Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 141720
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
920 AM PST Thu Dec 14 2017

.Synopsis...
Weak system brings a slight chance of light showers over the
mountains Friday night into early Saturday, otherwise dry into
early next week with mild days and chilly nights. Breezy this
weekend with increased fire concerns.

&&

.Discussion...
Strong upper high continues along the West Coast resulting in a
period of prolonged dry weather with mild days and chilly nights.
Some patchy mist or light fog was reported around the Southern
Sacramento and Northern San Joaquin Valleys earlier, but had no
impact and was short lived. Mild temperatures forecast again
today with above normal highs.

Upper ridge begins to weaken Friday as short wave trough pushes
into the PacNW. Higher clouds and synoptic cooling will be on the
increase over Interior NorCal tomorrow. Main cooling will be felt
over the northern third of the CWA with temperatures nudging down
about 4 to 7 degrees.

Short wave trough digs through Interior NorCal Friday night.
System looks weak with limited available moisture, but models
suggest the potential for some light showers over the Shasta and
Plumas mountains, and possibly higher elevations of the Northern
Sierra Nevada. QPF looks light, less than a tenth of an inch and
little to no snow accumulations are expected.

Surface and upper ridging build back inland behind this wave on
Saturday resulting in breezy conditions over Interior NorCal.
Gusty north to east wind will occur with lowering humidity. This
will result in increased fire weather concerns, and a Fire
Weather Watch may be issued today. Wind speeds at this time look
to be mostly below wind advisory criteria but isolated spots may
reach into lower limits of advisory. Strongest winds are expected
along the west side of the Sacramento Valley. Locally gusty
northeast to east wind can also be expected through the NE
foothills and motherlode and west slopes of the Northern Sierra
Nevada. Breezy conditions continue into Sunday. High temperatures
over the weekend will be in the 60s for the Central Valley, with
40s to lower 60s for the mountains and foothills.

PCH

&&

.EXTENDED DISCUSSION (Monday THROUGH Thursday)
High pressure will continue to bring mild daytime temperatures
and cool overnight lows through early next week. Models have come
into to agreement with a cold Pacific storm system dropping south
mid-week. This system breaks down the ridge rather rapidly and
brings a few impulses of precipitation across Northern California.
Have introduced precip chances Wed-Thur to reflected possible
pattern change. This is the first run of model agreement(GFS/Euro)
and relatively low confidence remains.

&&

.AVIATION...

VFR conditions across Interior NorCal the next 24 hours except
isold MVFR/IFR conditions in BR/FG for the southern Sacramento
and northern San Joaquin Valleys after 09z Thursday. Valley winds
generally below 10 knots.

Dang

&&

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

$$


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