Area Forecast Discussion
Issued by NWS Sacramento, CA

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387
FXUS66 KSTO 190517
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
917 PM PST Wed Jan 18 2017


.Synopsis...
A series of winter storms will move through NorCal through
Monday. Mountain travel impacts are likely due to snow and winds.
Moderate to heavy rain at the lower elevations with windy
conditions.

&&
.Discussion...
The strongest will spread through the central valley this evening
between 5 and 8 pm. Winds will continue to gradually decrease this
evening. Numerous reports of power outages and trees downed
during this time frame. Rain continues to spread inland with the
back edge of the front approaching Sacramento at 9 pm. Behind the
front showers are expected to develop through Thursday. Some of
the showers may be locally heavy at times during the day. Snow
will continue in the mountains and with the next system coming in
Thursday night there will not be much of a let up. Mainly a
tapering in intensity late tonight and Thursday morning before
snowfall begins to increase in intensity again.

.Previous Discussion...
First Pacific storm system in a series currently impacting NorCal
with rain and wind is bit faster than earlier forecast. Deep
moisture plume 1.5-2.0 inch precipitable water is passing over
northern California. Rainfall amounts generally from 1-2 inches
for the valleys through Thursday. The biggest impact with this
system will valley winds gusts to 50 mph which may cause downed
trees and power outages and heavy mountain snow with 1 to 2 feet
above 4500 feet. This will cause significant travel delays over
the mountains above 4000 feet. Snow could briefly fall all the way
down to 3000 feet in heavy precip bands. Small streams will begin
to rise overnight with minor flooding possible. Valley rain will
become more showery after midnight with a brief break possible
Thursday morning.

Showers and isolated thunderstorms will develop by late morning
Thursday and continue through the evening. A few strong storms may
be possible with some storm organization as a favorable shear
profile develops.

The next storm system will swing through NorCal Friday morning
into early Saturday with Valley rainfall of 1 to 2 inches and
mountain snow of 1 to 2 feet and snow levels 3000-4000 feet.
Another round of gusty winds with speeds to 40 mph will also be
possible.

&&

.EXTENDED DISCUSSION (Sunday THROUGH Wednesday)

Precipitation spreads across the entire forecast area Saturday
night into Sunday as next Pacific frontal system impacts interior
NorCal. Models have trended down some on QPF and now suggesting
upwards of 1 to 2.5 inches in the Central Valley and foothills
and upwards of 3 to 4 inches in wetter mountain locations. Snow
possible down into the foothills with this system and several feet
of new snow expected at pass levels impacting travel. Strong
southerly winds forecast Sunday and wind advisories may be issued
for portions of Interior NorCal. Decreasing showers Monday into Tuesday
as high pressure returns to the forecast area.
&&

.AVIATION...

Pacific storm system moving through the region bringing widespread
MVFR/IFR conditions across the Valley, and LIFR conditions over
the mountains. These conditions will likely continue through
Thursday morning. SE winds 20-30 kt with gusts to 45 kt will
decrease to 10-20 kt overnight tonight into Thursday.

Dang

&&

.STO WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning until noon PST Thursday for West Slope
Northern Sierra Nevada-Western Plumas County/Lassen Park.

Wind Advisory until midnight PST tonight for Carquinez Strait
and Delta-Central Sacramento Valley-Motherlode-Northern San
Joaquin Valley-Southern Sacramento Valley.

Winter Weather Advisory until 4 AM PST Thursday for Burney Basin
/ Eastern Shasta County-Shasta Lake Area / Northern Shasta
County.

&&

$$



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