FXUS66 KSTO 071154
AFDSTO
Area Forecast Discussion
National Weather Service Sacramento CA
354 AM PST Thu Dec 7 2023
Synopsis...
Rain showers spread into the area through today with moderate
mountain snow expected into this evening, with gusty winds for
higher mountains. Expect breezy southerly winds for portions of
the Valley today and then northerly winds Friday. Drier
conditions and increasingly cold temperatures are expected Friday
into the weekend.
A shortwave with a cold front brought some heavier convective
snow showers through the Sierra in the evening yesterday,
bringing chain controls and travel delays at times. Lingering snow
showers continue this morning over the mountains, mainly over the
northern Sierra. Cold air behind the front is allowing snow
levels to drop to around 4,000-4,500 feet. There are gusty winds
being observed over mountain ridges, up to around 40-45 mph.
There will be a bit of a lull in area precipitation this morning,
before the next wave moves into northwestern California and
spreads southeastward through the area today. Light rain is
expected to develop across the Valley, Delta and foothills by
afternoon. Snowfall will increase again over the mountains, with
snow levels remaining around 4,000-4,500 feet. A Winter Weather
Advisory continues through 10 PM PST tonight for the mountains of
eastern Shasta County, western Plumas County/Lassen National
Park, and the west slopes of the Northern Sierra Nevada, including
I-80 and Hwy 50. This next system is not expected to be as
convective, but there could be moderate snow at times. Heaviest
snow is expected around 2 to 6 pm PST, with the NBM mean snow
rates projecting up to an inch an hour. Along with the snow, gusty
winds will continue over higher terrain, and when coupled with
snow could bring poor visibility at times. These conditions will
impact mountain travel, so use caution while traveling over this
period. Additional snowfall of around 4 to 8 inches is expected
above 5,000 feet.
Valley rain showers wind down around the evening commute, with
snow showers lingering a little longer over the mountains. Dry
conditions are expected across the area after midnight as high
pressure ridging builds in. Dry weather is expected for Friday,
Saturday, and much of the area Sunday. A shortwave brushing by
to the north Sunday could bring some showers to portions of
Shasta County, though.
There will be some breezy southerly winds today in the Valley,
gusting up to 20 to 30 mph over the northern and central
Sacramento Valley. Winds in the Valley will shift to the north Friday
morning and afternoon with, with wind gusts to 15 to 30 MPH,
potentially chilly tapering off Friday night. Temperatures will
generally be in the 50s and warmer as you move southward in the
Valley with 40s and 30s over the foothills and mountains. Saturday
and Sunday mornings could be cold with morning lows in the low to
mid 30s from Red Bluff to Modesto, with areas of frost. //EK
.EXTENDED DISCUSSION
(Monday THROUGH Thursday)...
Weak short wave trough progged through interior NorCal Monday,
but associated moisture looks limited and forecast remains dry.
Trough pushes into the Great Basin Monday night as high amplitude
upstream upper ridge builds inland. This will result in some gusty
north to east wind the continue Tuesday into early Wednesday.
Confidence lowers midweek as models differ with progression of
next upstream short wave trough. Forecast remains dry through the
extended at this time with high temperatures slightly above
normal.
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