Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Francisco Bay area
1005 PM PST Thursday Feb 26 2015
Synopsis...a storm system will bring showers and cooler
temperatures to the area tomorrow through the weekend. Another
weak system will bring additional shower chances to the area on
Discussion...as of 9:00 PM PST Thursday...surface high pressure
over the eastern Pacific extending into Oregon brought a drier
northerly flow to the area today. As a result temperatures were a
couple of degrees warmer than yesterday.
An upper low over Vancouver Island continues moving south. This
low will usher in colder air aloft over the area destabilizing
the atmosphere which will bring a slight chance of showers Friday.
Northwest winds will also pick up Friday ahead of the system especially
along the coast. The low will move into northern California Friday
night and into our County Warning Area Saturday increasing shower chances. Part of
the system moves over the ocean Saturday and will add a little
extra moisture for the southern part of the County Warning Area. As a result the
highest probability of precipitation will be from the Santa Cruz Mountains south. There is
a slight chance of thunderstorms in these same areas but cannot
rule the possibility of a thunderstorm in the sfo Bay area.
Shower chances decrease Saturday night as the low moves into
Southern California. By this time snow levels will lower to 4000
feet so if there are any showers left by then there could be a
dusting of snow on the highest mountains. Total rainfall amounts
will be light ranging from less than one-tenth of an inch in the
northern County Warning Area and up to one-quarter inch in the south. Amounts
could be higher along the Santa Cruz and Monterey County coast and
mountains where over one-half inch is possible in locally
Partly cloudy and cool conditions for Sunday before a second
system drops down from the north. This will bring another chance
of showers to the area Monday or Monday night with continued cool
temperatures. Latest models show less moisture with this system
as it is tracking a little further inland so any rainfall amounts
will only be less than one-tenth of an inch.
Upper level ridge will build back into our area by the middle of
next week leading to dry conditions with above normal temperatures
into next weekend.
Aviation...as of 9:50 PM PST Thursday...for 06z tafs. Locally
gusty winds will continue as a strong northerly gradient persists
across area terminals through late tonight. The strong gradient
will also keep terminals free of low clouds with some high clouds
expected to stream in from the north. Models are hinting of patchy
low level clouds developing ahead of the next system late tonight
into Friday. Winds will ease a bit overnight with strong and gusty
winds expected once again Friday afternoon. Moderate to high
Vicinity of ksfo...VFR with mostly clear skies through late tonight.
Gusty west winds expected through late tonight for ksfo with gusts to
26 knots forecast.
Ksfo bridge approach...similar to ksfo.
Monterey Bay area terminals..VFR with mostly clear skies through
late tonight. Gusty northwest winds down the Salinas valley.
Marine...as of 8:57 PM PST Thursday...strong and gusty northerly
winds and rough seas will continue overnight into Friday as a
weather system drops down from the north. The chance of showers
will increase through Friday beginning over the northern waters
and spreading south. Shower chances will linger into Saturday
before winds finally subside as the weather system moves inland.
Lighter winds return Sunday but large seas will continue through
... Pt to pt pinos 0-10 nm
Small Craft Advisory...pt Arena to pt Reyes 10-60 nm
Small Craft Advisory...pt Reyes to Pigeon pt 10-60 nm
Small Craft Advisory...Pigeon pt to pt pinos 10-60 nm
Small Craft Advisory...pt pinos to pt Piedras Blancas 10-60 nm
Small Craft Advisory...pt Arena to pt Reyes 0-10 nm
Small Craft Advisory...pt Reyes to Pigeon pt 0-10 nm
Small Craft Advisory...pt pinos to pt Piedras Blancas 0-10 nm
Public forecast: west pi
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