Area Forecast Discussion
Issued by NWS Sacramento, CA

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000
FXUS66 KSTO 191910
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
1110 AM PST Fri Jan 19 2018

.Synopsis...
Showers and a few thunderstorms will taper off across the region
by this evening. The active weather pattern will continue with
another system expected to affect the region early next week.

&&

.Discussion...
Satellite and radar show the main band of precipitation has
shifted to the south and east, with much of the Valley clearing. Some
light showers continue around Yosemite National Park southward.
Some additional shower activity is developing over the Coastal
Range, with instability in cold air aloft. This convective
activity is expected to increase further this afternoon, with some
scattered rain showers and some isolated thunderstorms developing
in the Valley and foothills.

Snow showers could locally produce another 1-4" of snow in the
mountains, though this will be very much a `hit and miss`
situation. Snow levels are currently around 3500 feet.Heavy snow
showers could also bring a brief period of whiteout conditions and
rapidly accumulating snow, so motorists are urged to use caution
driving this afternoon. Will continue Winter Storm Warning and
Advisories for now (Through 4 PM), due to the local shower threat. EK

&&
.EXTENDED DISCUSSION (Tuesday THROUGH Friday)

Unsettled pattern will continue through the extended period.
Moisture is expected to spread across interior NorCal on Tuesday
and impact the area through Thursday as troughing in the Gulf of
Alaska dives southward. However, forecast guidance is still
struggling with the overall progression of the system. Early QPF
estimates suggest 0.5-1" in the Valley, and 1-2" over the
mountains through early Thursday with the potential for
accumulating snow over the mountains. Drier weather is expected by
Friday afternoon as the trough axis shifts eastward, although
lingering activity could persist over the mountains.


&&

.AVIATION...

Precipitation continues early this morning bringing IFR/MVFR
ceilings and visibility over the mountains. Improving conditions
after 00z Saturday, generally MVFR occasional IFR in showers.
Otherwise, VFR conditions and light winds across TAF sites.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning until 4 PM PST this afternoon for West
Slope Northern Sierra Nevada-Western Plumas County/Lassen Park.

Winter Weather Advisory until 4 PM PST this afternoon for
Mountains Southwestern Shasta County to Northern Lake County-
Shasta Lake Area / Northern Shasta County.

&&

$$



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