075
FXUS66 KSTO 032033
AFDSTO
Area Forecast Discussion
National Weather Service Sacramento CA
1233 PM PST Sat Jan 3 2026
For additional details on weather and expected impacts over the
next 7 days, please visit weather.gov/sto/briefing.
.KEY MESSAGES...
- Major mountain travel impacts above 5000 feet this weekend
through Monday with white out conditions at times.
- Heavy rain, scattered thunderstorms, and gusty winds this
weekend. Urban and small stream flooding may result from heavy
rains.
- Drier weather on Tuesday, with another round of showers and
mountain snow mid-week.
&&
.DISCUSSION...
...Today through Monday...
Current satellite and radar has an area of showers and storms
around the Sacramento Valley, with scattered to broken clouds
elsewhere. Some of these storms have the potential to be on the
stronger side, with gusty winds and small hail. Environmental
conditions across the area has sufficient low level shear, sfc
vorticity, MUCAPE around 250-500 J/kg, and sufficient moisture
transport. This has been picked up in the CAMS over the past
several runs. Storm mode starts off multi cellular and goes linear
quickly. We will continue to monitor the thunderstorms as they
develop and push through the Valley. Their remains the chance for
isolated strong to severe storms this afternoon and early
evening.
Otherwise, the upper level trough off the coast of CA will
continue to shift onshore, with a broad area of precipitation just
off the coast moving into Eurekas forecast region. This will push
through our area this afternoon and evening, with another band of
precipitation overnight. Between the waves of precipitation we
will see pop up showers and isolated thunderstorms. Rainfall will
be moderate to heavy at times especially around thunderstorm
activity where rates up to an inch per hour are possible (40
percent chance). Areas near Shasta will start to see a convergence
zone develop this afternoon and evening bringing moderate to
heavy rainfall and potential for training thunderstorms. HIRES
guidance continues to pick this up. We will monitor this closely
as this has the possibility of producing flooding conditions.
Heaviest rainfall will move in overnight and continue through the
mid morning, with another wave Sunday afternoon and evening.
Coverage will be widespread these times. Lowest rainfall totals
will be located in the northern San Joaquin Valley and portions of
the Delta.
Snow levels will continue to drop toward 5000-6000 feet this
afternoon through Sunday morning, reaching 4500 feet Monday
morning. Heavy snow is expected within the Sierra mountains and
highest peaks for the southern Cascades and Coastal Range. Total
snow accumulations of 6 to 10 inches above 4500 feet. 1 to 3 feet
above 5000 feet, and 3 to 5 feet above 6000 feet. Locally higher
amounts at highest peaks. Winds gusting as high as 55 mph will
help create near white out conditions within the mountains. Travel
could be very difficult to impossible through passes this weekend
and into Monday. A Winter Storm Warning is effect for the Sierra
through Monday for the heavy snow and strong winds. If you plan to
travel make sure you have alternate routes, backup plans, and
carry a safety kit with you at all times.
Winds will continue to be breezy out of the south for the
Sacramento Valley, with the strongest north of Chico. Gusts up to
45mph are possible for the northern Sacramento Valley, with up to
30mph elsewhere. Otherwise, we will have lingering impacts on
Monday morning and afternoon as the main upper level system moves
out of the region.
...Tuesday Onward...
Dry conditions are expected Tuesday morning and afternoon, before
another system starts to shift near the region. Guidance struggles
with the development, track, and strength of the system, but
precipitation is expected in the mountains. At this time snowfall
looks to be light to moderate as the system moves through
Wednesday and into Wednesday night. Chances for a few showers
within the Valley and into the foothills. Post Thursday, long
range guidance hints at a quieter pattern setting up for the
area.
&&
.AVIATION...
Rain will overspread the area as a wave of precipitation moves
onshore and through the Valley. Chances for thunderstorms for
each TAF site this afternoon, with diminishing chances by this
evening and overnight. Lull in precipitation post 3z for sites in
Sacramento points southward, while RDD and RBL will continue to
see chances. Another wave of precipitation moves through tonight
and into tomorrow morning, with coverage being widespread.
Visibilities will fluctuate between 2SM and 6SM when around
thunderstorms and rain. Winds will be breezy out of the south for
each site, with RBL and RDD seeing gusts 35 to 40kts. Other
locations will see gusts between 20 and 30kts. Winds slowly
subside overnight and into tomorrow morning.
&&
.STO WATCHES/WARNINGS/ADVISORIES...
Flood Watch through Monday afternoon for Central Sacramento
Valley-Motherlode-Mountains Southwestern Shasta County to
Western Colusa County-Northeast Foothills/Sacramento Valley-
Northern Sacramento Valley-Shasta Lake Area / Northern Shasta
County-Southern Sacramento Valley.
Wind Advisory until 4 AM PST Sunday for Central Sacramento
Valley-Northeast Foothills/Sacramento Valley-Northern Sacramento
Valley.
Winter Storm Warning until 4 PM PST Monday for West Slope
Northern Sierra Nevada-Western Plumas County/Lassen Park.
&&
$$
