Blizzard and Heavy Snow in California, February 26 to 28, 2023

Area Forecast Discussion
National Weather Service Sacramento CA
310 AM PST Sun Feb 26 2023

.SYNOPSIS...
Rain and low-elevation snow into Wednesday with major travel
impacts. Difficult to near impossible travel in the mountains
Monday through Tuesday night.

&&

.Discussion...
Still a few light showers lingering across the region as we're
in-between systems with the big low now moving through SoCal and
the next upstream system approaching northwest California early
this morning. With all the clouds and lingering showers, current
temperatures are milder compared to 24 hours ago with upper 30s to
mid 40s in the valley, and mainly 20s in the mountains.

The next system moves in this morning spreading light to moderate
precipitation across the region. QPF will be generally less than a
third of an inch in the valley with up to 1.5 inches over the
mountains. Snow levels will be around 2-3k ft with around 1-2 ft
of additional snow expected over the mountains. Southerly breezes
will increase later this morning, but will be less than what we
saw Thursday night and Friday morning.

A very brief lull is possible later today and tonight, then a
couple of strong winter storms systems are expected to affect the
area beginning very early Monday morning and continuing through
Tuesday night. Snow levels will be lower, generally 1-2k ft, but
there will be another chance for snow across the northern
Sacramento Valley on Monday into Tuesday. Currently it's looking
like an inch or two for the valley floor north of Red Bluff with 4
or 5 inches possible along the western foothills and far north end
of the valley including Redding.

A strong storm will bring dangerous to near impossible mountain
travel on Monday and Tuesday with 2-7 ft of snow expected along
with gusty winds to 60 mph or higher resulting in zero visibility
in blowing snow. This is a cold system with high ratio, 1:18 at
times. Very high snow rates are possible, 3+ inches an hour Monday
through Tuesday. A Blizzard Warning has been issued for the
northern Sierra and the mountains of western Plumas County and
eastern Butte County for 4 am Monday to 4 am Wednesday.

Southerly winds will increase Monday with gusts up to 45 mph in
the Sacramento Valley. A Wind Advisory has been issued for that
area 4 am to 4 pm Monday.

Unstable conditions will bring the potential for thunderstorms
on Monday and Tuesday. Small hail is the main threat.

The stormy conditions are expected to wrap up on Wednesday as the
main trough shifts east and ridging builds into NorCal from the
eastern Pacific.

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.EXTENDED DISCUSSION (Thursday THROUGH Sunday)...
A ridge of high pressure will build over the region on Thursday,
resulting in dry conditions, lighter north winds for the Valley,
and cold morning lows. NBM projects near to slightly below
freezing temperatures returning to the Valley Thursday morning,
with lows generally in the upper 20s to low 30s. The ridge looks
short lived as a shortwave to the northwest begins to flatten the
ridge on Friday. Ensembles and clusters are in good agreement with
another cold trough impacting the region next weekend. This will
bring another round of Valley rain and moderate to heavy mountain
snow. Snow levels will be 1500-3000 feet. There is a 55-80% chance
of 12 inches or more over the Sierra, so hazardous mountain
travel conditions are possible.

&&

.AVIATION...
Pacific system will gradually spread rain and foothill/mountain
snow after 12Z-15Z today, bringing MVFR/IFR conditions to the
Valley and MVFR/IFR conditions to the mountains. Snow levels
2000-3000 ft today, then 1000-2000 Monday-Tuesday. A stronger
system will bring Valley rain and foothill/mountain snow after 12Z
Monday, with widespread MVFR and areas of IFR/LIFR. Wind gusts
15-30 kts at TAF sites through 03Z Monday. Increasing southerly
winds after 12z-15z Monday.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning until 4 AM PST Wednesday for Burney Basin /
Eastern Shasta County-Motherlode-Mountains Southwestern Shasta
County to Western Colusa County-Northeast Foothills/Sacramento
Valley-Shasta Lake Area / Northern Shasta County-West Slope
Northern Sierra Nevada-Western Plumas County/Lassen Park.

Wind Advisory from 4 AM to 4 PM PST Monday for Carquinez Strait
and Delta-Central Sacramento Valley-Motherlode-Northern
Sacramento Valley-Northern San Joaquin Valley-Southern
Sacramento Valley.

Winter Weather Advisory from 4 AM Monday to 10 AM PST Tuesday
for Central Sacramento Valley-Northern Sacramento Valley.

Blizzard Warning from 4 AM Monday to 4 AM PST Wednesday for
Motherlode-West Slope Northern Sierra Nevada-Western Plumas
County/Lassen Park.

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