Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 152158
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
158 PM PST Fri Dec 15 2017

.SYNOPSIS...

A weak system moves through the region tonight increasing surface
winds and bringing improved air quality for the weekend. Some road
surfaces may be a little slick Saturday morning due to very light
snow accumulations. Otherwise, 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.

&&

.SHORT TERM...

Changes to the forecast were minor. A weak slider-type system will
move through the region tonight through Saturday morning. Timing
remains unchanged; a brief and light pre-frontal band of
precipitation is expected late this evening and the frontal band
itself can be expected from around midnight through around dawn
this morning. This puts precipitation in the Reno area
(rain/rain-snow mix) around 10 pm this evening and again from
around 2-4am (predominantly snow).

Accumulations are expected to be very light area-wide with
generally a dusting to about a quarter of an inch. Still, even
this small amount will allow for slick conditions around the
region Saturday morning. Some favored upslope locations and areas
just downwind of Lake Tahoe and Pyramid Lake may see up to 1 inch
from a slight lake enhancement. The fast translational speed and
relative dryness of this system are the major limiting factors for
snow accumulations.

Winds shift northerly behind the system by late Saturday morning.
It will feel brisk out there with northerly flow switching
easterly and gusts around 15-25 mph. Ridging returns by Sunday
while flow remains easterly. Sierra Crest winds will likely remain
quite gusty under this flow regime through early Sunday since the
thermal gradient remains tight.

Temperatures turn colder for the weekend with western Nevada highs
struggling in the upper 30s and Sierra valleys in the low/mid 30s.
Overnight lows dip back to the upper teens/low 20s with single
digits for colder Sierra valleys as well as colder valleys in the
Basin and Range. Boyd

.LONG TERM...Monday onward...

A weak amplitude ridge will be in place early next week which will
again provide dry conditions, light winds, and valley inversions.
However, models do continue to show a potential for a more potent
slider type system on Wednesday.

A strong cold front along with strong winds look to accompany the
slider through the northern Sierra and western Nevada on Wednesday.
The cold airmass behind the front should lower snow levels to all
valley floors by Wednesday afternoon with accumulating snowfall
possible. Models show good agreement in pushing this system through
the area, but as typical with slider systems, the uncertainty will
be with timing and intensity. Nonetheless, this system has been
showing good instability and frontal forcing along with more
moisture when compared to this weekend`s system so travel impacts
could be a bit more widespread. This system is a fast mover and
should aid in limiting precipitation totals.

As this system departs, we will develop another period of gusty
northeast winds across the ridges by Thursday. These winds may
persist into next weekend as upper level ridging looks to build back
across the west coast. Unfortunately, the large scale pattern looks
to favorable a continued dry pattern as this ridge settles across
the region in a rex block set-up which would deflect the Pacific
storm track away from the western U.S. Fuentes

&&

.AVIATION...

A cold front will sweep southeast across the area late tonight and
early Saturday morning and bring a few showers to mainly western NV.
Best shower coverage will extend from the Basin and Range
(KNFL/KLOL) into northeast NV with lesser coverage farther west
toward KRNO-KCXP-KTVL-KTRK. Only brief MVFR conditions are
expected with this fast moving band of showers. While significant
snow accumulations are not expected for area runways, a dusting of
snow to about a quarter of an inch is possible, especially on
exposed surfaces. For accumulations up to one inch...there is a
10% chance at KRNO/KCXP southward to about KBAN along the eastern
Sierra and about a 20% at KLOL/KNFL.

Ridge winds will stay gusty as the flow direction switches more
easterly by Saturday night. Expect mechanical turbulence over the
Sierra down into the Central Valley of California. Hohmann/Boyd

&&

.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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