Area Forecast Discussion
Issued by NWS Reno, NV

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000
FXUS65 KREV 202256
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
256 PM PST Wed Feb 20 2019

.SYNOPSIS...

Heavier snow showers will shift to areas south of Highway 50 by
this evening. Road surfaces that are wet this afternoon could
freeze and produce hazardous icy conditions through tonight. Light
snow showers with heavier lake-effect snow bands are likely for
Thursday. Cold conditions will continue into this weekend, with a
possible transition to a milder and wetter pattern next week.

&&

.SHORT TERM...

Bands of snow have been moving across the Tahoe basin and far
western NV, although accumulations have been minimal with sunshine
filtering through. The heaviest snow in the advisory areas and
wettest roads (and greater risk of re-freezing after sunset) so
far has moved across Carson City and Douglas County, and will
shift into southern Lyon/Mineral counties thru early evening.
Other parts of the Reno-Sparks vicinity could still experience
some patchy ice this evening but chances for a widespread freezing
of roads are lower.

Most of the snow should diminish later tonight except for a few
lake-effect snow showers possible south of Pyramid Lake and
southwest of Tahoe. However, by early Thursday morning some wrap
around moisture combined with a moist upslope flow could bring
areas of light snow back to the Reno-Carson-Minden region.
Accumulations should be minimal (generally less than a half inch)
but it could still produce some slick conditions for the morning
commute. This flow continues through much of the day, so periods
of light snow could persist from Reno-Tahoe southward to Mineral-
Lyon-Mono counties. Overall snow amounts are likely to remain
below advisory thresholds, but some enhanced snow amounts are
still likely south-southwest of Tahoe/Pyramid/Walker lakes (with
2-6" or more in isolated locations), and the evening commute could
also be impacted by icy roads if all day light snow prevents some
drying. We are expecting a brisk north wind of 10-20 mph with
gusts 25-30 mph, especially over northwest and west central NV, so
if there are sufficient breaks in snow there should be a chance
for roads to dry out.

By Thursday night, the wrap around moisture is expected to
diminish with lake-effect snow bands also winding down. Light
upslope snow showers remain possible mainly south of US-50 and
into parts of Alpine, Mono and southwest Mineral counties, with
minimal additional accumulations. Very cold temperatures are
expected with lows mainly in the single digits and teens, with
sub-zero lows for colder Sierra valleys.

For Friday-Saturday, mainly dry conditions are expected except for
some light snow possibly returning to areas north of Susanville-
Gerlach as another low pressure drops south along the coast near
the US-Canada border. This low will begin to tap moisture mainly
directed toward the Pacific Northwest, but then move slowly south
by Saturday night. How far south this moisture gets will become
a big factor in precip potential later in the weekend and into
next week, with a variety of potential scenarios as mentioned in
the long term section below. MJD

.LONG TERM...Sunday through Friday...

Main changes were to increase chances for precipitation across the
region since operational simulations agree that it will be fairly
wet Sunday through Tuesday. Snow and rain amounts were also
increased to reflect the wetter pattern that may set up.

The pattern remains quite active for much of next week as the
eastern Pacific ridge amplifies and allows systems to sneak beneath
it (undercut the ridge) into the West coast.

Something to keep in mind with the forecast: the story can change
from day to day with model fluctuations and changes with the current
weather pattern. While some simulations hint at some very strong
storms for next week, others do not, so we are here to keep you
informed as best as we can with the data that is available to us.
What can you do? Check the forecast discussion OFTEN! New model
simulations can lead to changes in the forecast, and if you have
travel plans then you should keep yourself as informed as possible.

Simulations are still showing the potential for a large, cold trough
to slowly migrate southward from the Pacific Northwest into northern
CA and NV Sunday-Tuesday. Some simulations show this trough
combining with sub-tropical moisture by Tuesday, which would result
in a lot of precipitation (rain and snow) for northern CA and NV.
Uncertainty is high for this scenario, especially since the ensemble
mean isn`t really on board with that idea at the moment.

By Wednesday and Thursday, the moisture along with the dynamics
shift northward into OR/WA with warmer temperatures and lower
precipitation chances for the Sierra and western NV.

Friday onward - the simulations continue to hint at an active
pattern with potential for wetter and windier conditions for early
March. Since the details are FAR TOO EARLY to dig out, we
recommend keeping an eye out for updates. -Edan

&&

.AVIATION...

Periods of snow will continue through late afternoon and early
evening at the main terminals, producing IFR conditions at times
mainly prior to 01Z, although the Sierra terminals may see more
-SHSN with periods of IFR further into this evening.

For Thursday, periods of -SHSN could continue or redevelop at all
of the main terminals. The main effect will likely be mountain
obscurations, although periods of MVFR or IFR remain possible
especially for the Sierra terminals. Also, some lake enhanced snow
bands could bring cigs/vsby down lower if they pass over a
terminal (more likely over KTVL/KRNO). Brisk north winds with
gusts to 20 kt are likely through much of Thursday.

The snow showers are projected to diminish Thursday night, then
dry and cool conditions with light winds are expected Friday. MJD

&&

.REV Watches/Warnings/Advisories...
NV...Winter Weather Advisory until 3 AM PST Thursday NVZ001.

     Winter Weather Advisory until 7 PM PST this evening NVZ003.

CA...None.
&&

$$

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


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