Weather Service Report

FXUS66 KSTO 222209

309 PM PDT Wed Oct 22 2014

A slow moving weather system will bring a roller coaster of
wet/dry/wet weather to end the work week into the weekend.
Thursday will see the first wave impact mainly the coastal range
and northern Sacramento valley. Dry and a rebound in temperatures
Friday with increasing south winds late Friday. Saturday through
Sunday will see widespread precipitation with breezy winds and
isolated thunderstorms Saturday. Saturday night will bring some
high elevation snow to northern Sierra, and lingering showers
Sunday. Next week will continue below average temperatures with periods of
precipitation in the north. 


Clouds are increasing across northern California as the first
weather system pushes inland. Most of the energy with this first
wave looks to be across the Northern Sacramento valley and
mountains, north of Interstate 80 during the day Thursday. Temperatures
will be just slightly below normal, expect San Joaquin valley
where temperatures will be near normal. As the parent weather
system digs late Thursday, a ridge will build overhead, essentially
drying things out and warming temperatures once again. Also, an
increasing pressure gradient will increase south winds late Friday
into Saturday. At this time, winds are not expected to be strong
enough for any headlines, but those with holiday decorations may
want to secure them, or move indoors. The main weather system will
move into northern California Saturday through Sunday. Saturday
looks like a good fetch of moisture will bring widespread rains to
a majority of the valley. Even the northern San Joaquin Valley
looks to also see some light rain amounts. Temperatures on
Saturday are expected to be below average. With the main trough
passage late Saturday and Saturday night, there is a slight chance
for some thunderstorms, mainly over the northern valley and
mountains. Also, snow levels are expected to lower to between
6500-7000 feet. Some light snow accumulations are also possible
overnight Saturday night.

The models show the main trough moving east of California Sunday,
but differ on the amount of precipitation that will linger with
its departure. Therefore continued a chance of showers, but showed
a decreasing south to north trend through the day. 

.Extended Discussion (Sunday through Wednesday)

There is some discrepancies in the models as far as the timing of
the trough exiting northern California Sunday/Sunday night.
Therefore, have lingered showers over northern California through
the day, then shifted to the northern mountains and lowered to
slight chance Sunday night. Monday through Wednesday, the models
show a progressive flow ushering in weak pacific weather systems
across northern California. However, the exact strength and timing
of each wave is uncertain. Therefore, after what looks like a dry
day on Monday, have continued a chance of precipitation Tuesday
and Wednesday. It does appear the best moisture/energy from each
wave will impact locations north of Interstate 80. Temperatures
will remain at to just below normal, with readings in the lower to
mid 70s. 



Increasing high and mid clouds as the cold front approaches, but
TAF sites should remain VFR through this evening. Generally light winds
for the Valley, around 10kt or less. Rain will gradually begin to
spread into the northern Sacramento Valley after 00z this
evening. KRDD and KRBL may have reduced visibilities during
showers after 12z, but expect those sites to hover between MVFR/VFR.
Light rain expected across much of our CWA between Thursday
morning into evening. JBB


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Western Regional Climate Center,