Area Forecast Discussion
Issued by NWS Sacramento, CA

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941
FXUS66 KSTO 181030
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
330 AM PDT Mon Sep 18 2017

.SYNOPSIS...
Cooler weather this week with a chance of showers by mid-week.

&&

.DISCUSSION...
Some mid and high clouds beginning to move into far northern
California early this morning ahead of the approaching front.
Elsewhere, skies are clear. Current temperatures range from the
lower 30s in the colder mountain valleys to the 60s to around 70
in the Central Valley.

Initial cold front moves south through the area today and is
expected to be mostly dry, though enough moistening of the airmass
may take place for some sprinkles or light showers across the
higher elevations of the northern Sierra Nevada into this evening.

A better chance of showers will be possible further south into
NorCal Tuesday night into Thursday as the trough deepens along
the West Coast and colder air drives further south. The best
chance of precipitation will remain over the mountains with even
some early season snow showers/flurries possible for the higher
peaks.

The most noticeable change in the weather this week will be the
trend toward cooler temperatures and breezier conditions.
Temperatures will start out the week around 5-10 degrees below
average, but will be about 10-20 degrees below average after mid-
week!

&&

.EXTENDED DISCUSSION (Friday THROUGH Monday)
Cool and unsettled pattern will continue fall-like weather on
Friday as a high amplitude trough pattern moves through the west
coast. Scattered rain showers and light snow for the highest
Sierra peaks are possible as the disturbance exits northern
California. High temperatures will range between 5 and 15 degrees
below normal.

Forecast models are fairly consistent with the strength and
progression of the system, and the upper trough which will begin
to exit for the weekend. Temperatures will warm to near to
slightly above normal by Sunday as a high pressure strengthens in
the eastern Pacific. Dry weather will ensue for the weekend.

&&

.AVIATION...
VFR conditions for valley terminals, except the chance for
occasional MVFR conditions in the northern Sac valley due to
smoke. Breezy conditions will develop this afternoon with gusts up
to 20 kts for the valley and up to 30 through the delta and for
Sierra ridgetops.

&&

.STO WATCHES/WARNINGS/ADVISORIES...None.

&&

$$



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