O'Brien, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

376
FXUS66 KSTO 221106
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
306 AM PST Sun Dec 22 2024

.SYNOPSIS...
Periodic chances for precipitation and breezy to gusty southerly
winds are expected through the weekend and into next week as a
series of weather systems impacts the region.

.DISCUSSION...
Scattered rain showers continue over the motherlode and areas
south of Interstate 80 around midnight this morning as Saturday`s
weather comes to a close. Before the rain moves into the area,
there will be areas of low stratus and fog across the Valley with
areas south of Red Bluff already seeing pockets of low stratus
clouds occurring over the area.

There is still some uncertainty of when the next weather system
begins with some models showing late Sunday morning and others not
until mid-Sunday afternoon. Nonetheless, once precipitation
begins, it will continue in the Valley through tonight before
tapering off early Monday morning with showers lingering over the
Sierra. Rain will be the main impact with this periods as snow
levels will be 8000-9000` until colder air moves in Monday
morning. Forecasted amounts for the Valley north of I-80 will be
0.10-0.50" with 0.25-1.00" expected for the mountains and adjacent
foothills from this morning to Monday AM.

Lingering precipitation over the Sierra will continue late Monday
morning as the next wave moves south and east into our forecast
area. This wave will be colder and wetter system in comparison to
this weekend`s weather with snow levels dropping to 5000 to 6000
feet over the Sierra by Tuesday afternoon. From Monday late
morning to Tuesday night, we can expect around 1 to 1.75 inches in
the Valley with 1.50-3.50", up to 4 inches over the foothills and
mountains. Additionally, there is a 10-20% chance of thunderstorm
development main across the Delta, Sacramento Valley, and
adjacent foothills as our trough swings through Northern CA. Best
chances will be late Tuesday morning through the afternoon (~10AM
to 6PM). With all this considered, there is an Excessive Rain
potential highlighted for the foothills north of I-80 and the
Northern Sacramento Valley for Monday and across all of the
Sierra foothills on Tuesday. With the trough moving through the
area, this should also carry breezy winds with south winds gusts
20-35 MPH expected across the Valley and foothills Monday night
through Tuesday afternoon with gusts up to 45-50 MPH over the
Sierra Crest.

Snow will also accompany this wave with moderate travel impacts
expected Christmas Eve from snow-covered and slick roads and
reduced visibilities at times. Snow forecasted above 6000 feet for
the Sierra is 3 to 8 inches, up to a foot along the crest
generally seeing higher amounts as you move further south along
the Range. Probabilities show a 50-90% chance of 8 inches or more
above 6500 feet and 15-35% around 6000 feet with the highest
chances along and south of HWY 50. By Wednesday, we will be gifted
a brief lull in active weather with a dry Christmas morning and
afternoon and light north winds in the morning. All signs point to
continued minor to moderate precipitation impacts late Wednesday
night/early Thursday AM into the middle of next weekend with
periods of widespread rain and mountain snow.

Please continue to check weather.gov/sto for the latest updates
and check quickmap.gov.ca.us before you go this holiday season!

.EXTENDED DISCUSSION (Thursday THROUGH Sunday)...

We should expect continued precipitation impacts Thursday leading
into the weekend with current probabilities of total
accumulations greater than 2 inches around a 20-40% chance north
of I-80 in the Valley with a 60-90% chance over the mountains and
N. Sacramento Valley. There is still some disagreement regarding
exact totals this far out but minor to moderate travel impacts can
be expected. Similarly, there is disagreement on exact snow
totals but current probabilities show around a 30-60% chance of
totals greater than 6 inches above 6000 feet. Afternoon highs
should remain relatively the same with only 2-5 degrees in
fluctuation each day, remaining in the 50s and low 60s in the
Valley with 30s to low 50s across the mountains and foothills
respectively.

&&

.AVIATION...

MVFR/IFR conditions in showers expected next 24 hours, with snow
levels generally above 7000-8500 feet. Widespread LIFR cigs and
areas of BR/FG possible until around 18Z Sunday. Surface winds
generally below 12 kts, except for gusts 20-30 kts possible along
the Sierra crest after 00Z-03Z Monday.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$