Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 141122

Area Forecast Discussion
National Weather Service Reno NV
322 AM PST Thu Dec 14 2017


Temperature inversions, cold nights, and light winds continue through
Friday, with reduced air quality in urban valleys. A weak system
Friday night will increase surface winds and break the inversion
bringing improving air quality for the weekend. Inversions are
likely to strengthen again early next week before a colder system
moves through midweek.



Increasing temperature and pressure gradients pushed northeast wind
gusts up to 70 mph along the Sierra crest overnight with 15 to 20
mph winds mixing down to the west side of Lake Tahoe. Gradients
will weaken today with winds in the upper elevations becoming
light by late afternoon as the wind changes back to a westerly
direction tonight.

Temperature inversions continues today and are expected to break
by Saturday as fast moving shortwave moves through the region.
Better mixing and increasing northerly surface winds should be
enough to allow for increasing air quality going into the weekend.

This pattern is what is sometimes referred to as an "outside
slider" since the area of low pressure moves from north to south
along the west slope of the Sierra. This system has very little
moisture associated with it and is forecast to split as it moves
through central California further decreasing it`s precipitation

While the low passes through central California the best
precipitation chances will remain in north central Nevada behind
the cold front. For the Sierra and western Nevada Total QPF from
the system is forecast to be less then 0.10" for most areas. Dry
air ahead of the cold front will help snow levels drop quickly to
valley floors, but with the lack of moisture, little to no snow
accumulation is expected for most areas. -Zach

.LONG TERM...Sunday onward...

A flat ridge of high pressure will develop and persist through at
least the first part of Tuesday. Mixing and ventilation will once
again decrease with the worst conditions Monday into Tuesday. Haze
may once again form mainly near population centers although the
duration and strength of this upper ridge will be less than the
current high pressure system.

High pressure is forecast to amplify over the east Pacific for mid
to late next week which will turn the flow aloft to the north out of
Canada. Both the 00Z GFS/ECMWF show a strong cold front moving
southward through the area Wednesday with some much colder air
spreading into the region. We have introduced some low chances for
snow showers Wednesday along this front and while not a big storm,
it will bear watching due to its cold nature and potential to bring
some snow even 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



Mainly VFR with light winds (less than 8-10 kts) for valleys through
at least Friday morning. However, gusty easterly winds will continue
this morning over the Sierra crest as high pressure strengthens in
the Great Basin. Gusts 30-45 kts are likely to bring light to
moderate turbulence over and west of the Sierra crest into early
this afternoon.

With valley inversions remaining strong through Friday, slantwise
visibility will remain degraded during the daylight hours for lower
valleys, especially in the Reno/Sparks, Carson City, and Minden
areas. Increased northerly winds Friday night and Saturday should
clear much of the haze out, at least for a day or two.


.REV Watches/Warnings/Advisories...


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