but nothing extreme. This will
also make marine layer, low cloud, and fog forecasting interesting
into the next work week as the pressure falls and rises. Another
element to consider will be the return of high clouds Sunday and
into the work week, which could complicate overnight cooling and fog
development. Fun for our aviation forecasters!

The mid week forecast still is a matter of the GFS vs every other
model. The GFS has the ridge strengthen and places the approaching
cold front and low pressure well to the north, continuing our dry
trend. Other models just have the ridge push east as the front and
low move into the area, leading to widespread light rain chances
into Wednesday. The GFS output doesn`t look like a typical mid-
winter set up, so there is a lot of doubt there. The official
forecast leans on the ECMWF`s pattern, which would lead to light
rain early Wednesday through mid Thursday.

&&

.AVIATION...
(12Z TAFS)
Issued at 335 AM PST Sat Jan 24 2026

There are areas of stratus and fog /LIFR-MVFR/ however satellite
and surface observations also show partial clearing. Drier north
to northeast winds aloft will help mix out stratus and fog through
morning. VFR prevails later in the morning and afternoon. Dry weather
tonight and Sunday morning supports VFR as well.

Vicinity of SFO...Stratus/ MVFR/ until 1630z then VFR today, tonight
and Sunday morning. Mainly north to northeast wind 5 to 10 knots.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Stratus /MVFR until 17z then VFR today,
tonight and Sunday morning. Light and variable winds becoming
north to northwesterly 5 to 10 knots in the afternoon. Winds
southeasterly 5 to 10 knots tonight and Sunday morning.

&&

.MARINE...
(Today through Thursday)
Issued at 326 AM PST Sat Jan 24 2026

Moderate to fresh northerly breezes today and tonight. Wave
heights continue to subside today. Improving wind and sea
conditions will persist through the weekend to mid next week.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...None.
&&

$$

SHORT TERM...Murdock
LONG TERM....Murdock
AVIATION...Canepa
MARINE...Canepa

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