353
FXUS66 KSTO 121916
AFDSTO
Area Forecast Discussion
National Weather Service Sacramento CA
1216 PM PDT Sun Apr 12 2026
For additional details on weather and expected impacts over the
next 7 days, please visit weather.gov/sto/briefing.
.KEY MESSAGES...
- Active weather continues today with showers, heavy mountain
snow, gusty winds, and thunderstorms. Lingering mountain
showers into Monday.
- Winter Storm Warning in effect for the Sierra and Southern
Cascades through this evening.
- Gradual warming and drying trend this week, except for light
mountain showers Wednesday-Thursday. Breezy north to east winds
return late week.
&&
.DISCUSSION...
...Today - Monday...
Active weather continues across the area today as an upper low
moves overhead, bringing showers, heavy mountain snow, breezy
winds, and thunderstorms to the area (25-40% probability). Latest
radar imagery shows scattered showers and isolated thunderstorm
activity through the Valley and foothills, with scattered snow in
the mountains above 4000-5000 feet. Instability and shear profiles
suggest the potential for isolated strong to severe thunderstorms
this afternoon and evening. Latest Hi-Res guidance shows a line
of showers and thunderstorms moving across the area into early
this afternoon, with the potential for additional thunderstorms
the rest of the afternoon and evening hours. As the low pressure
moves through, colder air shifts down, which could bring a
slightly increased chance for cold air funnels to the area during
the day on Sunday. Additional storm threats include 1+ inch hail,
accumulating hail, strong winds, and localized flooding from heavy
rain. Stay alert and stay prepared by having a way to receive
watches, warnings, and statement this afternoon and evening.
Snow levels today will be around 4000-5000 feet, but could lower
as low as 3500 feet in heavier convective showers. The heaviest
snow is expected through this evening, with snowfall rates up to
1+ inch per hour. A Winter Storm Warning remains in effect for
the northern Sierra and southern Cascades through 11 PM tonight.
Additional snow accumulations of 6 to 12 inches are expected
above 4500 feet, with up to 18 inches at the highest peaks. Minor
snowfall accumulations up to 1 to 3 inches down to 4000 feet.
Wind gusts as high as 40 mph. Mountain travel could be very
difficult to impossible.
Breezy southerly winds are expected through this afternoon, with
gusts up to 20-30 mph within portions of the Valley, northeast
foothills, and mountains.
Lingering mountain showers are expected on Monday with minor
impacts. In addition, the latest NBM suggests the potential for
thunderstorm development over the Sierra south of Highway 88
(10-20% chance). Elsewhere, dry conditions are expected.
... Early to Late Week...
A return to drier and warmer conditions is expected early to mid
next week with drier northwest flow. Signal is there for brief
showers and mountain snow showers Wednesday and Thursday as the
next trough drops down over the Great Basin area. NBM suggests a
20-50% probability of precipitation greater than 0.25 inches over
the mountains; highest chances in Shasta County.
In addition, breezy northerly to easterly winds develop Thursday
and Friday. The strongest winds are expected on Thursday,
especially along and west of the I-5 corridor within the
Sacramento Valley and mountains.
&&
.AVIATION...
Areas of MVFR and IFR conditions in showers or thunderstorms
through late tonight. Thunderstorm chances increase this
afternoon and evening and continue into the overnight hours. Winds
may be erratic with direction and speed in and around
thunderstorm activity. Surface winds will be breezy out of the
south, with gusts up to 20-25 kts at times in the Valley through
this afternoon and up to 30-35 kts over the mountains through
tonight. Otherwise, surface winds less than 12 kts are expected on
Monday. Lingering mountain snow showers are expected through
Monday, with the potential for isolated thunderstorms over the
Sierra in Tuolumne County tomorrow afternoon.
&&
.STO WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning until 11 PM PDT this evening for West Slope
Northern Sierra Nevada-Western Plumas County/Lassen Park.
&&
$$
