Challenge, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

531
FXUS66 KSTO 040917
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
117 AM PST Wed Dec 4 2024

.SYNOPSIS...
Areas of low elevation morning fog persist through much of the
week ahead alongside otherwise dry and gradually warming weather.
More seasonable temperatures and breezier winds then expected
through the weekend into early next week.

.DISCUSSION...
As of early this morning, GOES-West satellite imagery shows clear
skies across interior NorCal as ridging aloft continues to
amplify over the Pacific Northwest. Despite this depiction, some
visibility obstructions (as low as 0.5 miles) have been noted
throughout the Valley from around Marysville southward via latest
surface observations as of 1 am PDT. With another night of
radiational cooling coupled with a slightly moistened boundary
layer, areas of low elevation fog are expected to continue through
mid morning. Current probabilities of visibility less than 1 mile
throughout the Valley sit around 20% to 40%, primarily focused
along the Interstate 5 and Highway 99 corridors.

As daytime heating further widens the dewpoint depression spread,
morning fog should start to dissipate by mid to late morning.
Despite the amplifying ridge to the north, the weather pattern is
expected to remain largely unchanged across interior NorCal today.
High temperatures in the 60s to are anticipated across the Delta,
Valley, and foothills, with 50s to low 60s at higher elevations.
Downslope winds look to remain breezy along the higher elevations,
with generally light north to east winds expected elsewhere.

The forecast for Thursday and Friday will be more or less of a
rinse, wash, and repeat with low elevation fog and breezy
downslope winds at higher elevations through the overnight and
morning hours giving way to slightly above normal high
temperatures and light winds through the daytime hours. Moving
into the weekend, a shortwave trough looks to move onshore near
the Pacific Northwest mid to late day Saturday. While appreciable
impacts across interior NorCal will remain limited, this should
work to weaken the ridging aloft and result in a cool down back to
near normal temperatures. A stray Shasta County shower cannot be
completely ruled out on Saturday, but probabilities of reaching
0.01 inches of precipitation only sit around 5% to 15% at this
time.

.EXTENDED DISCUSSION (Sunday THROUGH Wednesday)...
Upper ridging builds inland Sunday into Monday with some gusty
north to east wind. Pressure gradients relax Tuesday morning, but
tighten again over the northern and eastern foothills and
mountains Tuesday night into Wednesday morning and again Wednesday
night into early Thursday. NBM advertising some precip chances
over northern portions of the CWA Wednesday, but forecast
confidence is low with this as deterministic models maintain upper
ridging.

&&

.AVIATION...
Areas of MVFR with lcl IFR/LIFR possible in BR/FG in S Sac/N San
Joaquin Vlys til 18z and again aft 07z Wed, otherwise VFR next 24
hrs. Sfc wind generally below 12 kts except lcl N-E sfc wind up to
20 kts with gusts up to 30 kts in N and E foothills/mtns til 18z.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$