Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Francisco Bay area
1049 PM PDT Friday Jul 3 2015
Synopsis...outside of some coastal drizzle dry weather is
forecast through next week. A stronger marine influence will
return through the weekend with temperatures near or slightly
below seasonal averages through early next week.
Discussion...as of 8:34 PM PDT Friday...temperatures finished
off the day with 60s and 70s along the coast...70s and 80s around
the Bay and 80s and 90s over inland areas. A few 100s were
sprinkled around the southern portion of the forecast area over
the warmest inland areas. Overall temperatures stayed within a few
degrees of yesterdays high in most locations. Some areas cooled a
handful of degrees in response to either some increased cloud
cover or the return of westerly onshore flow. A few areas that
were either sheltered from the marine influence or received more
sunshine than the day before felt temperatures warm as much as
The return of westerly flow and a 2000 feet marine layer along the
coast is anticipated to allow for a stronger inland push of the
stratus tonight. Overnight temperatures will be mild in the 50s
and 60s across the district with patchy fog by morning.
Night and morning low clouds and fog and a gradual cooling trend
is in store through the Holiday weekend and through the first half
of next week as a stationary upper level low located off the
California coast approaches ever so slowly from the west. The low
will gradually deepen the marine layer as it nears and will
introduce a slightly cooler airmass that will culminate in below
normal temperatures over inland areas. Models do not indicate there will
be much moisture associated with this system and hence we do not
anticipate any showers. However drizzle along the coast is
possible as the marine layer deepens. Showers associated with this
system are expected to stay north and east of the warning area.
Forecast remains on track...no updates at this time.
Aviation...as of 10:50 PM PDT Friday... marine layer has been
deepening since late Friday afternoon and is currently 2000 feet
deep at Fort Ord. Also...onshore pressure gradients are
increasing. These factors will result in more widespread inland
development of low ceilings overnight...and will keep IFR/MVFR ceilings in
place somewhat later on Saturday morning compared to recent days.
Light to moderate onshore winds will continue.
Vicinity of ksfo...VFR through about 08z with MVFR/IFR ceilings
thereafter until 17z Saturday. Medium confidence. Light west winds
increasing to about 18 knots by late Saturday afternoon.
Sfo bridge approach... similar to ksfo.
Monterey Bay area terminals... IFR/LIFR ceilings overnight and into
Saturday morning...with possible visibilities reductions between 12-16z
Saturday. Light onshore winds.
Marine...as of 9:00 PM PDT Friday...a weak low pressure system
will linger over the coastal waters through the weekend and into
early next week...resulting in several days of generally light
winds and gentle seas over the coastal waters. Locally stronger
seabreeze winds are forecast for San Francisco Bay.
Public forecast: CW
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