Rosemont, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

392
FXUS66 KSTO 262200
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
200 PM PST Tue Nov 26 2024


.SYNOPSIS...
Precipitation across interior NorCal tapers off by this evening,
with lingering showers until early Wednesday morning. Dry
conditions are expected for Thanksgiving through the holiday
weekend, with cold, frosty mornings.

.DISCUSSION...
The last of a series of shortwave troughs will exit the area to
the southeast by this evening. Precipitation has tapered off with
some lingering light showers continuing across mountains and
foothills this afternoon, with enough instability over Shasta
County to see a few isolated thunderstorms. Lightning detection
and radar showed a weak thunderstorm develop early this afternoon
just northwest of Fall River Mills. The HRRR model suggests a few
more convective cells could form north and east of Redding through
4 pm. The latest satellite loop shows skies largely clearing in
the Sacramento Valley north of I-80. Much of the rest area is
expected to gradually clear overnight. With a fairly quick exiting
of this system, winter weather concerns will be winding down by
this evening, so the Winter Storm Warning for the West Slope of
the Northern Sierra Nevada and for western Plumas County/Lassen
Park now ends at 4pm.

High pressure ridging builds in on Wednesday bringing dry and
mostly sunny conditions through the holiday weekend. Breezy north
to northeast winds should limit fog development Wednesday
morning, but with lingering low level moisture and clear skies
can`t rule out some patchy developing, mainly for sheltered areas
in the eastern portion of the northern San Joaquin Valley. These
winds continue overnight into Thursday and could limit morning
temperatures from getting very cold. The NBM currently shows a 20
to 70% probability of reaching 36 degrees or less for the Valley
on Wednesday, highest on the east side of the Valley. This is the
temperature when frost typically becomes and issue. Some lower,
sheltered areas could see below freezing. Thursday and Friday are
expected to be colder, with a 40-95% chance of lows 36 or below,
again mainly on the east side of the Valley. These cold
temperatures could impact pets, plants, and those without adequate
heating. Prepare for widespread frost. Running events on
Thanksgiving could also be impacted, so if you are a participant
or spectator make sure to dress for cold weather.

.EXTENDED DISCUSSION (Saturday THROUGH Tuesday)...
Ensemble guidance is in generally good agreement on the upper
level pattern through the weekend and into early next week.
Ridging is expected to build over the Pacific Northwest and over
top of a closed low off shore of SoCal, leaving interior NorCal
underneath split flow aloft. Although, there are some notable
discrepancies regarding the strength and persistence of the closed
low. While some ensemble members indicate a few subtle shortwave
ejections from the semi-stalled offshore low, a lack of
appreciable moisture advection into interior NorCal will likely
limit any precipitation potential across the region. Given the
anticipated pattern shift, more or less seasonable temperatures
are anticipated across the extended forecast period, although
Saturday morning low temperatures may still linger in the low to
mid 30s alongside attendant low elevation frost potential.
Otherwise, light to breezy northerly winds are expected across the
Valley and foothills with breezy to occasionally gusty easterly
winds along the Sierra, with gusty winds contingent upon any
shortwave ejections.

&&

.AVIATION...
VFR conditions expected for Valley/foothills locations of
interior NorCal next 24 hours. MVFR/IFR conditions persist in
mountain snow showers through 00z, improving to primarily VFR
after. Generally light and variable Valley/foothills winds today
become breezy up to 12 kts from the north after 06z, with some
gusts up to 25 kts across the Delta. Westerly gusts to 30 kts
along the Sierra continue through 06z, shifting to easterly
downslope winds overnight.


&&

.STO WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning until 4 PM PST this afternoon for West
Slope Northern Sierra Nevada-Western Plumas County/Lassen Park.

&&

$$