Area Forecast Discussion
Issued by NWS Sacramento, CA
FXUS66 KSTO 171712
Area Forecast Discussion
National Weather Service Sacramento CA
912 AM PST Tue Jan 17 2017
Dry today, then a series of winter storms will begin Wednesday
and continue into early next week.
An elongated upper ridge remains draped over California, extending
inland toward the northern Rockies. High clouds have been moving
over the region this morning and during the overnight hours. This
wasn`t enough to deter a strip of fog and stratus from forming,
extending across much of the Central Valley northward to Redding.
This layer of fog and stratus doesn`t appear to be too thick, and
is expected to burn off by midday to early afternoon.
The first in a series of winter storms is currently well off the
Pacific Northwest coast. Warm advection precipitation is expected
to start along the Northern CA Coastal Ranges as early as this
evening, with the main frontal precipitation expected Wednesday
into Wednesday night. This system doesn`t appear to be as wet as
last week`s storms, with rain forecast totals of 0.50 to 1.50
inches across the Valley, and 1 to 3 inches over the mountains.
Snow levels are expected to primarily hover between 4000 and 5000
feet, with over a foot of snow accumulation forecast over higher
terrain. South wind gusts of 35 to 45 mph will be possible across
Showery, off-and-on type weather is expected to continue into
Thursday, in advance of the next wintry weather system on Friday.
The Friday system is trending a bit drier. While precipitation is
still expected across the region, we`re now forecasting a bit less
in the way of rain and snow totals than the first storm. Snow
levels are still expected to be lower than the first storm,
potentially down into the Sierra foothills and impacting
Interstate 5 through Shasta County.
.EXTENDED DISCUSSION (Saturday THROUGH Tuesday)
Weak upper ridging moves through Saturday with models suggesting
lingering showers possible over the mountains. Precipitation then
spreads across the area Saturday night into Sunday as next Pacific
frontal system impacts interior NorCal. Significant QPF expected
as models showing upwards of 2+ inches in portions of the Central
Valley Sunday through Monday with 3+ inches in the foothills and
mountains. Snow possible down into the foothills with this system
and several feet of new snow expected at pass levels impacting
travel. Strong southerly winds forecast Sunday and wind advisories
may be issued for portions of Interior NorCal. Decreasing showers
Tuesday as weak high pressure returns to the forecast area.
Upr rdg movs thru tda as Pac fntl sys apchs. Areas MVFR/IFR with
isold LIFR poss in ST/BR/FG in Cntrl Vly til arnd 21z otrw VFR
conds for Intr NorCal tda with incrsg mid to high clds. Sfc wnds
mnly lgt thru tngt. Lcl MVFR conds in pcpn acrs Nrn/Cstl mtns aft
Winter Storm Watch from Wednesday afternoon through Thursday
morning for West Slope Northern Sierra Nevada-Western Plumas