042
FXUS66 KSTO 192012
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
1212 PM PST Mon Jan 19 2026

.KEY MESSAGES...

 - Dry weather prevails with Valley fog/low clouds

 - Warm and dry weather at higher elevations with periodically
   breezy offshore flow

 - Precipitation chances have trended down for the weekend but
   minor cooling is still anticipated

&&

.DISCUSSION...

...Today Through Thursday...
Latest GOES-West visible satellite imagery depicts a large area
of fog stretching from about Corning southward on this Monday
afternoon. The Dense Fog Advisory has been extended in time
through 2 PM this afternoon as dense fog and visibilities of 1/4
mile or less are still being observed. The region remains under
upper level ridging over the next several days, with dry and mild
weather prevailing for much of interior northern California. This
inversion pattern is bringing daily chances for fog and low clouds
in the Valley and lower foothills through the week, especially
from Chico southward. High resolution guidance shows a 50 to 70
percent chance of visibilities less than 1/2 mile once again
tonight into Tuesday morning. The fog and low clouds will delay
some of the daytime heating in those lower elevations. Be sure to
slow down, and use low-beam headlights if fog is encountered while
driving. Elsewhere, above normal temperatures are forecast, along
with offshore flow.

...Friday - This Weekend...
Toward the second half of the week, the upper level pattern will
feature a flattening ridge, with an upper low developing and
moving into the southern California area which will bring slightly
cooler temperatures for us up north by the end of the week and
into the weekend. Precipitation chances have trended down for the
weekend, with now only a 10 percent chance or less of 0.01" of
rain showers over the northern mountains and southern Cascades.
Confidence is higher in a minor cooling trend in temperatures,
with forecast highs in the 50s to around 60 for the Valley.
Ensemble guidance then indicats the upper level ridge building
back in behind the trough, allowing for increased offshore flow.
Another round of periodically breezy north to east flow can be
expected late Friday and over the weekend as a result of this.

&&

.AVIATION...
Lingering IFR/LIFR conditions in central/southern Sacramento
Valley, Delta, and northern San Joaquin Valley through 23z Monday.
FG/BR expected to re-develop around 03z-06z Tuesday with similar
aerial extent as today. There is some uncertain potential for
FG/BR to reach further north, into Red Bluff, however FG/BR will
be patchier that far north with only MVFR conditions expected.
Surface winds below 12 kts in the lower elevations, with local
E-NE wind gusts of 15-25 kts in the Sierra and Southern Cascades
until 18z Tuesday.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
Dense Fog Advisory until 2 PM PST this afternoon for Carquinez
Strait and Delta-Central Sacramento Valley-Northern San Joaquin
Valley-Southern Sacramento Valley.

&&

$$