326
FXUS66 KMTR 170535
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1035 PM PDT Wed Apr 16 2025

...New AVIATION, MARINE...

.SYNOPSIS...
Issued at 304 AM PDT Wed Apr 16 2025

Cooler temperatures again today. Otherwise, dry weather is
expected through the forecast period. Warming trend begins
tomorrow and continues into the weekend. In terms of the isolated
thunderstorm threat for today, decreased chances to 10-14% which
removed that from the point and click. See details below.

&&

.UPDATE...
Issued at 730 PM PDT Wed Apr 16 2025

Satellite shows stratus over the northern half of the region with
mid-to-high level clouds entering the southern half of the region
from the east. Lightning activity is diminishing across the state
with the loss of daytime heating. The forecast remains on track
with no updates needed at this time.

Sarment

&&

.SHORT TERM...
Issued at 212 PM PDT Wed Apr 16 2025
(This evening through Thursday)

Cooler and cloudy conditions exist over San Francisco area and for
portions of the North Bay. There is some thinning of the clouds,
but a solid feed continues thanks to a week circulation west of Pt
Reyes. The broad picture shows some weak instability over the
forecast area in the way of afternoon cumulus build ups over the
hills. While the chances for thunderstorms have all but
disappeared convection is firing over the Sierra. Latest ACARS for
SFO and SJC show some MUCAPE, but it`s being crushed by bigger
CIN. Some of the better moisture/instability is forecast to brush
the Central Coast the next 12 hours, but still looking dry.

For tonight: some mid-high level clouds are expected to filter
over the region. Lower and at the surface, a robust marine layer
is expected once again with some variations on depth from N to S.
Similar to this morning actually, higher depth and cloud coverage
for northern areas and less to the south.

Thursday: clouds to start the day with a discontinuous marine
layer. The longwave pattern shows the cut-off upper level low that
has been spinning off the coast will move inland near LA as it
transitions to an open wave. As this happens, another wound up
upper low sweeps through the Great Basin. Locally, we`re looking
for a more dry northerly flow with a slight warming trend.

&&

.LONG TERM...
Issued at 212 PM PDT Wed Apr 16 2025
(Thursday night through next Tuesday)

To round out the work week and the start of the weekend we`ll see
a notable warming trend. The interior upper low in the Great
Basin will help establish a period of offshore flow Friday and
Saturday. While not overly strong, it`s enough to assist with
the warming trend due to downslope flow. High pressure also begins
to build over the PacNW and drift into CA. Despite this setup the
marine layer will compress, but may not completely go away.

The warmer weather will hold into early next with dry zonal flow.
Temperatures finally cool mid week with a weak trough developing
over the West Coast.

&&

.AVIATION...
(06Z TAFS)
Issued at 1033 PM PDT Wed Apr 16 2025

MVFR stratus extends across the North Bay, northern San Francisco
Bay, western San Mateo Peninsula, and southern Monterey County, and
will build across the coastal regions overnight. Low to moderate
confidence on clearing times Thursday morning, with some model
guidance holding onto the ceilings well into the afternoon and
evening. Opted to bring the clearing times a little later, aligning
with the model consensus. Breezy northwesterly winds will build
through Thursday afternoon. Thursday night into Friday, low to
moderate confidence on stratus extent and timing, with some  models
showing stratus development at significantly later times than those
reflected in the TAFs.

Vicinity of SFO... MVFR ceilings persist overnight and through late
Thursday morning. Moderate confidence on the timing of stratus
clearing with the models trending towards clearing later Thursday
morning or even early in the afternoon. Breezy west winds will
resume Thursday afternoon. Low confidence in the arrival time of
stratus at the terminal on Thursday evening, with some high
resolution models opting for stratus development relatively early
in the evening while others opt to develop the stratus after
midnight.

SFO Bridge Approach... Similar to SFO.

Monterey Bay Terminals... VFR through the next couple of hours
before MVFR stratus returns overnight through Thursday morning.
Ceilings might lift above MVFR criteria before the skies fully clear
out early Thursday afternoon, as breezy onshore winds return to the
region. Moderate confidence in an early return of stratus late
Thursday afternoon, with some models continuing to hold off the
stratus deck through the end of the TAF period.

&&

.MARINE...
(Tonight through next Tuesday)
Issued at 1033 PM PDT Wed Apr 16 2025

Moderate northerly winds dominate north of Point Reyes, but
southerly winds persist elsewhere. Near gale force gusts in the
northern outer waters will create hazardous conditions for small
craft overnight. Northerly winds will spread through the rest of
the waters through Thursday and gradually build into the weekend.
Rough seas persist in the northern outer waters through Thursday
morning. Otherwise, slight to moderate seas persist into the
weekend.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 3 PM PDT Thursday for Pt Arena to Pt
     Reyes 10-60 NM.

&&

$$

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

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