485
FXUS66 KSTO 091018
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
218 AM PST Mon Nov 9 2026

.KEY MESSAGES...

 - Dry weather, above normal temperatures, and periodically breezy
   north to east winds Tuesday through Friday morning

 - Shift toward active weather pattern late week into early the
   next week, with the potential for heavy rain and heavy mountain
   snow, and gusty onshore winds; Low confidence persists in the
   timing and amount of potential precipitation

&&

.DISCUSSION...

Today-Thursday:

An approaching weak shortwave is bringing a band of high-level
clouds across the northern portion of the forecast area, while low
clouds and patchy fog/mist have been developing overnight in the
Delta and portions of the southern Sacramento Valley and northern
San Joaquin Valley with clear skies. This fog and mist are
expected to quickly mix out and disperse by late morning.

High pressure will flatten slightly today as the aforementioned
weak shortwave trough pass to the north. This feature will bring a
slight chance of light showers into far northwestern Shasta
County this afternoon. Otherwise, mostly dry and seasonably warm
temperatures. There is a potential for fog/mist late tonight into
Tuesday morning, but mainly south of I-80, with a 30-70% chance of
visibility dropping below a mile.

Temperatures peak on Tuesday as the the high pressure will build
back, with temperatures about 10 degrees above normal for this
time of year. This will aid in high temperatures for the Delta,
Valley and Foothills peaking into the mid 60s to mid 70s. Dry and
warm temperatures will persist through early Friday, with little
change day to day through Thursday. This pattern will bring some
breezy northerly winds in the Valley Tuesday, though gusts should
generally be limited to 15 to 20 mph, peaking mid- day. East to
northeast winds develop over mountain ridges and through canyons
Tuesday night into early Wednesday, with gusts locally to around
20 to 30 mph.


Friday through Sunday:

Ensembles continue to show the potential for a shift toward an
active weather pattern by the weekend, with chances for heavy
rain, heavy mountain snow and gusty winds. However, cluster
guidance still indicates uncertainty regarding the exact position,
timing and development an approaching trough from the Gulf of
Alaska toward the California coast. The main trough moves inland
Friday into the weekend, with the ridging shifting eastward. This
brings the general onset of precipitation from sometime between
Friday and Saturday. The likely wettest period will be over the
weekend. The spread between forecast low and high end amounts of
rainfall and mountain snow totals remains quite large, with a
range of possibilities. Overall though, confidence in a cool, wet,
unsettled pattern late week into early the next week continues to
increase. Anyone with travel or outdoor plans should be sure to
stay up to date with the latest forecast information.

&&

.AVIATION...

Mainly VFR conditions at TAF sites, with a 40-70% chance
for MVFR/IFR visibility reductions in FG/BR at Valley and Delta
sites returning at times through 17z. Light and variable winds
persist across the forecast period at TAF sites.

&&

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

&&

$$