Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 221212
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
412 AM PST Sun Jan 22 2017

.Synopsis...
Strong Pacific storm impacting NorCal through tonight with gusty
southerly winds, rain, thunderstorms and heavy mountain snow.
Showers linger Monday then drier weather expected Tuesday through
remainder of next week.

&&

.Discussion...
Strong storm moving through NorCal at this time. Winds have been
increasing across the Central Valley the past hour or two as the
front nears the coast. The KFAT to KRDD gradient is approaching 12
mbs and the KDAX VWP is now indicating 55 kt winds at 1000 feet.
Gusts of 40-50 kts have been reported during the past hour
through the valley. The period of strongest winds will continue
until around sunrise, or until the front passes. Less wind
expected by this afternoon.

Showers and thunderstorms expected today under the post-frontal
unstable airmass. Lightning detecting picking up numerous strikes
offshore. High-res models indicating a fair amount of CAPE through
the valley today, and with strong shear there will be potential
for some stronger storms with hail and non-zero tornado chances.
At this time, the area from Red Bluff to Chico appears to have the
best potential as it will likely see some extended clearing this
morning behind the front. We`ll continue to monitor developments.

Heavy snow will continue in the mountains today with snow levels
2500-3500 feet. Showers continue Monday, then decrease by early
Tuesday as drier northerly flow and subsidence increase over
NorCal.

&&

.EXTENDED DISCUSSION (Thursday THROUGH Sunday)
Models consistant for next Thursday in placing an upper level
ridge over the eastern Pacific while dropping a week trough
southward into the Great Basin. Can not rule out a slight threat
of light showers over the northern mountains and southern Cascades
on Thursday but any precipiation amount will be quite light and
remain over the mountains. By Friday...upper ridge recenters over
the west coast bringing dry conditions entire CWA with daytime
highs several degrees above normal. Upper ridging remains over the
west through the rest of the weekend for continued dry conditions
and above normal temperatures. Light northerly winds through the
period will likely keep valley fog limited mainly to south of
Sacramento. Otherwise fair skies overnight will allow overnight
lows to drop to a little below average.

&&

.AVIATION...
Widespread IFR local LIFR conditions through the morning hours as
strong Pacific frontal system passes through the northstate.
South winds sustained up to 30 knots with gusts to up 50 knots
decreasing after about 15z then south winds 10 to 20 knots after
about 18z. Isolated thunderstorms 18z to 06z valley and foothills.
Mainly IFR conditions through 12z Monday.

&&

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

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

Wind Advisory until 10 AM PST this morning for Carquinez Strait
and Delta-Central Sacramento Valley-Clear Lake/Southern Lake
County-Motherlode-Mountains Southwestern Shasta County to
Northern Lake County-Northeast Foothills/Sacramento Valley-
Northern Sacramento Valley-Northern San Joaquin Valley-Shasta
Lake Area / Northern Shasta County-Southern Sacramento Valley.

High Wind Warning until 6 AM PST early this morning for
Carquinez Strait and Delta-Central Sacramento Valley-Northern
Sacramento Valley-Northern San Joaquin Valley-Southern
Sacramento Valley.

&&

$$



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