Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Francisco Bay area
806 am PDT Sat Aug 23 2014
Synopsis...night and morning low clouds and slightly below
normal afternoon high temperatures are forecast through the
Monday. Warmer temperatures are likely inland by the middle of
Discussion...as of 08:00 am PDT Saturday... stratus has pushed
well inland this morning into the Napa Valley...tri-valley...and
southern Salinas valley. Clouds will clear back to the coast by
late morning today. Temperatures will be a degree or two warmer
inland but otherwise substantially similar to yesterday. Forecast
is on track for similar conditions to continue through Monday
before a warm up inland due to a building upper ridge. No major
updates are anticipated this morning.
Previous discussion...as of 3:30 am PDT Saturday...an upper level trough
is currently over the Great Basin. The marine layer is near 2000
feet per sodars and stratus extends well inland this morning. This
upper trough will move east today but weak upper level troffing
will linger over the Great Basin Saturday and Sunday. A more
potent shortwave will move through the Great Basin on Monday.
After this system moves east an upper level high will move in over
the West Coast from the eastern Pacific. Temperatures will
continue to run near or slightly below normal through Monday then
significant warming for Tuesday and Wednesday.
Models indicate the marine layer will not be mixed out by the
passing troughs so the night and morning low clouds will persist.
Local coastal drizzle cannot be ruled out. The marine layer will
compress from Tuesday on and be more confined near the coast.
By the end of the week this upper ridge gets pushed east as an
upper trough approaches the Pacific northwest. A few of the GFS
ensemble members show this upper trough picking up moisture from
Hurricane Marie and bringing rain to northern California. However
the European model (ecmwf) and Canadian models remain dry. Since the general
consensus of the models lean towards no rain...the extended
forecast which GOES out to next Saturday remains dry.
Aviation...as of 4:35 am PDT Saturday...the marine layer is
approximately 2000 feet deep this morning with stratus apparent
well inland. Satellite products are showing a nice hole in the
stratus positioned around ksfo this morning. Although there are
subtle differences in the current weather pattern burn off times
should be similar to yesterday.
Vicinity of ksfo...VFR should prevail this morning with MVFR ceilings
around the sf Bay area. There is a possibility that these ceilings
will pass over the approach between 1400 and 1600z this morning.
Westerly winds will increase to 10 to 15 knots this afternoon with
the sea breeze.
Confidence is moderate.
Ksfo bridge approach...similar to ksfo.
Monterey Bay area terminals...IFR ceilings are expected to prevail at
kmry this morning with MVFR at ksns. VFR is anticipated around
1700z at kmry and 1800z at ksns. Westerly winds will reach 10 to
15 knots with the afternoon sea breeze.
Confidence is moderate.
Marine...as of 04:26 am PDT Saturday...a weak surface pressure
gradient will maintain generally light to moderate winds across
the coastal waters through much of the forecast period. The
strongest winds are expected over the northern waters. A mixed
swell featuring a moderate period southerly component will
continue into early next week.
... Bay north of the Bay Bridge from 2 PM
Public forecast: ac/west pi
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