Area Forecast Discussion
Issued by NWS Sacramento, CA

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505
FXUS66 KSTO 221109
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
309 AM PST Wed Nov 22 2017


.SYNOPSIS...
Mild temperatures this week, with weak weather systems possible on
Thanksgiving and Saturday. Colder weather system early next week.

&&

.DISCUSSION...
Dry weather continues across interior Northern California today
with strong high pressure to our south. Some high cloudiness is
spilling over the top of the ridge, but hasn`t prevented areas of
fog formation across much of the region`s valleys. Many
observation sites have been reporting quarter-mile or less
visibilities across the Central Valley, and GOES16 satellite
products show these areas of fog expanding overnight. As such, a
Dense Fog Advisory has been issued for the Sacramento and Northern
San Joaquin Valleys through late morning. Fog may be slow to burn
off today, which may help to suppress afternoon temperatures.

The stream of moisture currently off the California coast will
finally push inland on Thanksgiving, weakening as it does so. A
few showers and a bit of cooling is expected, but shouldn`t be a
significant impact to holiday activities.

Dry weather returns on Friday. The GFS and ECMWF have begun to
hint at a shortwave moving through Northern California Saturday,
possibly into Sunday. Forecast confidence is low on the timing and
intensity of this weather system.

Dang

&&
.EXTENDED DISCUSSION (Sunday THROUGH Wednesday)

Weak shortwave will pass through the area early Sunday ahead of a
larger low pressure system and associated trough. This will bring
some showers to the area, with majority of the activity expected
over higher elevations. Snow levels with this initial wave look to
be above pass levels, so minimal impacts. Aforementioned low
pressure system will then swing through the area later Sunday into
Monday. Models have sped up timing a bit since yesterday, with
precipitation occurring overnight before likely tapering off
Monday morning. System doesn`t look overly wet with a tenth to
half inch in the valley and up to 1.25 inches at higher
elevations. As colder air wraps in, snow levels will drop below
pass levels Sunday night, down to around 4000-5000 feet Monday
morning. Several inches of snow accumulation possible at pass
levels which could be enough to cause a few delays overnight
Sunday into Monday. Dry weather returns for Tuesday into mid-week
as ridging builds into the area.

CEO

&&
&&

.AVIATION...

Fog developed overnight in the valley with areas of dense fog at
majority of the terminals. Expect IFR/LIFR conditions through the
morning hours with improving conditions during the day. Winds
under 10 kts.

&&
&&

.STO WATCHES/WARNINGS/ADVISORIES...
Dense Fog Advisory until 11 AM PST this morning for Carquinez
Strait and Delta-Central Sacramento Valley-Northern Sacramento
Valley-Northern San Joaquin Valley-Southern Sacramento Valley.

&&

$$



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