864
FXUS66 KSTO 101107
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
307 AM PST Tue Nov 10 2026

.KEY MESSAGES...

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

 - Increased confidence in an active weather pattern Friday
   through early the next week

 - Gusty southerly winds on Friday and Saturday, trending
   stronger

 - Increasing potential for widespread rain, moderate to heavy
   rain and snow in the mountains; Low confidence persists in the
   exact timing and amount of potential precipitation

&&

.DISCUSSION...

Today-Thursday:

High pressure rebuilds today and amplifies across the interior
Western Region through Wednesday, while an upper-level trough
over the Gulf of Alaska deepens off the West Coast. After some
morning valley low clouds and patchy fog/mist (mainly south of
I-80), expect mostly sunny, breezy, and warm conditions today.
Temperatures will peak this afternoon, running about 10 degrees
above normal for this time of year, with highs reaching the mid to
upper 70s across the Delta, Valley and Foothills.

Dry and warm conditions will persist through Thursday, with
periods of breezy north to east winds at time. Expect breezy
north winds across the Valley, with gusts limited to 15 to 20 mph,
peaking mid- day. East to northeast winds develop over mountain
ridges and through canyons tonight into early Wednesday, with
gusts locally to around 20 to 25 mph.


Friday through Monday:

Confidence continues to increase in a cool, wet, and unsettled
weather pattern Friday through early next week as a series of
shortwave trough and associated frontal systems along an IVT
plume impacts the area with periods of moderate to heavy rain,
higher mountain snow and strong south winds. There is still
uncertainty regarding specific precipitation amounts and peak wind
gusts; however, we are certain that will be wet, with a 75%
chance of widespread precipitation throughout Northern California.

The first of a series of shortwave is expected to approach the
area late Thursday/Friday. This system will contain anomalously
precipitable water (around 200% above normal), enhanced southerly
winds, and IVT values greater than 250 kg/m/s. The current models
suggest the wettest period Friday into Saturday, with rainfall
forecast rainfall totals range from 1-3" for the mountains,
0.50-1" in the Valley and Delta. There is also the potential for
isolated thunderstorms Friday, with a 10-25% probability in the
afternoon. The second system is expected to move in Saturday night
through Monday, with an additional period of moderate to heavy
rain. 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.

Anyone with weekend mountain travel should be sure to stay up to
date with the latest forecast information. Snow levels start
around 7000-8000`, dropping to 5000-6000` Sunday night, to around
5000` Monday. There is a 50-75% probability of storm total
snowfall greater than 8" by Monday afternoon over the Sierra and
around the Lassen NP area. There is about a 40-60% chance for more
than a foot of snow.

A notable change in the forecast has been an increase in winder
outdoor plansgusts late in the week, particularly on Friday, as
well for the weekend. 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, northeast foothills and across the
Sierra. There is a 60-85% probability of gusts greater than 40
mph for the northern Sacramento Valley centered around Red Bluff
and the northeast foothills. 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 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.


 &&

.AVIATION...

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

&&

.STO WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$