Twain Harte, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

574
FXUS66 KSTO 262240
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
240 PM PST Thu Dec 26 2024


.SYNOPSIS...
Active weather will bring rain, mountain snow, and breezy to
gusty southerly winds into the weekend. Drier weather is expected
into next week.

&&
.DISCUSSION...
Cloudy skies are being observed across the area with just some
scattered showers, mainly over the mountains. Snow levels are
gradually rising, currently around 6,500 to 7,000 feet. At 2 pm
there were some chain controls at pass levels. For current road
conditions go to quickmap.dot.ca.gov. The best moisture with this
system so far has been favoring the northern mountains and
northern Sacramento Valley.
While there is a bit of a lull in precipitation this afternoon as
the first of a series of waves is exiting the area,another is
quickly moving in behind it this evening and continuing overnight
into early Friday. heaviest precipitation will be overnight. A
Winter Weather Advisory remains in effect for the northern Sierra
and the mountains of Plumas County and Lassen Park through noon
Friday for snow and gusty winds for elevations above 6,000 feet.
Around 4 to 12 inches total are expected. Snow levels should
linger around 6,500 to 7,000 feet through around 09Z, then rise
above pass levels, to around 8,000 feet Saturday morning. Periods
of heavy snow are possible, with a 30 to 60 percent chance of
snowfall an inch or more an hour at times. Locations near the
crest could see winds gusting to 55 mph overnight, and this with
heavy snow could bring poor visibility. Motorists should avoid
travel over passes overnight, if possible.

The associated moisture plume with this next wave is projected to
take a slightly further southward trajectory, resulting in a
better opportunity for more widespread precipitation into Friday.
The NBM projects rainfall from around a half inch to an inch for
the Valley and Delta.

In addition to precipitation, gusty winds are expected in the
VAlley. Southerly winds are expected to gust up to 25 to 45 mph
with the strongest winds from around Yuba City to near Redding.
This is due to a fairly strong low level jet over the area and a
fairly tight surface STDAFDSTOpressure gradient. A Wind Advisory
has been issued for 10 PM tonight to 10 AM tomorrow for the
northern and central Sacramento Valley. Winds gradually diminish
Friday afternoon.

The active weather period then looks to continue across interior
NorCal into the weekend underneath broad northwesterly flow aloft.
This flow pattern will allow another shortwave ejection, similar
to today`s system, into the region. As a result, the majority of
precipitation on Saturday is expected from Interstate 80 northward
at this time. Probabilities of exceeding 0.5 inches of liquid
precipitation around 60% to 80% favor the northern Sacramento
Valley and surrounding terrain and the Sierra/southern Cascades
north of Interstate 80, with probabilities generally less than
20%. elsewhere. Given high expected snow levels above 8000 feet,
only light accumulations at peaks are expected on Saturday.

On Sunday, yet another push of moisture will bring more rain and
colder air. Snow levels will initially sit around 7000 feet
before lowering that afternoon to 5000 to 6000 feet by Sunday
evening. Currently there is a 30 to 60% chance of snow
accumulations exceeding 4.00 inches. Highest rainfall
accumulations will once again be over Shasta County and the
foothills/mountains.

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


.EXTENDED DISCUSSION (Monday THROUGH Thursday)...
Models showing interior NorCal will be under the influence of
upper level ridging through the extended forecast period. High
temperatures will be near to slightly above normal with chilly
nights. There is the potential for some patchy overnight fog or
frost in the Central Valley. The best potential for frost is
Tuesday morning. The NBM showing is potential for some
precipitation returning over northern portions of the area into
Thursday, however confidence in this remains low.

&&

.AVIATION...
Areas MVFR/IFR with local LIFR possible in precip and/or low
ceilings, becoming more widespread 00z-16z Friday. Snow levels
5500-6500 feet rising to 7000-8000 feet after 06z Friday.
Widespread southerly surface winds 15-25 kts with areas of gusts
to 30-35 kts in the Valley 04z-18z Friday. Over mountains, areas
of southwest to west surface wind gusts 30-40 kts increasing to
35-50 kts after 06z-18z Friday.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
Wind Advisory from 10 PM this evening to 10 AM PST Friday for
Central Sacramento Valley-Northern Sacramento Valley.

Winter Weather Advisory until noon PST Friday for West Slope
Northern Sierra Nevada-Western Plumas County/Lassen Park.

&&

$$