Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 102210

Area Forecast Discussion
National Weather Service Reno NV
210 PM PST Wed Jan 10 2018


A fast moving shortwave on Thursday will bring breezy conditions,
especially north of Interstate 80, with light precipitation for
areas near the Oregon border. Dry conditions with slightly above
average temperatures will return for the weekend, with more active
weather for next week.



A weak, fast-moving upper wave brought some light warm air
advection precipitation to northeast California and western Nevada
this morning. Snow levels were generally above valley floors, with
the exception of brief periods of light snow around Lake Tahoe
and for locations down to 4500-5000 feet north of Susanville and
Lovelock. Precipitation has tapered off around the region this
afternoon as the wave exits into northeast Nevada and Utah.

Another piece of shortwave energy moves through the Pacific Northwest
on Thursday into Thursday night which will bring increasing winds,
especially for areas north of a Portola-Pyramid Lake-Lovelock line.
A few light showers are possible in northeast California, mainly near
the Oregon border, but the best moisture and dynamics remain north
in Oregon and Idaho.

Behind Thursday`s feature an upper level ridge builds over the West
for the end of the week and into the weekend, bringing dry conditions
with mild afternoon temperatures. All this will change next week as
the large-scale upper ridge finally gives way and opens the door
for more significant precipitation. See the long term section for
additional details. -Snyder/Dawn

.LONG TERM...Next week...

There were no major shifts in the forecast for the extended
period. Changes were limited to the attempt to fine-tune timing
of waves as we head into a more active period of weather.

Medium range models remain fairly consistent and cohesive with
the timing/intensity of quick-hitting weaker wave early/mid next
week. Snow levels remain relatively high since the wave is
projected to lift and weaken as it moves through the northern
Sierra and northern Nevada. Precipitation chances were lowered in
areas that favor shadowing, but were increased along the Sierra
crest Monday night and Tuesday. While this is a warmer storm,
some high elevation snow is probable and could impact higher
Sierra passes. Also, upper level winds are not very impressive
with this wave, but some turbulence and gusty ridge level winds
can be expected. Both EC and GFS are showing a more distinct dry
period Tuesday night into Wednesday, so precipitation chances were
trimmed behind the wave.

Beyond Wednesday...Deterministic EC and GFS begin to diverge by
Wednesday night mainly in timing of a significant low pressure
system dipping down the Pacific Coast Thursday into next weekend.
This system does display some characteristics of being supported
by an Atmospheric River. However, it is uncertain where this
feature will make landfall. Therefore, the main message continues
to be that ensembles and deterministic runs continue to favor
wetter and colder conditions for the last half of January. Boyd



Sustained winds of 30-50 kts over higher ridgetops will continue
to bring areas of turbulence downwind of the Sierra this afternoon.
Turbulence may ease some overnight into Thursday morning as the
flow aloft becomes less favorable (northwesterly) for mountain
waves. However, as the next upper wave approaches Thursday
afternoon winds will go back to southwest and west aloft for a
return to turbulent conditions through Thursday night.

As far as CIGS/VIS, any higher (above about 8 kft MSL) terrain
obscuration this afternoon should dissipate tonight between upper
disturbances. Thursday, the bulk of terrain obscuration along and
east of the Sierra crest should be north of Interstate 80, and
especially north of a KSVE-KWMC line where a few light showers
will be possible. -Snyder


.REV Watches/Warnings/Advisories...


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