Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 142217

Area Forecast Discussion
National Weather Service Reno NV
217 PM PST Thu Dec 14 2017


Temperature inversions and reduced air quality in urban valleys
continue through Friday afternoon, with a weak system Friday
night increasing surface winds and bringing improved air quality
for the weekend. Inversions are likely to strengthen again early
next week before a cold front moves through for the middle of next
week and breaks the inversions.



Beefed up winds in Sierra Saturday into Sunday morning, otherwise
little change to the short term forecast.

Temperature inversions continue today and are expected to weaken
Friday night and Saturday as a fast-moving shortwave moves through
northeast California and western Nevada. Better mixing and
increasing northerly low level winds should be enough to allow for
increasing air quality going into the weekend.

This system has very little moisture associated with it and is
forecast to begin shearing/splitting as it moves through central
California. The best precipitation chances in early morning
simulations are in far northwest and north-central Nevada behind
the cold front; however, some late morning simulations indicate a
narrow precipitation band moving down to between Pyramid Lake and
I-80 in far western Nevada. Dry air ahead of the cold front will
help snow levels drop quickly to valley floors, but with the lack
of moisture (less than 0.10" of precipitation in most
simulations), little (less than 1/2") to no snow accumulation is
expected for most areas. Still, be alert if traveling early
Saturday as even light snow showers overnight could bring a thin
layer of patchy ice as temperatures fall to near or below freezing
Saturday morning.

One other item of note will be strengthening easterly winds over
Sierra ridges for the weekend as high pressure rebuilds into the
Great Basin. The depth of the colder air intrusion and strength of
winds aloft should be sufficient to bring increased winds on Lake
Tahoe by Saturday afternoon, likely lasting into Sunday morning.
The winds are likely to cause issues for small craft on the lake,
especially for mid-lake and western shores where waves will be
highest. -Zach/Snyder

.LONG TERM...Monday onward...

High pressure returns for early next week resulting in poor mixing
and ventilation again for Monday and Tuesday. Haze may once again
form mainly near population centers as well.

Simulations continue to show a strong cold front moving southward
through the area Wednesday with some much colder air spreading into
the Sierra and western Nevada. Low chances for showers remain for
Wednesday along this front. The storm doesn`t have a significant
moisture tap, but it will require monitoring since it will be so
cold. The very cold nature of the storm may result in snow even down
to valley floors. The air behind this front will be some of the
coldest we have seen so far and it could linger into the weekend
right ahead of Christmas. Hohmann/Edan



Mainly VFR with light winds (less than 8-10 kts) for valleys through
Friday morning.

Valley inversions will remain strong through Friday, resulting in
slantwise visibility concerns for lower valleys, especially in the
Reno/Sparks, Carson City, and Minden areas. Increased northerly
winds Friday night and Saturday may allow some of the haze to
clear out, at least for a day or two. -Edan/Hohmann


.REV Watches/Warnings/Advisories...


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