Area Forecast Discussion
Issued by NWS San Francisco Bay Area, CA

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FXUS66 KMTR 160331

Area Forecast Discussion
National Weather Service San Francisco Bay Area
831 PM PDT Sat May 15 2021

.SYNOPSIS...Remaining cloudy near the coast but mostly clear
inland this afternoon. Also, there is a slight chance of showers
and thunderstorms across the far north today. Cooler than normal
temperatures are forecast this weekend. Slight warming is likely
early next week before temperatures cool below normal once again
during the second half of next week.

&& of 08:31 PM PDT Saturday...Convection from
from late this afternoon remained confined to our north with radar
and lightning detection showing some impressive looking thunderstorms
over Lake/Mendocino counties. Drier conditions around the Greater
Bay Area today aside from some patchy marine drizzle along the
coast. The marine layer remains deep as satellite imagery shows
stratus over the waters and along the coast. Expect night and
morning low clouds to move inland once again tonight and into
Sunday thanks to an upper low currently situated over California.
This will also keep high temperatures at or below seasonal
normals for Sunday afternoon. Highs across the region today were
in the mid 50s to low 60s along the coast and upper 60s to low 70s
inland. Similar forecast for tomorrow, though some locations may
be a few degrees warmer depending on how long stratus sticks
around for. No updates needed to the forecast this evening, for
additional details please see the previous discussion below.


.PREV of 02:09 PM PDT Saturday...Satellite
imagery reveals stratus lingering around SF and Monterey Bay with
a strong onshore push. Coastal areas may only see peaks of
sunlight today, aside from North Bay, where clearing is evident.
Still a slight chance of showers and T-storms in the northern
reaches of our CWA, as the upper low over CA may wrap around some
convective activity firing over the Sierra. Some hi-res models
support this scenario. Cool temps around the CWA, with 50s and 60s
prevailing. Inland areas where skies have cleared will likely
reach the 70s.

Tonight, low clouds push far inland again, but there will be
minimal showery activity. Patchy fog and coastal drizzle are
likely, however. The upper low overhead will drift slowly south
and east overnight. Not much change temperature-wise tomorrow,
perhaps a few degrees of warming as clouds look to retreat to the
coast more quickly. Coastal areas may be lucky enough to see some
sunshine as well. Marine layer will likely compress Sunday evening
as some weak ridging builds in from the Pacific.

Gradual warming will follow Monday and Tuesday, with temps
nearing normal. A deep trough approaches the PacNW wednesday,
supplying more cool air. There looks to be a rather potent low
associated with this trough, bringing the potential for rain
showers to northern parts of the CWA Thursday. Not much support
for any significant rainfall from deterministic models or ensemble
members. Models have been trending cooler towards the end of the
week. Stay tuned.


.AVIATION...As of 5:50 PM PDT Saturday...For the 00z TAFs. The
afternoon saw clearing skies in the east bay but marine stratus
remained at the coast. into the evening, low clouds will filter
into the SF Bay and push inland overnight. Expect mild winds and
MVFR conditions through the night as ceilings range from 1000 to
2200 ft AGL. Cloud cover begins to lift and thin for going into
late Sunday morning and into that afternoon, marking a return to
VFR conditions for most locations.

Vicinity of KSFO...Expect returning stratus with broken ceilings
falling to MVFR overnight. Winds will become light and variable
through the night. Westerly winds around 10 kts will pick up
Sunday morning and cloud cover will begin to thin and lift around
18 to 19z. Expect a return to VFR conditions for the afternoon,
before low clouds return that evening.

SFO Bridge Approach...Similar to KSFO.

Monterey Bay Terminals...Expect MVFR conditions through the night
with light and variable winds. Ceilings will lower to around 1500
ft AGL in the late night. Cloud cover remains through the
morning, with some clearing into the afternoon, allowing for VFR
conditions. Breezy and gusty westerly winds build in afternoon at
around 15 kts.

&& of 08:01 PM PDT Saturday...Locally breezy northwest
winds will persist over the northern outer waters into tomorrow
with light to moderate winds elsewhere. Winds will increase across
the waters by Monday afternoon and into Tuesday as a weather
system approaches from the Gulf of Alaska. Mixed seas will
continue with a moderate northwest swell and a lighter southerly


     .Tngt...SCA...Pt Arena to Pigeon Pt 10-60 nm




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