Area Forecast Discussion
Issued by NWS Reno, NV

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000
FXUS65 KREV 112142
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
142 PM PST Mon Dec 11 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.

&&

.DISCUSSION...

Mild days and cool nights will continue as a ridge of high pressure
remains in place. This morning`s low temperatures were a perfect
example of the inversion -- most valleys were in the teens and
single digits while midslopes and ridges above the inversion had
lows in the mid 30s to low 40s! Guidance is actually suggesting
slightly cooler temps the next couple of nights, despite the airmass
really not changing much. The likely reason for this is the
extremely dry air mass overhead, which is only progged to dry
further. PWAT values (the amount of liquid in a vertical
column) are near climatological record lows, allowing for
excellent radiative cooling at night.

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 would mix out. This should help to improve air quality
and also allow for warmer daytime high temperatures. Depending on
the extent of the mixing, near record high temperatures are not
out of the question Friday afternoon. 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, 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...

Minimal weather impacts for flying this week. Bone dry airmass for
early winter with near record low moisture values through Wednesday.
High pressure over the Great Basin yielding light east northeast
flow. Storm track remaining well to our north or far offshore.
Valley inversions at RNO, CXP will trap haze resulting in reduced
slantwise visibility, maybe to MVFR especially if looking toward the
suns general direction.

-Chris

&&

.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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