Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 141030
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
330 AM PDT Sat Oct 14 2017

.SYNOPSIS...
Dry weather continues into early next week. Gusty north winds
will today with critical fire weather conditions expected. Chance
of rain arrives late next week.

&&

.DISCUSSION...
Heightened fire weather concerns as northerly winds increase
across interior NorCal behind the trough moving east. Water vapor
imagery shows darkening associated with increasing subsidence
moving south across the region at the same time as north and east
surface gradients are increasing (MFR-SAC approaching 12 mbs and
RNO-SAC over 6 mbs). Gusts of 20-30 mph common now along the west
side of the Sacramento Valley while some foothill and mountain
areas are seeing gusts of 30-40 mph. KDAX VWP indicating 50 knots
at 1-2K ft.

Models indicate barrier jet along the west side of the Sacramento
Valley maxes out around 12Z-15Z (focused into western Yolo and
southern Lake Counties), then weakens this afternoon. Weaker
barrier jet redevelops tonight into early Sunday.

Lighter winds with slight warming in temperatures expected early
next week.

&&

.EXTENDED DISCUSSION (Wednesday THROUGH Saturday)
An upper level low pressure system begins to approach Tuesday,
allowing daytime temperatures to cool back to near normal Tuesday
into Wednesday. Models in continued agreement that this trough
will create an unsettled weather pattern midweek into the weekend,
bringing decent chances for much needed precipitation to NorCal.
Precipitation chances forecast to begin overnight Wednesday for
areas mainly north of the Sacramento area. As the trough deepens
Thursday into Friday, increased chances of precipitation sweep
over the entire interior NorCal area. Daytime temperatures
expected to cool to around 5 degrees below normal in the southern
Sacramento valley down to 15 degrees below normal in the northern
Sacramento valley and mountains. Snow levels expected to drop to
about 6000 ft to 7000 ft by Thursday night. Light snow
accumulations expected at higher elevations. HEC

&&

.AVIATION...
VFR conditions for the next 24 hours with northerly afternoon
gusty winds today. Stronger north to northeast wind increases
tonight with gusts in the 30 to 35 kt range for Coastal Range and
Sierra ridgetops, and similar wind speeds across northern and
western Central Valley by Saturday morning. JClapp

&&

.STO WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until 8 AM PDT Sunday for Carquinez Strait and
Delta-Central Sacramento Valley in Glenn, Colusa, Yuba, Northern
Sutter, and Butte County Below 1000 Ft-Eastern Mendocino NF-
Eastern Portion of Shasta/Trinity NF-Lake County Portion of Lake-
Napa-Sonoma Unit-Northern Motherlode From 1000 to 3000 Ft.
Includes portions of Nevada-Yuba-Placer-Amador and ElDorado
Units-Northern Sacramento Valley to Southern Tehama County Line
Below 1000 Ft-Northern Sierra Foothills from 1000 to 3000 Ft.
Includes portions of Shasta-Trinity and Butte Units-Northern
Sierra Including Lassen NP and Plumas and Lassen NF/S West of
the Sierra Crest (West of Evans Peak-Grizzly Peak-Beckworth
Peak)-Northern Sierra Including the Tahoe and ElDorado NF/S West
of the Sierra Crest-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-Stanislaus NF West of the Sierra Crest.

Wind Advisory until 5 PM PDT this afternoon for Carquinez Strait
and Delta-Central Sacramento Valley-Clear Lake/Southern Lake
County-Northern Sacramento Valley-Southern Sacramento Valley.

&&

$$



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