Weather Service Report

FXUS66 KSTO 270455

Area Forecast Discussion
National Weather Service Sacramento CA
955 PM PDT Wed Oct 26 2016

Wet and unsettled weather Thursday into early next week as
several weather systems move across the area.


Some high clouds drifting through the region tonight ahead of the
next system. Some rain may start to arrive late tonight along the
coastal range and locally into the west end of the valley before
spreading over the area during the morning and afternoon hours.

Moisture from Hurricane Seymour will merge with the low off the
coast and spread over the area with the rain becoming heavy at
times Thursday night and Friday morning. The low will move east of
the region Friday afternoon with lingering showers over the
region. the heaviest precipitation with this first wave will be
over the southern two thirds of the forecast area south of Chico
in the valley and south of Shasta County in the mountains.
Snow levels will be very high and a non factor with this system.
Winds will not be that strong as well.

By Saturday morning another weather system will be moving over
parts of the interior and continuing to spread south and east
over the region throughout the day. Snow levels will continue to
be high during the day but closer to major pass levels over the
Sierra Nevada. Saturday night is when heavier rain starts to move
over the region and snow levels look like the may fall below major
pass levels. Timing of when that occurs depends on which model
turns out to be right with NAM indicating in the evening and GFS
later at night.


An active weather pattern is in store through our extended period
with yet another system moving in early Sunday. This storm is
expected to be a bit different as the main trough will be
dropping out of the gulf of Alaska and will bring some cooler air
with it. At this point, it looks as though snow levels could drop
down to 6500 feet on Sunday as the precipitation begins to taper

Early Monday, heights build as a weak transient ridge moves over
California between two troughs. Despite this, the ECMWF has enough
moisture to keep the shower activity going in the valley and
mountains while the GFS drys us out. Because of this, we have kept
showers in the forecast on Monday although most places could see a
break for trick or treating. However, this all depends on the
speed at which the next trough tracks into our area. Currently,
our next batch of rain looks to move into the valley Monday night
after 10 pm, although, given how far out this is, timing could
certainly change.

The global models suggests that even another system could move in
behind this although there are major differences in timing and
strength. At this point, we expect below normal temperatures with
the possibility of continued wet weather. Wilson


VFR conditions are expected through early Thursday morning before
our next system moves in. Cloud decks around 10 kft will move in
tonight and lower to around 3 kft as rain begins Thursday morning.
MVFR conditions expected for Thursday with IFR conditions expected
in heavier showers. Winds will be relatively light across all
valley terminals on Thursday. Wilson




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