Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 180957
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
257 AM PDT Tue Apr 18 2017

.SYNOPSIS...

Rain and high elevation snowfall will continue this morning with a
weak surface front drop south through Mono and Mineral counties this
afternoon. Showers will diminish this evening with a brief break in
the weather Wednesday afternoon. After a final weak system Wednesday
night and Thursday, a drier trend with a significant warm up is
expected heading into the weekend.

&&

.SHORT TERM...

An upper low off the West Coast is currently driving a plume of
subtropical moisture across the the Sierra which is also easily
spilling over into western Nevada. Snow level profiler data on the
west slopes of the Sierra currently peg the snow levels between
about the 7,500-8,000` range so far this morning. A weak frontal
boundary will also move through this morning and will provide a slow
lowering of snow levels to near 7,000`. This will provide a small
window where some slush could accumulate on higher passes, however
it should melt off quickly by mid-morning.

Banded precipitation with the front will yield periods of moderate
rainfall this morning through about 8am across the I-80 corridor
before becoming scattered as the front pushes south into Mono and
Mineral counties. Instability will be present today but forcing
could be the limiting factor for scattered thunderstorm development
this afternoon as jet forcing and low-level frontal forcing remain
too far south. Still, won`t rule out an isolated lightning strike or
two, with pellet showers and small hail possible in heavier
convective cells. Showers quickly diminish this evening as the sub-
tropical moisture source moves south and instability decreases after
sunset.

We dry out briefly and maintain breezy conditions on Wednesday ahead
of the next disturbance which will move through tomorrow evening
into Thursday morning. This system will be a colder and quick moving
shortwave trough with the best potential for a short period of
precipitation from the late night through early morning hours. Snow
levels will drop near 5,500-6,000 across the northern Sierra and far
western Nevada by Thursday morning, but moisture is limited.

Precipitation amounts look to be in the 0.20-0.40" range along the
northern Sierra and far northeast California with only a few
hundredths south into Mono County. Snowfall associated with this
system will generally be light, mainly 1-3" around Tahoe-Truckee and
northeast CA above 5000-5500 feet. Some slick/slushy travel
conditions are possible into Thursday morning around Tahoe (mainly
near or above 6500 feet) and higher elevation roads in northeast CA
(Fredonyer/Yuba passes and CA-44 west of Susanville).  Fuentes


.LONG TERM...Friday and beyond...

Upper level ridge of high pressure will build across the region
Friday with models a bit more progressive in shifting this ridge
east on Saturday. Temperatures will warm to above normal levels but
increasing winds aloft and tightening gradients will bring gusty
afternoon and evening winds Saturday. High temperatures will rise
into the 60s Sierra valleys and 70s across lower elevations of
western NV on Saturday.

The trough will move across the region Saturday night and bring a
slightly cooler airmass for Sunday. We cooled temperatures a few
degrees Sunday although it is still going to be above normal. This
pattern of inland trough passages is going to continue next week
with our area staying just on the south side of the jet axis. This
will result in periodic trough passages with the one Monday night
and Tuesday a bit farther south than the weekend trough. Monday will
be another warm day with afternoon breezes followed by cooling
temperatures and a low chance of showers Monday night and Tuesday.
Dynamics along front may bring wetting rains to areas north of
Susanville-Gerlach Monday night-Tuesday morning. Another trough in
northwest flow may affect the area later in the week. Hohmann

&&

.AVIATION...

For today, a stronger and wetter shortwave will enhance
precipitation with a continuous period of terrain obscurement along
the eastern Sierra and widespread MVFR conditions for KTRK/KTVL,
eventually spreading south to KMMH. Snow levels will remain above
Sierra terminals so snow accumulations are unlikely. Western NV
airports will see periods of light to occasionally moderate rain
with showers, but conditions should remain mostly VFR with higher
mountain tops possibly becoming obscured.

For this afternoon, there is a low (10%) chance for thunderstorms
over west-central Nevada (well east of KRNO) although morning model
data suggests upper jet/forcing may shift too far south by afternoon
with a post frontal environment less conducive for a lightning
threat. If any storms form, small hail (less than 1/2") and a few
lightning strikes will be possible.

Surface winds will be fairly modest today (gusts 20-25 kts) but
Sierra ridges will continue to have gusts 50-60 kts. Some light
turbulence will remain possible. Hohmann/Snyder

&&


.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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