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fxus66 ksto 161119 
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Area forecast discussion
National Weather Service Sacramento California
319 am PST Sat Dec 16 2017



Synopsis...
a few light showers over the northern Sierra this morning. Windy
dry conditions today into tonight with wind advisories and red
flag warnings in place. Decreasing winds Sunday. A chance of light
rain or showers mainly over the mountains mid week. Otherwise dry
conditions through the end of next week.
&&

Discussion...
upper trough axis now making its was through the northern Sierra
with a few light showers showing up on radar. Only a few trace
amounts of precipitation have been reported. Clearing over the
Central Valley has allowed areas of fog to form there. Northerly
surface gradient is increasing and already over 10 mb from mfr to
SAC. Red Bluff is already seeing sustained winds of 20 knots.
Lighter north winds are occurring farther south and these winds
will be on the increase today as the upper level northerly flow
mixes down. Surface gradient maxes out this afternoon at over 15
mb from mfr to SAC. Predicted 925 mb winds are at 30-40 knots.
Strongest winds are forecast to be from the central Sacramento
Valley west and southward. Combination of low relative humidity and strong north
wind will reach red flag criteria over the Coast Range while the
strongest winds will occur down the Central Valley. Meanwhile,
cool advection will bring daytime highs down to near normal
despite clearer skies today. Surface gradients weaken overnight
but breezy north winds will continue. Lighter but still breezy
north winds will continue on Sunday and there will be warming as
the upper ridge axis centers over the West Coast. Warm conditions
and lighter winds continue Monday and Tuesday as the upper ridge
slides over the West Coast. An upper trough dropping out of the
Pacific northwest may bring a chance of rain to the northwest
corner of the state by Tuesday night or early Wednesday of next
week.

&&
Extended discussion (wednesday through saturday)

Confidence is improving that a cold upper trough from the Gulf of
Alaska will move through the region on Wednesday bringing the
potential for showers, mainly for the foothills and mountains.
Precipitation is expected to be minimal. Gusty north winds will
likely develop through the Central Valley in its wake later next
week.
&&

Aviation...

VFR conditions next 24 hours except local IFR/MVFR in fog and br in
the Central Valley south of ksmf til 16z. Northerly winds increase
in the Central Valley to 20-30 kts with gusts 30-40 kts by 18z.
&&

Sto watches/warnings/advisories...
red flag warning until 10 am PST Sunday 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.

Wind Advisory until 6 PM PST this evening for Carquinez Strait
and Delta-central Sacramento Valley-Clear Lake/Southern Lake
County-mountains southwestern Shasta County to Northern Lake
County-northern Sacramento Valley-northern San Joaquin Valley-

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