958
FXUS66 KSTO 102218
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
218 PM PST Tue Nov 10 2026

.KEY MESSAGES...

 - Dry weather, above normal temperatures, and periodically breezy
   north to east winds through Thursday

 - Increasing potential for widespread rain, moderate to heavy
   rain and snow in the mountains, and gusty southerly winds

 - Winter Storm Watch in effect from Friday morning through Monday
   afternoon for the Sierra and Lassen National Park above 6000`

 - Gusty southerly winds late week, peaking on Friday, with
   additional wind over the weekend

 - Wind Advisory is in effect from 4 am to 7 pm PST Friday for
   the northern Sacramento Valley and portions of the central
   Sacramento Valley

 &&

.DISCUSSION...

Today-Thursday:

Dry and warm conditions will persist through Thursday, with
some north to east winds at times. Temperatures will be seasonably
mild, with highs 5 to 10 degrees above normal.

Confidence is now high in a shift to a cool, wet, and unsettled
weather pattern Friday through early next week as a series of
shortwave trough and associated frontal systems along a
subtropical moisture plume impacts the area with periods of
moderate to heavy rain, mountain snow and strong southerly winds.

Friday through Monday:

The first of a series of shortwaves is expected to approach the
area late Thursday/Friday, spreading widespread precipitation by
mid-day Friday. This first system has trended stronger and will
tap into anomalously precipitable water (around 200% above
normal), providing ample moisture along with strong lift for
periods of moderate to heavy rain. The current models suggest the
wettest period is now Friday afternoon into Saturday, with
forecast rainfall totals for that period ranging from 1-3" for
the mountains, 0.33-.66" in the Valley and Delta. There is also
the potential for isolated thunderstorms Friday afternoon and
evening, with a 10-25% probability in the afternoon, highest in
the mountains and foothills north of I-80. With
a relatively slow start to the water year, the ground is not
saturated and rivers/streams are relatively low, which help to
mitigate flood concerns, but locally heavy rain could cause local
flooding, mainly ponding on roads with clogged drains.

Anyone with weekend mountain travel should be sure to stay up to
date with the latest forecast information as confidence in winter
weather impacts have increased, with a Winter Storm Watch now in
effect Friday morning through Monday afternoon. The potential for
moderate to heavy snow increases Friday afternoon, peaking in the
evening and overnight. Snow levels start around 7000-8000`,
dropping to 5500-6500` Saturday morning. There is a 50-90% chance
of 8" of snow for the Sierra and around the Lassen Volcanic
National Park area above 6500 feet through 4 am Saturday. There is
currently a lull period of lighter snow during the day Saturday,
but model fluctuations make confidence in this timing currently
low. A second system is expected to move in Saturday night through
Monday, with an additional precipitation, including mountain
snow, with snow levels dropping to around 5000 feet. Snow totals
of around a foot are expected through both systems, with up to 2
feet over higher peaks.

Gusty winds are expected on Friday, and again on Sunday, though
not as strong. A frontal boundary will bring increasing southerly
winds late Thursday night, and peak up on Friday. It will be more
unstable and strong winds aloft Friday afternoon/evening most
likely mix down to the surface, especially near or along the
surface front. The strongest winds are expected to develop over
the northern Sacramento Valley and across the Sierra. There is now a
80-90% probability of gusts greater than 40 mph for the northern
Sacramento Valley centered around Red Bluff. Gusts to 30 to 40 mph
are forecast for much of the rest of the Valley and Delta, and up
to 60 mph in the Sierra. Gusty but slightly weaker winds are
expected for the weekend as well. Wind gusts like these could make
driving difficult, as well as bring down tree branches, bring
local power outages and blow down unsecured objects. ECMWF
Extreme Forecast Index (EFI) highlight Thursday night through
Friday in the 75th-85th percentile above normal wind gusts,
specifically for northern Sacramento Valley, northeast foothills
and northern Sierra, while in the 50th-70th percentile for areas
south of I-80. This will have to monitored, to see if the area of
concern expands southward.

&&

.AVIATION...

Mainly VFR conditions at TAF sites, with local MVFR/IFR
visibility reductions in FG/BR for the northern San Joaquin
Valley possible from 10Z through 18z. Light and variable winds
persist across the forecast period at TAF sites.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
Wind Advisory from 4 AM to 7 PM PST Friday for Butte County
Below 1000 ft-Central Glenn Co & Interstate 5-Eastern Glenn
County-N. Sac Valley in Tehama County-Shasta Metro.

Winter Storm Watch from Friday morning through Monday afternoon
for Lassen Volcanic NP-Sierra (Cal-Tuo) Above 5000 ft-Sierra (El
Dorado-Amador) Above 5000 ft-Sierra (Sierra-Placer) Above 5000
ft.

&&

$$