Heavy Snow in California, April 22 to 23, 2016

Area Forecast Discussion
National Weather Service Sacramento CA
422 AM PDT FRI APR 22 2016

.Synopsis...
A weather system is moving inland this morning and will spread showers
to much of northern California through tonight. Expect snow above
6000 feet and the possibility of thunderstorms this afternoon into
evening.

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.Discussion...
Radar already showing some moderate to locally heavy rain
developing across the Coastal Range into the western side of the
Sacramento Valley this morning between Lake County up to Shasta
County. Showers will continue to spread east and southward across
our entire CWA today. The high resolution models indicate 2 waves
of precipitation moving inland. The first one occurring now and
the second wave moving into our region around noon. As
precipitation moves eastward, expect snow to impact the Sierra. Highest
snow amounts ranging around 7 to 12 inches will occur above 6000
ft and impact mountain travel today...especially given that this
is a Friday when higher traffic towards Tahoe usually occurs.
Drivers should be prepared for delays and/or chain controls. Don't
forget to check road conditions via CalTrans before traveling over
the Sierra. Winter Weather Advisory remains in effect across the
western Sierra slopes from 8 am to 8 pm today.

Winds are also starting to pick up from Chico northward
to Redding with sustained winds near 20-25 mph and gusts up to 30
mph this morning. Winds should also increase farther south towards
Sacramento region and into the Delta as the day progresses with
similar windspeeds. Wind Advisory remains in effect for Delta &
Sacramento Valley today from 5 am to 5 pm.

In addition to wind, rain, and snow...residents should be prepared
for the possibilty of thunderstorms this afternoon. Best chance
for thunderstorm activity should be in the Sacramento valley and
adjacent foothills this afternoon into evening. Some thunderstorms
could produce hail and rotation (funnel clouds or tornadoes) so
stay sheltered if thunderstorms are in your area.

On Saturday, brief short-wave ridging develops over NorCal which
will dry out most of our area except for some lingering showers
over the Shasta County Mountains. By Sunday, another trough will
move across NorCal which will bring another wave of rain and snow
showers to our region.  JBB

.EXTENDED DISCUSSION (Tuesday THROUGH Friday)

Dry weather is in store for Tuesday as a fast-moving ridge of
high pressure moves over California. The next weather system will
be quick on its heels however, with unsettled weather expected
across NorCal Wednesday into Thursday. There are differences in
the handling of this system between the GFS and ECMWF which would
affect the areal coverage of potential showers. This system will
be slow to track eastward, and could keep wraparound showers
going along north & eastern California going into late next week.

Dang

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.AVIATION...

Weather system has begun to move through Northern California, and
will spread periods of showers across the region today. Expect
mainly VFR/MVFR conditions across Valley TAF sites, with IFR/LIFR
over the mountains. Thunderstorms will be possible across the
Valley, mainly between 18-02z. South winds will increase to 15-22
kt across the Valley today with gusts to 35 kt.

Dang

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.STO Watches/Warnings/Advisories...
Winter Weather Advisory from 8 AM this morning to 8 PM PDT this
evening for West Slope Northern Sierra Nevada-Western Plumas
County/Lassen Park.

Wind Advisory until 5 PM PDT this afternoon for Carquinez Strait
and Delta-Central Sacramento Valley-Northern Sacramento Valley-
Southern Sacramento Valley.

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