Sunnyslope, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

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FXUS66 KSTO 121047
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
247 AM PST Thu Dec 12 2024

.SYNOPSIS...
An active weather pattern is expected to persist through early
next week bringing moderate travel impacts from rounds of
mountain snow, rain, and breezy winds.

.DISCUSSION...
Our dry spell has come to an end with rain ongoing over the
western half of the Central Valley with snow expected over the
mountains through much of tomorrow. Early this morning will see
the heaviest period of rain, mainly over the western portions of
the Valley with periods of moderate to heavy snow over the Sierra
throughout the remainder of the morning. This is the first of
several waves of active precipitation from now into early next
week, with light precipitation bridging the periods of heavier
rain/snow rates. Now through early Friday morning will be the
first bulk of precipitation with 0.50-1.00" expected for the
Valley and 1.00-2.25" over the mountains and Northern Sacramento
Valley.

Snow is ongoing across the Coastal Range with chain controls
being observed across various highways crossing higher terrain. A
Winter Advisories are in effect for the mountains of Shasta County
down to around to 3500 feet for snow accumulations of 4 to 9
inches and the West Slope Northern Sierra Nevada/Western Plumas
County/Lassen Park counties for snow accumulations of 6 to 12
inches above 5000 feet, locally higher over peaks. Travel will be
difficult at times with hazardous conditions affecting the
morning commute and lesser so with the afternoon commute.

There will be brief lull in hazardous conditions with only light
precipitation expected early Friday morning with the next wave of
heavier precipitation expected Friday late morning through early
Sunday morning. Snow levels on Friday will be around 4000-5000
feet, up to 6000 feet south of Hwy. 50. On Saturday, snow levels
remain relatively the same with the areas south of 50 being closer
to 5500 by Saturday afternoon.

Totals with this wave are 0.75-2.50" in the Valley north of I-80
increasing as you move northward and 0.25-0.75" in the Valley
south of I-80. The mountains, foothills, and Northern Sacramento
Valley is forecasted to see 1.00-4.00", up to 7 inches across
northwestern Shasta county. Saturday morning will be the heaviest
period of this stretch, highest north of I-80.

Snow with this wave will be heavier than the first and see several
periods of heavy snow at times. Totals from Friday AM to Sunday AM
for the Sierra above 5000 feet are 12 to 24 inches, up to 3-4
feet along the higher peaks. For Shasta county, the mountains
will see 1 to 3 feet up to 5 feet along the higher peaks. Snow-
covered roads, chain controls, and travels delays will likely
result in very difficult travel at times. For Shasta county,
models show a 50-90% chance of 12 inches or greater of accumulated
snowfall over the mountains. For the Sierra, there is 50-80%
chance of 18 inches above 5000 feet. As we wind down with
the current event, we will provide updates to the winter headlines
to cover the next wave of snow for this weekend.

Lastly, strong winds will accompany our active weather beginning
in earnest Friday morning over the northeastern foothills and
Burney Basin and then spreading to the rest of the Valley and
Sierra on Saturday. On Friday, there is a 30-65% chance of gusts
greater than 40 MPH across the northeastern foothills and Northern
Sacramento Valley. Saturday will chances expand to much of the
forecast area with around a 50-90% chance, highest over the Sierra
crest and northeastern foothills. The EC Extreme Forecast Index
supports the development of stronger winds in the Valley as well
with an above normal wind forecast projected for the Central
Valley and adjacent foothills. As we continue through the event,
we will evaluate the need for any wind headlines with further
updates to the forecast.

Sunday morning will see everything taper off, outside of
lingering showers over the Sierra. This will be a more substantial
lull with the next round of active weather beginning on Monday
late morning. Afternoon highs will be fairly consistent with 50s
in the Valley and 30s to 40s across the mountains to foothills
respectively.

.EXTENDED DISCUSSION (Monday THROUGH Thursday)...

Another Pacific frontal system progged to move through interior
NorCal Monday into Tuesday. Widespread precipitation and some
gusty wind expected, but overall QPF looks less than the previous
weekend storm. Snow levels begin around 3500-5000 feet Monday,
rising to 4500-5500 feet Tuesday morning with potential snow
advisory amounts. Drying weather Tuesday with warmer temperatures
into Thursday with some locally gusty north to east wind as upper
ridging builds inland

&&

.AVIATION...

Widespread MVFR with areas IFR and lcl LIFR obscuring trrn next
24 hrs. Snow levels 4000-4500 feet. Sfc wind mainly at or below 12
kts in Central Vly with lcl gusts to 20 kts. Areas of S-SW wind
gusts up to 35 kts over higher trrn.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 4 PM PST this afternoon for Burney
Basin / Eastern Shasta County-Shasta Lake Area / Northern Shasta
County-West Slope Northern Sierra Nevada-Western Plumas
County/Lassen Park.

&&

$$