Forecast Discussions mentioning any of
"ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 12/27/20
Area Forecast Discussion
National Weather Service Reno NV
232 PM PST Sat Dec 26 2020
A colder winter system will produce a chance for snow Sunday night
through Monday mainly south of Highway 50. Additional fast moving
storm systems may produce additional chances for snow and gusty
winds for the upcoming week, with typical cool temperatures
expected into the start of 2021.
Bands of snow showers have lingered through parts of eastern CA
and northwest NV, producing short periods of reduced visibility
and snow or slush on portions of I-80 near Donner Summit. These
showers are likely to wind down by sunset.
After a quiet and cloudy day on Sunday with a favorable window for
travel to end the holiday weekend, attention then turns to a
closed low pressure system projected to reach the central CA
coasts late Sunday into Monday. The wobbly track of this low
continues to present varied scenarios which could range from a
widespread swath of light to locally moderate snow accumulations,
to a more spotty outcome with the majority of the snow splitting
off into two areas: west of the Sierra crest and/or into central
NV. Putting these pieces together, our most likely outcome
currently suggests the best chance for accumulating snowfall would
be in western NV and eastern CA south of US-50, with spotty
lighter amounts extending northward to near I-80. Please see our
latest Special Weather Statement for our current projected
snowfall totals Sunday night-Monday.
While this doesn`t appear to be a heavy snowfall event, the cold
temperatures could present travel concerns into Monday evening
especially across parts of Mineral, Lyon and eastern Churchill
counties where snowfall during the daytime Monday lands wet on
roads, but then freezes around/after sunset as temperatures drop
quickly into the 20s before paved surfaces have a chance to dry
out. Once again, the track and timing of the storm would determine
whether this hazard will exist, or if the worse conditions shift
more quickly into central NV.
Otherwise, daytime temperatures will remain below average with
overall light winds due to the widespread cloud cover for the
next two days and the aforementioned snow potential on Monday.
These same clouds will limit cooling Sunday night, then on Monday
night as this storm departs, most areas will be notably colder
with lows mainly in the single digits and teens, and near/below
zero for typically cold valleys. MJD
.LONG TERM...Tuesday through Saturday...
Some minor adjustments were made to the previous forecast
primarily concerning delaying the onset of the next wave by about
6 hours more into Wednesday evening rather than earlier Wednesday.
Also, ridge winds were trended higher as a 50-60kt core of winds
at 700mb progresses through the region Wednesday night into
Thursday. No major implications from these changes with the
exception that aircraft turbulence is more likely Wednesday night
Otherwise, the forecast remains on track with a couple of waves
for mid week and possibly late next weekend. The mid week wave is
shaping up more of a nuisance event with light snow accumulations
for the Sierra with a dusting possible for western Nevada. System
trajectory favors shadowing, but upper level support is on the
weaker end of the scale. Still, conditions could get breezy for
Wednesday night and Thursday with valley gusts 20-35 mph.
Temperatures will not be overly cold Thursday morning, but winds
will make conditions feel brisk.
After high pressure builds Thursday night into Friday, another
system will begin to approach for the weekend. Models delayed this
system by around 6 hours as well from previous runs, so just some
slightly chances of snow showers will be edging down the Sierra by
Saturday. Model spread continues to be wider with GFS/GEFS favoring
a split wave with EC/EC ensemble being more consolidated. NBM splits
the difference with middling chances. So, forecaster certainty for
next weekend remains on the lower end as probabilities become less
Conditions largely improve tonight over last night and this
morning; just some freezing fog potential at TRK for this cycle.
However, expect some lingering mountain obscurations that could
continue through Sunday morning.
Another wave will bring accumulating snow to mountain terminals
Sunday night into Monday morning with a dusting to around an inch
or so for western Nevada valleys along the Sierra Front. Best
chances for around an inch of snow accumulation remain south of
Highway 50 for western Nevada. Winds will not be very strong by
regional standards for this round, but expect MVFR/IFR conditions
and mountain obscurations through Monday morning. Boyd
For more information from the National Weather Service visit...