678
FXUS66 KSTO 261953
AFDSTO
Area Forecast Discussion
National Weather Service Sacramento CA
1153 AM PST Fri Dec 26 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
today.
- Heavy snow is expected through tonight, 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.
- Mountain showers linger Saturday, with drier weather expected
Sunday into early next week. Fog/low clouds possible in the
Valley/foothills once again.
&&
.DISCUSSION...
...Today & Saturday...
A period of clearing skies in the central Valley evident on
satellite imagery this morning will provide another opportunity
for isolated thunderstorm development this afternoon and early
evening as the final few waves of atmospheric river moisture
progress through interior NorCal. The most likely time frame for
thunderstorms in the Valley and lower foothills will be between
noon and 8 pm. Given a still moisture-rich environment with modest
instability and synoptic scale support, gusty winds, small hail,
heavy rain, and isolated tornadoes remain possible with any
stronger thunderstorms that do develop. Flooding impacts remain
possible as well for the Valley and lower foothills through the
evening in periods of heavy rain.
Across the mountains, snow levels are expected to remain steady
around 4000 to 5000 feet through the afternoon and evening. Snow
showers continue to provide brief bursts of moderate to heavy
snowfall in the early afternoon, with heavy snowfall becoming more
widespread as lower elevation convection moves up the terrain
later in the afternoon and through the evening. Snowfall rates of
1 to 2 inches per hour will remain likely through the evening. As
a result, an additional 8 to 12 inches will be possible above
4500 feet with up to 15 inches possible over peaks through
Saturday morning.
In addition to the precipitation impacts, breezy to gusty
southerly winds are expected to continue this afternoon and
evening as the weather system moves onshore. Strongest gusts up to
45 mph are expected across the northern Sacramento Valley. A
brief lull in gusty winds is expected into the overnight hours as
the system progresses eastward, with a period of breezier north
winds gusting up to 20 mph at times to follow on Saturday.
Otherwise, cool and mostly dry weather looks to settle in by
Saturday for the Valley/foothills with light snow showers
remaining possible along the Sierra throughout the day.
Despite the system gradually beginning to wind down today,
periods of gusty winds, heavy rain/mountain snow, and thunderstorm
chances will result in difficult to dangerous travel conditions
persisting through the evening and likely lingering at least into
Saturday morning across the mountains. If you have travel plans
plan ahead, 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.
...Sunday Into Next Week...
As the holiday week weather system finally wraps up across
interior NorCal, ensemble guidance is uniformly indicating an
amplifying ridge building into the region late weekend into early
next week. This brief pattern shift will usher in a period of
drier weather through the middle of next week. Despite this, the
expected stagnating weather pattern will likely plunge Valley and
foothills locations back into a similar cycle of fog and low
clouds seen earlier this month. While the building ridge does look
to amplify early in the week, latest ensemble guidance is
depicting a closed low offshore of SoCal pushing northward as a
Gulf of Alaska trough digs southward mid to late next week. Exact
implications of this remain relatively uncertain, but this trend
will likely result in the return of unsettled weather to the
region by the new year at the very least.
&&
.AVIATION...
MVFR/VFR conditions are forecast to prevail through the afternoon
and evening hours as a final wave of precipitation moves from
northwest to southeast through the region. Could see some isolated
thunderstorms embedded within this line, particularly for the
Sacramento Area terminals. Any storms near a TAF location may
reduce visibilities from heavy rain with brief IFR conditions, and
would be accompanied by gusty/erratic winds. Snow levels are
currently around 4500 feet in the Sierra and 3500-4500 feet in the
Coastal Range/southern Cascades.
&&
.STO WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning until 10 PM PST this evening 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.
Flood Watch until 4 PM PST this 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.
Wind Advisory until 6 PM PST this evening for Carquinez Strait
and Delta-Central Sacramento Valley-Motherlode-Northeast
Foothills/Sacramento Valley-Northern Sacramento Valley-Northern
San Joaquin Valley-Southern Sacramento Valley.
&&
$$
