Area Forecast Discussion
Issued by NWS Reno, NV

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000
FXUS65 KREV 142149
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
249 PM PDT Sat Apr 14 2018

.SYNOPSIS...

After a dry and warm Saturday, a storm will bring gusty winds to
the region Sunday with rain and snow possible late Sunday evening
through Monday. Slick road conditions will be possible Monday
morning. A weaker storm could bring light precipitation Wednesday
night through Thursday. Below average temperatures are expected
for next week.

&&

.SHORT TERM...

The Sunday through Monday storm continues to be the focus of
interest in the short term. Wind and Winter Weather Advisories have
been issued for this event.

For Sunday, winds will strengthen as thermal and pressure gradients
increase ahead of the approaching shortwave and cold front. Wind
gusts of 45-55 mph are likely early Sunday afternoon through the
evening. Stronger gusts up to 70 mph are possible along wind prone
areas of I-580, US-395 from Susanville to Mono County, and US-95
through Mineral County. The Sierra crest could see gusts above 80
mph. Breaking lee-waves will be possible which could cause
turbulent conditions for aircraft. Areas of blowing dust may be
possible Sunday afternoon, especially in west central NV including
Fallon-Lovelock-Yerington-Hawthorne. The stronger winds could
extend into the late night hours for Mono-Mineral-southern Lyon
counties.

As the shortwave and associated cold front move inland, rain and
snow will quickly develop across northeast CA by mid-late Sunday
afternoon, with the heaviest precip then pushing south into the
Tahoe basin and Alpine County by Sunday evening. A short period of
spillover rain and snow will likely spread into the Reno-Carson
vicinity Sunday evening, with most activity tapering to snow showers
after midnight. We have trended precip/snow amounts higher as the
model solutions have shown a more perpendicular positioning of
the jet to the Sierra crest which will generate better forcing and
spillover.

Total accumulations of 3-6" are possible at lake level in the Tahoe
region, with localized amounts up to a foot possible above 7000
feet, especially near the Sierra crest. For travel over the
Sierra passes on Sunday, it is strongly advised to complete the
trip during the afternoon before conditions quickly become
hazardous toward sunset and through much of the night.

For northeast CA, much of the heavier precip looks to arrive prior
to sunset, limiting snowfall accumulations. With snow levels falling
to valley floors by late Sunday night, we could potentially see a
bit of snow (generally less than 1") down to the valley floors of
far western Nevada and northeast California. Foothill areas around
Reno-Carson City including Virginia City could see a couple inches
of snowfall. Even though it is mid-April, plan for slick road
conditions around the urban areas for the early Monday AM commute,
with conditions improving by mid-morning as snow on roads will melt
more quickly due to higher springtime sun angles.

For Monday afternoon and evening, snow shower chances remain due
to unstable conditions. This could produce isolated thunder and
snow pellets/graupel especially for northeast CA and areas north
of US-50 in western NV. The main hazard to watch for will be
rapid drops in visibility when heavier showers move through Monday
afternoon and evening. -Johnston/MJD

.LONG TERM...Tuesday through Saturday...

The main forecast challenge continues to be reconciling timing
differences between the GFS and ECMWF. Therefore, changes were
fairly minimal and primarily limited to increasing QPF and
precipitation chances marginally with the in-coming midweek system.

Mid range models remain consistent with themselves with the EC
continuing to be the faster of the two solutions while GEFS
continues to edge towards the slower GFS. The result is minimal
changes and a broad-brushed approach to QPF and precipitation
chances. Both suites did marginally increase QPF in the Sierra which
is reflected in the current forecast.

The bottom line is that this system will be relatively fast-moving,
thus limiting the amount of precipitation. Still, snow levels will
be low, so expect several inches of accumulation in the higher
Sierra with lower amounts below 7000 feet. A few flurries or snow
showers cannot be ruled out for western Nevada valleys, but forcing
parameters for this system are leaning towards more of a shadowed
scenario for lee-side valleys.

Models are in relative good agreement for next weekend with low
amplitude ridging over the Great Basin and a lifting low for the
Pacific Northwest. Temperatures should warm somewhat into the low
60s for western Nevada and low 50s for Sierra valleys while winds
drops off Saturday. -Boyd

&&

.AVIATION...

The next storm will bring strong southwest winds Sunday afternoon-
evening (mainly from 18z-06z) with peak gusts to 45 kt in most
areas, except about 5-10 kt lower for the Tahoe terminals.
Widespread turbulence is likely, with pockets of LLWS.

Accumulating snow and IFR conditions are expected at the Sierra
terminals Sunday night, especially prior to midnight for KTRK-KTVL.
The chances for snow accumulation on paved areas look minimal for
western Nevada terminals, with a slightly higher chance for KRTS-
KMEV than at other terminals. -MJD/Hoon

&&

.REV Watches/Warnings/Advisories...
NV...Wind Advisory from 11 AM to 11 PM PDT Sunday NVZ003>005.

     Wind Advisory from 2 PM Sunday to 2 AM PDT Monday NVZ001.

     Lake Wind Advisory from 8 AM to 5 PM PDT Sunday for Lake Tahoe
     in NVZ002.

     Winter Weather Advisory from 5 PM Sunday to 8 AM PDT Monday
     NVZ002.

CA...Wind Advisory from 11 AM to 11 PM PDT Sunday CAZ070-071.

     Wind Advisory from 2 PM Sunday to 2 AM PDT Monday CAZ073.

     Lake Wind Advisory from 8 AM to 5 PM PDT Sunday for Lake Tahoe
     in CAZ072.

     Winter Weather Advisory from 5 PM Sunday to 8 AM PDT Monday
     CAZ072.

&&

$$

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



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