Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 220013
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
413 PM PST Wed Feb 21 2018

.SYNOPSIS...
A cold system will bring low elevation snow to the mountains
late tonight into early Friday, which could impact travelers.
Below normal temperatures will continue. Additional systems
possible next week.
&&

.DISCUSSION...
A cold system dropping south from western Canada will bring low
elevation snow to NorCal Late tonight into Thursday night. Snow
levels will be around 2000 feet, but briefly fall to 1000 feet at
times in heavier snow showers. The system has slowed a bit and
have pushed back the start time for the winter weather advisory to
after midnight. Snow amounts of 3 to 6 inches are expected above
2000 feet with local amounts up to 10 inches over higher peaks.
Foothill locations like Grass Valley...Placerville and Sonora can
expect 2 to 4 inches. Locations like Auburn and Jackson could even
pick up a quick dusting.

Unstable air will move over the area Thursday afternoon with
thunderstorms possible over the valley some with small hail. This
convective activity will also enhance snow as it moves into the
foothills and mountains late in the afternoon. The system will
move east of the area Thursday night with snow ending around
midnight.

A brief period of dry weather is expected Friday as short wave
ridge moves overhead between systems. The next system will drop
south in the northwest flow Saturday with a quick 1 to 3 inches
of snow for the Sierra north of highway 50.
&&

.EXTENDED DISCUSSION (Sunday THROUGH Wednesday)
Active pattern is expected through the extended period as
successive disturbances embedded in the upper flow drop down from
the north. Guidance is still struggling with the progression of
these systems and precipitation amounts. Regardless, these systems
have the potential to bring widespread precipitation, mountain
snow, and breezy to gusty winds. Given the cold nature of these
systems, snow levels will remain relatively low.

Unlike previous systems, the upcoming ones have the potential to
pull in significant moisture. At this point, Sunday appears to be
dry except for shower activity over the mountains. More widespread
precipitation is possible across the forecast area Monday into
early Tuesday. After a brief break late Tuesday into early
Thursday, a stronger and wetter system is progged to push across
interior NorCal late next week, but details remain uncertain.
Temperatures will remain at or below average.

&&

.AVIATION...
VFR conditions this evening. MVFR/IFR due to snow showers over
the foothills/mountains, mainly after 08z Thursday. Isolated
thunderstorms in the Central Valley after 18z Thursday.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 1 AM to 10 PM PST Thursday for
Burney Basin / Eastern Shasta County-Motherlode-Northeast
Foothills/Sacramento Valley-West Slope Northern Sierra Nevada-
Western Plumas County/Lassen Park.

&&

$$


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