Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 142255
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
255 PM 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 through
early next week. Breezy to windy conditions forecast this weekend,
resulting in increased fire concerns.

&&

.Discussion...
Strong upper high along the West Coast will weaken Friday as a
short wave trough pushes into the PacNW. Some patchy mist or light
fog will be possible in the Southern Sacramento and Northern San
Joaquin Valleys tomorrow morning. This will be short lived and
have no real impact. Higher clouds will be on the increase over
Interior NorCal Friday. Some synoptic cooling will occur over
northern portions of the CWA tomorrow 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 with
little to no snow accumulations expected.

Surface and upper ridging builds back inland behind this wave
late Friday night into Saturday. Strong pressure gradients
develop overnight, leading to breezy to windy conditions
across Interior NorCal. Latest model guidance is suggesting wind
speeds into advisory criteria Saturday across portions of the
Central Valley, especially over the western half extending into
the Coastal Range. Gusty wind will lower humidities, and with dry
fuels in place, will lead to increased fire potential. Fire
Weather Watch has been issued to address this. Wind Advisory
likely to be issued Friday if models continue stronger wind
scenario. In the eastern foothills and mountains, locally gusty
northeast to east wind can be expected. Breezy conditions continue
on 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 second run of model
agreement(GFS/Euro) and relatively low confidence remains.

Shoe/Dang

&&

.AVIATION...

VFR/MVFR conditions across interior NorCal the next 24 hours
except local MVFR/IFR conditions in BR for the southern Sacramento
and northern San Joaquin Valleys. Valley winds generally below 10
knots.

Shoe/Dang

&&

.STO WATCHES/WARNINGS/ADVISORIES...
Fire Weather Watch from Friday evening through Sunday morning
for Carquinez Strait and Delta-Central Sacramento Valley in
Glenn, Colusa, Yuba, Northern Sutter, and Butte County Below
1000 Ft-Eastern Mendocino NF-Lake County Portion of Lake-Napa-
Sonoma Unit-Northern San Joaquin Valley in San Joaquin and
Stanislaus Counties Below 1000 ft-Southeast Edge Shasta-Trinity
NF and Western Portions of Tehama-Glenn Unit-Southern Sacramento
Valley in Yolo-Sacramento Far Western Placer, southern Sutter
and Solano County Below 1000 Ft.

&&

$$


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