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

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FXUS66 KMTR 170625
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco Bay Area
1125 PM PDT Mon May 16 2022

.SYNOPSIS...A warming and drying trend will persist through
midweek and continue into the upcoming weekend. Breezy onshore
winds are also likely each afternoon and evening with the
potential for offshore winds to develop Thursday into Friday
across the interior.

&&

.DISCUSSION...as of 08:44 PM PDT Monday...After a cool and cloudy
start to the day skies did finally clear in the late afternoon.
As of sunset there is much less cloud cover than yesterday
evening during the eclipse. A passing upper level boundary and
drier air from the north will cut down on cloud cover tonight.
There will still be some stratus due to the persistent onshore
flow, but not a widespread stratus intrusion. Speaking of onshore
flow, yep it`s still happening. The SFO-SAC gradient peaked at
over 4 mb this afternoon resulting in another windy day around the
Bay Area and Central Coast. Max wind gusts since last night range
from around 20 mph to just shy of 50 mph. Coastal areas, higher
peaks, and inland gaps/passes were the windiest spots.

For more details of the upcoming forecast see below. However, a
few weather items of note that the midnight shift will be
assessing further will be...

Wind: Breezy to gusty wind will continue through much of the
upcoming week...some of it onshore and some of it
northerly/offshore. Onshore will continue through Tuesday. A much
stronger burst of winds will arrive Wednesday and moreso
Thursday. The ECMWF EFI has a nice bullseye off the SF coast on
Wednesday due to a strong N-S gradient. The EFI also shows another
broader area of strong winds on Thursday due to a passing inside
slider to the N. The Thursday winds will be more northerly and at
times offshore.

Fire Weather: A gradual drying trend will continue and bottom out
on Thursday. Given the potential for northerly and offshore flow
Wednesday into Thursday RH values will drop both day and night.
Hi-res WRF model shows low teens to near 10% during the day on
Thursday. Fuels aren`t fully in fire season yet, but they`re
getting there as evident by the recent grass/veg fires around the
Bay Area the last few days. Low humidity and gusty winds will
heighten fire weather concerns on Wednesday and Thursday.

Heat: Longer range model guidance shows a nice push of hot weather
with many 90s occuring across the interior.

&&

.PREV DISCUSSION...as of 01:51 PM PDT Monday...

Look for drying conditions aloft to limit the depth of the marine
layer tonight into Tuesday morning. As a result, look for less
inland intrusion of stratus tonight into Tuesday morning with
temperatures dropping into the 40s to lower 50s (near the
coast/bays). A warming trend is then likely from Tuesday into
Wednesday as high pressure over the Pacific builds across the
region. This will bring daytime temperatures back into the
mid/upper 70s to mid 80s on Tuesday with upper 80s to lower 90s by
Wednesday. Meanwhile, breezy to at times gusty onshore flow near
the coast will likely hold temperatures in the 60s to lower 70s
through midweek.

Very slight cooling is expected on Thursday as another mid/upper
level trough drops into the Pacific Northwest. However, the colder
air mass looks to remain well enough to our north and inland to
keep temperatures above seasonal averages through late week. The
main impact will be an increase in northerly winds on Thursday and
Friday along with drying conditions. As the mid/upper level
trough exits the Pacific Northwest and drops southeastward into
the Great Basin, winds may turn offshore across the interior`s
higher terrain. Depending on the strength and placement of this
"inside slider", we`ll have to monitor for increased fire weather
concerns late in the week.

High pressure over the eastern Pacific will then remain the
dominate weather feature heading into the upcoming weekend. As
such, look for inland areas to remain in the 80s to lower 90s
while upper 60s to 70s will be common closer to the coast/bays.
Dry conditions and above average temperatures look to persist into
the extended forecast period.

&&

.AVIATION...as of 11:25 PM PDT Monday...For the 06Z TAFs. VFR
except IFR-MVFR due to patchy coastal stratus. Breezy to gusty
onshore winds mostly from Tuesday afternoon to evening.

Vicinity of KSFO...VFR, breezy west wind except strong and gusty
again Tuesday afternoon and evening.

KSFO Bridge Approach...Similar to KSFO.

Monterey Bay...Patchy stratus /IFR-MVFR/ tonight and Tuesday morning
otherwise VFR. Breezy to gusty onshore winds Tuesday late morning
and afternoon.

&&

.MARINE...as of 11:13 PM PDT Monday...Strong northwest winds
tonight with near gale to gale force gusts developing across much
of the coastal waters. These strong winds will persist through the
week generating steep and hazardous seas at periods of 7 to 9
seconds. Even stronger northerly winds  expected late Thursday
into Friday.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .Tngt...SCA...Pt Reyes to Pigeon Pt 0-10 nm
             SCA...Pigeon Pt to Pt Pinos 0-10 nm
             SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm
             GLW...Pt Arena to Pt Reyes 0-10 nm
             GLW...Pt Pinos to Pt Piedras Blancas 0-10 nm
             GLW...Pt Arena to Pigeon Pt 10-60 nm
             SCA...Mry Bay
             SCA...SF Bay until 3 AM

&&

$$

PUBLIC FORECAST: MM/RGass
AVIATION: Canepa
MARINE: Lorber

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