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374
FXUS66 KSTO 082234
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
234 PM PST Sun Dec 8 2019

.SYNOPSIS...
Lingering rain and mountain snow showers continue this afternoon,
with drier weather returning late this evening. High pressure
builds over the region on Monday, which will lead to a period of
dry conditions and near average temperatures. More widespread
precipitation could return late in the week.

&&

.DISCUSSION...
Water vapor imagery and mid-level height fields show a
positively-tilted trough slipping southward through central
California. Cool temperatures aloft combined with daytime heating
has fueled scattered showers generally south of Highway 50. A few
of the more robust cells may produce a rumble of thunder or two.
Across the higher terrain, generally above 5,500 feet, any such
snow shower may briefly reduce visibilities. All of this activity
should wind down by the evening hours as the upper low shifts
farther south along with the loss of diurnal heating. Some
residual cloud cover will likely linger into the evening with
skies gradually clearing overnight. At this point expecting
Valley fog to form given the level of moisture sitting on the
ground and in agriculture. This would include the Sacramento and
northern San Joaquin Valleys with any fog likely mixing out by
mid/late Monday morning.

Heights will continue to build on Monday as an offshore ridge
moves through. This ensures a period of dry weather to start the
week with near average temperatures. The ridge axis crosses the
state early Tuesday before a weak shortwave enters the picture for
Tuesday evening into the following morning. Moisture seems to be
meager so precipitation will be light, mainly focused over the
northern Sacramento Valley and into the higher terrain. Any
snowfall will lead to little to no accumulations. Lingering
precipitation should diminish by midday Wednesday with the trough
shifting into southern Nevada. ~BRO
&&

.EXTENDED DISCUSSION (Thursday THROUGH Sunday)...
We will see zonal flow for the start of the extended period. A
short wave tracking into the PacNW Thursday will push a cold front
into the region. This will bring the chance for some light
showers over the higher elevations with the best chances north of
I-80. Snow levels will be high and most of the activity will fall
as rain. A stronger trough will dig into the area on Friday.
Ensembles are in pretty good agreement with pushing a cold front
south through the area Friday night. This will be the best chances
for widespread precip activity. The trough axis will then push
through on Saturday and this is going to keep widespread shower
activity in the mountains throughout the day. Snow levels start
out well above pass level but will be falling on Saturday and we
could see some light snow down to pass level Saturday afternoon.
We also could see breezy southerly winds Saturday
morning/afternoon as the trough pushes east through the area.

Short wave riding builds in on Sunday and continues into Monday
with dry weather expected. Temperatures will mainly be near
average throughout the period.

-CJM

&&
&&

.AVIATION...
Scattered showers will be possible for KSCK and KMOD until 23z.
MVFR conditions are expected until 23z for southern terminals due
to low cigs, locally lower vis and cigs in any showers. Skies
clear overnight with fog developing KMYV south. Low vis is
expected from 10z to 17z brining widespread MVFR conditions with
localized IFR. Winds remain under 10 knots. &&

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

$$