Viola, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

068
FXUS66 KSTO 252004
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
1204 PM PST Thu Dec 25 2025

For additional details on weather and expected impacts over the
next 7 days, please visit weather.gov/sto/briefing.


.KEY MESSAGES...

 - Major holiday travel impacts from periods of heavy rain,
   thunderstorms, heavy mountain snow, and gusty winds through
   Friday.

 - Heavy snow is expected through Friday, with snowfall rates of
   1-2" per hour at times.

 - Periods of heavy rainfall are anticipated across the Valley and
   lower foothills with additional flood impacts possible through
   Friday.

&&

.DISCUSSION...

...Today and Friday...

Satellite shows breakage in the clouds and activity across
portions of the Valley, with some areas seeing partly sunny
conditions. Radar tells a different story, with scattered
thunderstorms developing along the Coastal range through the Delta
shifting northeast. We will continue to see redeveloping lines of
precipitation, with embedded thunderstorms through the remainder
of today across the Valley, while areas in the mountains continue
to see heavy snow. Isolated strong to severe thunderstorms this
morning and afternoon, with main hazards being gusty winds, heavy
rain, lightning, small hail, and isolated tornadoes.

HIRES guidance continues to show waves of precipitation moving
through the region today and into Friday, with breaks in between
each wave of filtered sunshine and isolated showers for the
Valley. When the waves of precipitation move through the area, we
can expect moderate to heavy rain, lightning, reduced visibility,
and possible flooding impacts especially in urban and low lying
areas. Rain rates may reach an inch per hour in some of the
stronger thunderstorms or near the Shasta County Convergence zone
that has a potential to develop this afternoon. Confidence is low
on the exact timing, placement, and intensity of it.

Within the mountains heavy snow will continue, with snow levels
around 4500 feet. Some observations near the Sierra have seen a
rain snow mix around 4000 feet this morning due to convection
ongoing nearby. Snowfall rates of 1 to 2 inches an hour have been
observed in the higher elevations last night and this morning.
This will continue through today and tomorrow for the mountains
producing high snow totals. As of right now, total forecasted
accumulations remain on track for the Sierra, Coastal Range, and
southern Cascades. Snow levels will drop for the Coastal and
southern Cascade areas through today toward 3500 feet. As of
right now they are sitting near 4500 feet.

Winds have come down from this morning and overnight, with gusts
around 40-45mph within the Valley and adjacent foothills. Winds
remain strong up in the mountains through today and into
tomorrow. However, areas in the Valley will see breezy southerly
wind gusts of 35-45mph through today and into tomorrow. Thus, we
downgraded the High Wind Warning to a Wind Advisory for the Valley
and adjacent foothills through 10am Friday.

A combination of dangerous mountain travel conditions from heavy,
wet snow and gusty winds and periods of difficult travel at lower
elevations from heavy rain, gusty winds, and thunderstorm chances
are likely through Friday. If you have travel plans, make
alternate routes, have backup plans, and carry safety kits with
you in case of an emergency. If you see flooded areas, turn around
don`t drown.

...Saturday through early next week...

Lingering minor impacts in the mountains from snow showers and
breezy conditions on Saturday, while areas dry out in the Valley.
Conditions dry out everywhere end of the weekend and into early
next week with temperatures in the 40s and 50s. Chances for low
stratus and fog to develop at lower elevations early next week
reducing visibility. As we approach the early part of the new
year, long range guidance has started to pick up on a more active
pattern setting up once again across CA and the southwestern
United States.

&&


.AVIATION...

MVFR/VFR conditions through this afternoon. Current satellite has
breakage in the clouds across the Valley, with showers and storms
developing along the Coastal Range and east of the Sacramento
Metro. We will see waves of moderate to heavy precipitation with
scattered thunderstorms during the afternoon and evening hours
continuing through the overnight. Best chances for thunderstorms
will be this afternoon and evening across the Valley. Isolated
stronger storms can`t be ruled out. Storms near a TAF location may
reduce visibilities from heavy rain, have erratic winds, and
produce lightning. IFR/MVFR conditions in thunderstorms overnight
through the end of the TAF period. Snow levels are currently
around 4500 feet om the Sierra and 3500-4500 feet in the Coastal
Range/southern Cascades.


&&

.STO WATCHES/WARNINGS/ADVISORIES...
Flood Watch through Friday afternoon for Carquinez Strait and
Delta-Central Sacramento Valley-Motherlode-Mountains
Southwestern Shasta County to Western Colusa County-Northeast
Foothills/Sacramento Valley-Northern Sacramento Valley-Northern
San Joaquin Valley-Shasta Lake Area / Northern Shasta County-
Southern Sacramento Valley.

Winter Storm Warning until 10 PM PST Friday for Burney Basin /
Eastern Shasta County-Mountains Southwestern Shasta County to
Western Colusa County-Shasta Lake Area / Northern Shasta County-
West Slope Northern Sierra Nevada-Western Plumas County/Lassen
Park.

Wind Advisory until 10 AM PST Friday for Carquinez Strait and
Delta-Central Sacramento Valley-Motherlode-Northeast
Foothills/Sacramento Valley-Northern Sacramento Valley-Northern
San Joaquin Valley-Southern Sacramento Valley.

&&

$$