Area Forecast Discussion
Issued by NWS Reno, NV

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000
FXUS65 KREV 122134
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
134 PM PST Tue Dec 12 2017

.SYNOPSIS...

High pressure will continue to bring dry conditions along with
valley inversions, cold nights, and light winds for the next
several days. Localized air quality issues are possible due to the
strong inversions. Inversions should ease by the end of the week
as a weak cold front brushes the Oregon border, but no
precipitation is expected. A pattern change is looking likely by
the middle or end of next week.

&&

.DISCUSSION...

Mild days and cool nights will continue as a ridge of high pressure
remains in place. The 12z sounding only indicated the inversion has
strengthened, with obs at 8000-9000 feet nearly 50 degrees this
morning, while valleys were in the teens and single digits. Air
quality continues to be impacted, however the latest information
indicates most locations are in the moderate category with a
voluntary no burn in place. For the latest information in your
area, check with your county or airnow.gov. If you feel especially
parched, it`s not your imagination, the airmass is extremely dry
with 12z sounding PWAT values of 0.07. This is a record low value
for today`s date based on 20 years of sounding climatology data
from KREV.

A shortwave brushing by through the northwest and into the northern
Rockies Friday into Saturday will help to flatten and retrograde the
ridge westward. This is likely to increase winds and help with
mixing Friday into Saturday. Winds are not particularly strong, but
should increase just enough that in combination with cooling aloft,
inversions could mix out. This should help to improve air quality
and also allow for warmer daytime high temperatures in valley
locations. Precipitation doesn`t look promising, but can`t rule
out a few sprinkles near the Oregon/Idaho border late Friday into
Saturday morning.

With the ridge retrograded and amplified over Alaska, and a
weakening of the east coast trough, longer range guidance is
suggesting a colder pattern for the west coast. There are no hints
of any atmospheric river type moisture taps in the next two weeks,
but colder Pacific storms become a possibility by the end of next
week. Granted, there is a significant amount of spread in
forecast guidance, but it`s at least a glimmer of hope in this
current blocked pattern. -Dawn

&&

.AVIATION...

Mild and dry conditions continue with a ridge of high pressure
overhead. Light easterly flow can be expected with high pressure
centered over the Great Basin. Inversions are keeping haze trapped
in lower valleys with minor slantwise visibility reductions the next
several days. Some improvement looks likely by Friday with
increasing westerly flow. -Dawn

&&

.REV Watches/Warnings/Advisories...
NV...None.
CA...None.
&&

$$

For more information from the National Weather Service visit...
http://weather.gov/reno



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