Scientific Forecaster Discussion

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Area forecast discussion 
National Weather Service San Francisco Bay area
1045 PM PDT Thursday Apr 17 2014

Synopsis...dry conditions will continue through the weekend.
Moderate onshore flow will maintain cool conditions near the
coast...along with areas of night and morning low clouds and fog.
Temperatures for inland areas will mostly remain a little warmer
than normal. A low pressure system will arrive late Monday and
Tuesday...bringing a chance of showers as well as cooler
temperatures through Wednesday.

&&

Discussion...as of 8:35 PM PDT Thursday...an upper level trough
and associated cold front are currently moving through the Pacific northwest
and northern California. Isolated thunderstorms have developed
along the front this evening across far northern California...but
the front is dry at our latitude. This system has produced enough
cooling aloft and low level mixing across our area to mostly mix
out marine layer clouds this evening. Expect areas of low clouds
to develop near the coast late tonight as northwest winds begin
to ease.

Cooling occurred across most of our area today...but temperatures
are expected to rebound slightly beginning tomorrow as shortwave
ridging develops aloft. A shortwave trough will move into the Pacific
northwest on Saturday...but this trough is expected to be too far north
to have an impact on our weather. In fact...very little change is
expected from Friday through Sunday. Daytime temperatures will be
slightly above normal inland and near normal to slightly below
normal at the coast where moderate onshore flow will persist.
Areas of night and morning low clouds will continue...but clouds
will mostly be confined to coastal areas.

Onshore flow will strengthen on Monday as an upper level trough
approaches the West Coast. Temperatures will begin to cool on
Monday and then drop several degrees below normal on Tuesday and
Wednesday as the upper trough moves inland. Shower chances will
begin Monday evening and continue through Wednesday morning...with
the best chance of measurable rainfall expected late Monday night
and Tuesday morning. There may be enough instability on Tuesday
for isolated thunderstorms to develop...mainly across the
northern part of our area. This system will not have a great deal
of moisture with it and rainfall amounts from late Monday through
early Wednesday are expected to be light...generally less than a
tenth of an inch. Dry conditions should return to most areas by
Wednesday afternoon. The medium range models then indicate a
potentially stronger and wetter system arriving by the last
weekend in April.

&&

Aviation...as of 10:45 PM PDT Thursday...mostly clear skies are
being reported across the forecast area this evening. The current
infrared satellite image is showing a middle level cold front passing by
which is aiding in mixing out the low clouds. The Fort Ord
profiler is still indicating a deep marine layer. Therefore it is
a real possibility that stratus will return to at least Monterey
and Salinas overnight.

Vicinity of ksfo...VFR is expected to prevail overnight with a
possibility of ceilings broken-ovc010 between 1200 and 1600z.

Confidence is moderate

Ksfo bridge approach...similar to ksfo.

Monterey Bay area terminals...VFR is expected to give way to
ovc007 by around 1000z.

Confidence is moderate

&&

Mtr watches/warnings/advisories...
... Arena to pt Reyes 0-10 nm
Small Craft Advisory...pt Reyes to Pigeon pt 0-10 nm
Small Craft Advisory...Pigeon pt to pt pinos 0-10 nm
Small Craft Advisory...pt pinos to pt Piedras Blancas 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

&&

$$

Public forecast: dykema
aviation: Larry

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