Weather Service Report


886 
FXUS66 KSTO 070516
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
916 PM PST Tue Dec 6 2016

.SYNOPSIS...
Cold overnight temperatures again tonight. A return to wetter 
weather is expected Wednesday through Saturday, and again next
week.

&&

.DISCUSSION...
Temperatures are trending much cooler this evening thanks to the
clear skies and slightly cooler air and drier air over the region.
Widespread morning lows around the freezing mark or below with 
some of the colder spots dipping into the upper 20s looks likely. 
Mountain valley lows will get very cold dipping into the single 
digits and teens. Some high clouds will drift over the region 
Wednesday morning and should help to mitigate the low 
temperatures a little. Fog looks likely to develop again overnight
with the most dense fog likely around sunrise and just after for
an hour or two.

A moderate system moves into the region Wednesday night into 
Thursday. A few showers may occur in the afternoon over the
mountains but for the most part it looks like the rain and snow
will hold off until Wednesday night. Snow levels should be low to
start Wednesday night but rise on Thursday to near or just above 
pass levels by mid to late morning. Some impacts may occur over
Shasta County as a result with some snow possibly lowering to
around 1500 ft and the Burney Basin getting at least several 
inches of snow. The western slopes near pass levels should get
around half a foot before snow levels rise above 

Steady precipitation especially for the Sierra Nevada will 
stream over the region into Saturday.

&&
.EXTENDED DISCUSSION (Saturday THROUGH Tuesday)


Active large scale pattern will continue through the extended
forecast. Forecast models disagree on Saturday regarding shower 
activity as upper energy pushes eastward. Precipitation amounts 
and coverage and amounts differ this far out, with the GFS being 
the driest solution. Have blended the solutions given model 
uncertainty. Snow levels will be generally above 5000 feet on 
Saturday over the northern Sierra, which could result in some 
hazardous mountain travel.

Guidance suggests there could be a brief lull in shower 
activity Saturday night into early Sunday before the next system 
moves in early next week. There are differences in timing and 
evolution of this system as the GFS is the fastest solution. 
Regardless, widespread precipitation can be expected across the
forecast area. Snow levels around 3500 feet across northern 
mountains and 4500 to 5500 feet in the Sierra on Monday, then 
increasing into Tuesday with the warm air advection. Additional 
waves of precipitation will continue at least through the middle 
of next week so stay tuned for updates. 

&&

.AVIATION...


Areas of Valley MVFR and local IFR to LIFR generally south of MYV
due to BR/FG through 18z Wednesday. Light northerly flow under 10
kts thru the period. Precipitation should approach the Coastal 
Range mainly after 20z Wednesday as a storm system approaches.


&&

.STO WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 4 PM Wednesday to 10 AM PST 
Thursday for West Slope Northern Sierra Nevada-Western Plumas 
County/Lassen Park.

Freeze Warning until 9 AM PST Wednesday for Carquinez Strait and 
Delta-Central Sacramento Valley-Clear Lake/Southern Lake County-
Motherlode-Northeast Foothills/Sacramento Valley-Northern 
Sacramento Valley-Northern San Joaquin Valley-Southern 
Sacramento Valley.

Winter Weather Advisory from 4 PM Wednesday to 10 AM PST 
Thursday for Shasta Lake Area / Northern Shasta County.

&&

$$

Return to Home page


Western Regional Climate Center, wrcc@dri.edu