808
FXUS66 KSTO 092116
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
216 PM PDT Sun Mar 9 2025

.SYNOPSIS...
Dry and seasonable weather with some occasional breezy winds into
early next week. An active weather pattern is expected from
Wednesday through the end of the week. Periods of moderate to
heavy rain and mountain snow along with gusty winds will bring
significant travel impacts to interior NorCal, especially mid-
week.

&&

.DISCUSSION...
Dry and seasonable weather continues today as ridging remains the
dominant feature over interior NorCal. Above average temperatures
are expected today and Monday with high temperatures in the mid
60s to low 70s in the Valley, and 50s to 60s in the foothills and
mountains.

Overnight Tuesday and into Wednesday, a new low pressure system
arrives to the area, bringing widespread precipitation and gusty
winds. Most of the impacts from this system won`t be fully felt
until Wednesday. While Tuesday afternoon will see some breezy to
gusty winds (primarily in the foothills, mountains, and northern
Sacramento Vally), the strongest and most widespread winds will
occur on Wednesday. Notably, we will need to continue to monitor
winds over the northeastern foothills for Tuesday evening as winds
are approaching 40-50 MPH gusts possible. The National Blend of
Models has a 15 to 40% chance of gusts that are 40 mph or higher
in the southern Sacramento and northern San Joaquin Valleys, 50 to
85% in the central and northern Sacramento Valley and the
foothills, and a 40 to 75% chance of 50 mph or higher gusts in the
mountains.

Widespread precipitation also arrives Wednesday morning, and
continues into Thursday. Snow levels generally look to start
around 3500 to 5500 feet across the mountains, lowest over the
Coast Range and Shasta County. There will be decreasing snow
levels from west to east and by Wednesday night be as low as 2500
feet for the Coast Range/Shasta County and 3000 to 4500 feet over
the Sierra. Snow levels become 2000 to 3000 feet by Thursday
morning across much of the area before briefly nudging up during
the day.

Over these 48 hours, there is a 50-75% chance of 1 foot from 4000
to 6500 feet, 40 to 75% chance of 3 feet or more above 5000 feet,
35 to 75% chance for 6 inches or more between 3000 and 4000 feet.
While much lower amounts down to around 2500 feet can`t be ruled
out, chances are dwindling for measurable snow below 3000 feet.

As a result, Winter Storm Watches have been issued for the Sierra,
Southern Cascades/W. Plumas Counties for above 4000 feet, and
Shasta County Mountains/Coast Range above 3000 feet from Tuesday
Evening to Thursday Evening for periods of heavy snow and gusty
winds causing major travel impacts. Difficult road conditions are
expected with chain controls and possible road closures. Please
make sure to check the latest forecast and road conditions before
making any mountainous travel this week as the mountains will see
periods of active weather throughout the entirety of the week

Lower elevations will see moderate to heavy rainfall on Wednesday
and into Thursday as well. The NBM has a 25 to 50% chance of 1
inch or more of rain across the Valley from roughly the Southern
Sacramento Valley to just south of the Northern Sac. Valley and
40-70% chance across the foothills. NBM also shows a 50-80% (Up
to 85-90% near the Feather River Valley area) of 2 inches or more
across the mountains to Northern Sacramento Valley. Thunderstorm
chances have decreased for Wednesday with only 10-15% chance over
the Delta and Central to Northern Sac. Valley with their adjacent
foothills before 15-25% chances on Thursday across the Valley and
adjacent foothills mainly.

&&

.EXTENDED DISCUSSION (Thursday THROUGH Sunday)...

As previously discussed, widespread precipitation and gusty winds
will continue into Thursday, though the bulk of the impacts will
occur Wednesday. There is an additional 10 to 20% chance for
isolated thunderstorms on Thursday in the Valley and foothills.
Chances on Thursday seem a little bit stronger, though any
eventual activity will be dependent on how much clearing occurs by
Thursday afternoon. Right now, there are fairly equal chances
across the Valley and foothills for any thunderstorm activity,
though the EFI highlights more of the Valley for instability on
Thursday.

Heading into the weekend, a second wave of moisture, aided by a
shortwave trough, will bring further chances for precipitation.
While ensembles and cluster analysis are still somewhat uncertain
on the exact intensity of this system, currently it appears that
rain and snow from this wave of moisture could last long enough to
keep us wet through Sunday (when a new, bigger trough progresses
into interior NorCal). Current probs show a 50-85% chance of an
additional foot of snow across the Sierra above 5000 feet
Thursday and Friday a with 30-60% over the Shasta County
Mtns/Coast Range.
&&

.AVIATION...

VFR conditions expected over the next 24 hours. Southerly winds at
or near 12 kts with gusts up to 20 kts in the Sacramento Valley
today until 02Z. Over the Sierra, southwesterly gusts up to 30 kts
through 02Z Monday. Light winds expected elsewhere.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
Winter Storm Watch from Tuesday evening through Thursday 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.

&&

$$