Foster City, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

708
FXUS66 KMTR 140643
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1143 PM PDT Tue May 13 2025

...New AVIATION, MARINE...

.SYNOPSIS...
Issued at 128 PM PDT Tue May 13 2025

Isolated showers possible this afternoon and evening across the
higher elevations of the interior North Bay, South Bay and Central
Coast. Gradual warming trend into Friday with cooling and gusty
winds for the upcoming weekend.

&&

.UPDATE...
Issued at 817 PM PDT Tue May 13 2025

Evening satellite looked like popcorn city with widespread cu
popping over the higher terrain of the Bay Area and Central
Coast. In fact, enough moisture, combined with weak instability
and daytime heating led to a few isolated showers. More widespread
shower activity developed well to the east over the Sierra. Now
that we`ve begun to lose daytime heating, cu and shower activity
are fading fast. We`ll keep radar in precip mode for another hour
or two, but then surveillance mode seems like a good path.

Similar to the last few evenings it`s breezy out there. See gusts
along the coast, gaps, and passes in the 20-30 mph range with a
few up to 40 mph. Winds will ease overnight for most areas, but
not go completely calm.

No update need this evening.

A few things we`ll be watch the next few days: warming up, drying
out, and bursts of northerly winds.

MM

&&

.SHORT TERM...
(This evening through Wednesday)
Issued at 128 PM PDT Tue May 13 2025

Satellite imagery generally shows fair weather cumulus clouds
popping up across the region in the wake of yesterday`s frontal
system. Further convective activity is possible through the day with
the greatest risk for showers across the interior mountains of
Sonoma and Napa Counties, the eastern Santa Clara Hills, and the
Gabilan range, but the probabilities are low (10-20%) and measurable
accumulations will be few and far between. Looking back to the
ingredients for convection (instability, moisture, and lift): there
is some decent instability from the cold upper level low that went
through, with surface-based CAPE up to around 600 J/kg in the
interior. Lift can be provided via our numerous mountain ranges, but
it`s the moisture that`s lacking. While our 12Z radiosonde launch at
OAK did not go up due to technical reasons, we were able to launch a
balloon at 15Z, which revealed a precipitable water value of 0.61
inches, around the average for this time of year. In addition, the
sounding reported a dry mid-layer, with a 700 mb dewpoint around -20
deg C and a 500 mb dewpoint of around -40 deg C. For context, in
terms of the averages for this time of year, those would place this
sounding around the driest 25th percentile for the 700 mb dewpoint,
and the driest 10th percentile for the 500 mb dewpoint. Any chance
for convective showers will disappear this evening as daytime
heating diminishes, and tomorrow should be dry.

High temperatures today range from the upper 60s to lower 70s across
the inland valleys, to the middle to upper 60s along San Francisco
Bay, and the upper 50s to the lower 60s at the Pacific coast. Highs
will warm up for the inland regions tomorrow as upper level ridging
builds across the West Coast, with middle to upper 70s in the inland
valleys and the upper 60s to lower 70s along San Francisco Bay.

&&

.LONG TERM...
(Wednesday night through next Monday)
Issued at 128 PM PDT Tue May 13 2025

The upper level ridge will support warming temperatures through the
rest of the work week with the inland valleys reaching the upper 70s
to middle 80s on Friday, while the Bayshore sees highs in the upper
60s to middle 70s. Highs along the coastal regions remain relatively
constant and cool, owing to the sea breeze influence.

An upper level trough will develop off the Pacific Northwest and
deepen into a cutoff low in the Great Basin, causing a dip in
temperatures for the upcoming weekend. Although the cutoff low will
continue to move eastwards, leaving a classic "inside slider"
scenario less likely, the pressure gradient between the cutoff low
and a ridge in the eastern Pacific will still result in gusty winds
across the region later on Friday into Sunday. The current forecast
shows wind gusts reaching 25 to 30 mph across the region with gusts
up to 40 mph possible at the ridgelines, along the coast, and
through favored gaps and passes. However, these are quite early
estimates, and as the event draws closer we`ll be able to leverage
additional high-resolution model data to better refine the forecast
and the areas with the greatest wind speeds. Stay tuned to the
forecast updates over the next few days.

&&

.AVIATION...
(06Z TAFS)
Issued at 1142 PM PDT Tue May 13 2025

MVFR CIGs are building along the coast and around the Monterey Bay
with winds reducing and becoming mostly light. Cloud cover begins to
filter into the SF BAY later into the night with OAK filling by the
early morning. CIGs erode in the mid to late morning, leading to
widespread VFR for the afternoon as winds become moderate to breezy.
Expect winds to reduce into the evening and early night. MVFR and
IFR CIGs build along the coast into Wednesday night, affecting HAF
and the Monterey Bay terminals.


Vicinity of SFO...MVFR CIGs begin to erode in the mid morning.
Expect winds to reduce into the the late night and become light for
the late morning as CIGs erode. Moderate west winds build in the mid
afternoon but become light again into Tuesday night.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...MVFR CIGS are building around the Monterey
Bay and look to fall to IFR later into the night for MRY. Expect
mostly light winds through the night. CIGs scatter into the mid to
late morning as moderate to breezy winds build. Winds reduce into
Wednesday evening as MVFR and IFR CIGs return.


&&

.MARINE...
(Tonight through next Monday)
Issued at 1142 PM PDT Tue May 13 2025

High pressure to north and low pressure to the south will keep
moderate to strong northwesterly flow over the coastal waters.
Gales are expected Tuesday night into Wednesday. These strong
winds will result in steep fresh swell with hazardous conditions.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 3 PM to 9 PM PDT Wednesday for Mry Bay.

     Gale Warning until 3 AM PDT Thursday for Pt Arena to Pt Reyes 0-
     10 nm-Pt Arena to Pt Reyes 10-60 NM.

     Gale Warning until 3 AM PDT Wednesday for Pt Reyes to Pigeon Pt
     0-10 nm.

     Gale Warning from 3 PM Wednesday to 3 AM PDT Thursday for Pigeon
     Pt to Pt Pinos 10-60 NM-Pt Reyes to Pigeon Pt 0-10 nm.

     Small Craft Advisory until 3 AM PDT Wednesday for Pigeon Pt to
     Pt Pinos 0-10 nm.

     Small Craft Advisory from 3 PM Wednesday to 3 AM PDT Thursday
     for Pigeon Pt to Pt Pinos 0-10 nm.

     Small Craft Advisory until 3 AM PDT Thursday for Pt Pinos to Pt
     Piedras Blancas 0-10 nm.

     Small Craft Advisory until 3 PM PDT Wednesday for Pigeon Pt to
     Pt Pinos 10-60 NM.

&&

$$

SHORT TERM...DialH
LONG TERM....DialH
AVIATION...Murdock
MARINE...MM

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