Area Forecast Discussion
Issued by NWS Sacramento, CA

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135
FXUS66 KSTO 191253
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
453 AM PST Thu Jan 19 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...
Upper trough moving through norcal this morning producing
numerous showers. Most intense showers now occurring from the
Sacramento area northeastward into the foothills with isolated
thunderstorms. Some of these thunderstorms may have become briefly
severe. Showers will continue today with the most instability
over the valley from about Marysville southward and have included
a threat of thunderstorms here today. Snow levels remain fairly
low at around 3500 feet over Shasta county to about 4000 feet
northern Sierra so have kept snow advisory for coast range,
Shasta mountains and Sierra Cascade range today. Next Pacific
frontal system still poised to move into norcal Friday morning.
Moderate amounts of precipitation are expected with this system
and with relatively low snow levels predicted, combined with
expected gusty winds have kept winter weather advisory over the
coast range and Shasta mountains and bumped up advisory to a
warning over the Sierra Cascade range. Strongest winds appear to
occur around mid day Friday and may top advisory criteria in the
central valley.

Shower activity continues on Saturday under a fairly flat ridge
with enough snowfall over the Sierra to continue the winter
storm warning there. Should see a brief decrease in showers
Saturday afternoon but next system already moving onto the coast
Saturday night. Snowfall rates will begin picking up again late
Saturday night with one to two feet of new snow likely over the
Sierra Sunday. This system will bring another round of heavy
precip and wind through the day Sunday. At this time the tightest
wind gradients appear will occur around mid day so expect
strongest winds then.

&&

.EXTENDED DISCUSSION (Monday THROUGH Thursday)

Transition to amplified upper air pattern forecast for next week
expected to give a break in precipitation to the region beginning
Tuesday. Until then, lingering upper trough will continue showers
across the region on Monday with accumulating snowfall likely
across the foothills and higher terrain.
&&

.AVIATION...

Interior NorCal will be in between stronger storms today with
showers continuing, most numerous over the mountains. Widespread
IFR conditions will continue over the mountains and north end of
the Sacramento Valley while VFR with areas of MVFR will
predominate elsewhere. Deteriorating conditions by 06Z Friday as
the next storm approaches. Southerly winds 10-20 kts today,
increasing to 15-25 kts with gusts 30-40 kts after 06Z Friday.
&&

.STO WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 4 AM PST Friday for West Slope
Northern Sierra Nevada-Western Plumas County/Lassen Park.

Winter Storm Warning from 4 AM Friday to 10 AM PST Saturday for
West Slope Northern Sierra Nevada-Western Plumas County/Lassen
Park.

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

&&

$$



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