Scientific Forecaster Discussion
fxus66 kmtr 211203
Area forecast discussion
National Weather Service San Francisco Bay area
403 am PST Thu Nov 21 2019
Synopsis...gusty winds in the north and East Bay mountains will
decrease this morning. Dry conditions, along with seasonable
temperatures, are forecast today through the upcoming weekend.
Rain chances will develop by late Tuesday of next week and
possibly impact the Thanksgiving Holiday.
Discussion...as of 3:19 am PST Thursday...latest automated
observations indicate some gusty offshore winds are still
occurring in the north and East Bay hills with wind gusts
generally in the 30-40 mph range. However, relative humidity
values are over 30 percent in these breezier areas. After
coordinating with neighboring offices, the red flag warning has
been canceled. Satellite imagery reveals mostly clear skies,
except some low coastal stratus extending into Santa Cruz County,
and some higher clouds over portions of the the southern half of
Dry weather will continue through the rest of the work week and
through early next week. Overnight low temperatures are forecast
to cool into the 30s to mid 40s during the weekend, coolest in the
inland valleys. High temps will be mild, generally in the 60s.
A pattern shift is still looking probable next week. Models remain
in relatively good agreement in bringing a cool upper level
trough in from the northwest on Tuesday, with widespread rain
developing by late that day. Shower chances to persist through
midweek with the trough moving east by Friday.
Aviation...as of 4:05 am PST Thursday...low clouds from Southern
California are moving into the Big Sur coast and northern
Monterey Bay. Clouds are close enough to mry that there could be
scattered clouds this morning with the possibility of MVFR cigs. Clear
skies over the sfo Bay area but north to northeast winds 5-10 kt
will prevail through most of the day. Low level wind shear over
the North Bay and East Bay hills through 15z. MVFR ceilings
expected along the coastline later Thursday and Thursday night as
more clouds come up from the south.
Vicinity of ksfo...VFR. North to northeast winds 5-10 kt through
becoming light SW after 00z.
Sfo bridge approach...similar to ksfo.
Monterey Bay terminals...scattered clouds over mry through 18z with
possibility of brief MVFR cigs. East-southeast winds around 5 kt at mry and
5-10 kt in the Salinas valley. MVFR cigs expected Thursday
Fire weather....as of 3:17 am PST Thursday...gusty offshore
winds in the hills of the north and East Bay have subsided
overnight, but some gusts remain in the 30 to 40 mph range.
Relative humidity values remain over 30 percent, however, so the
red flag warning has been canceled.
Fire weather concerns will return early next week as medium range
models suggest another round of offshore flow impacting the
region and be potentially more widespread. Hot dry windy index
shows values increasing to nearly 400 by Monday. Stay tuned - fire
season is definitely not over until the region receives
widespread wetting rainfall.
Marine...as of 03:47 am PST Thursday...low pressure over Southern
California willmove slowly east. This will bring light east to
southeast winds through Friday. Winds will switch to north to
northwest late on Friday. A long-period northwest swell will
arrive by Saturday.
Public forecast: Sims
aviation: west pi
marine: west pi
fire weather: Sims/dykema
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