584
FXUS66 KSTO 262115
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
215 PM PDT Sat Apr 26 2025


.Discussion...

.Synopsis...
An unusually cold low pressure system is moving through the area
today with cool temperatures, cloudy skies and periods of rain
and mountain snow. There is also the potential for some isolated
thunderstorms through this evening. The main impacts from this
system will be snowfall above 5500 feet in the Sierra and
southern Cascades, especially later tonight into early Sunday,
when heaviest snow rates are expected. Showers linger into Sunday,
mainly over higher terrain, with some additional mountain snow
accumulation through the morning. The system exits to the east
late Sunday with warmer and drier weather early next week. A weak
system moves across the area Wednesday with some showers over the
Sierra, potentially a few isolated mountain thunderstorms.
Another weak system is expected Friday into next weekend bringing
mainly mountain showers.

&&

.Key Messages...

* Saturday and Sunday:

-Cool with breezy to gusty onshore winds

-Widespread showers continuing into early Sunday. Chance of
     thunderstorms (10-20%) south of I-80 and east of I-5 through
     this evening.

-Snow expected above 5500 feet into Sunday
-70-90% probability of 4 inches or more of additional snowfall
         above 6000 feet along Sierra/southern Cascades, 50-70% of 6
         inches or more.

* Monday-Wednesday:

-Warming trend begins along with drier weather
    -Above normal temperatures with Minor HeatRisk
-Slight chance of showers mountains Wednesday, with isolated
     thunderstorms in the Sierra south of I-80

* Friday and next Saturday

    -Cooling trend returns with chances of showers in the
     mountains, foothills, and northern Sacramento Valley.
    -Isolated mountain thunderstorms possible.
    -Snow levels generally above pass levels, with light high
     elevation snowfall currently expected, though exact details
     remain uncertain at this point.

.Changes from previous forecast...

* No significant changes

&&

.AVIATION...

Mostly VFR conditions across interior NorCal next 24 hours, with
some periods of MVFR/IFR in rain showers through 18Z-21Z Sunday
and brief, isolated thunderstorms through 03Z Sunday. South to west
winds (northwest in N. San Joaquin Valley) generally at or below
12 kts for TAF sites. For the mountains, southwest winds of 10 to
20 kts with gusts 20 to 25 kts.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 11 AM PDT Sunday for West Slope
Northern Sierra Nevada-Western Plumas County/Lassen Park.

&&

$$