FXUS65 KREV 182230
Area Forecast Discussion
National Weather Service Reno NV
230 PM PST Mon Feb 18 2019
A few leftover snow showers south of Pyramid and Walker Lake will
diminish this evening, with dry and cool conditions prevailing
through Tuesday night. Another cold low pressure will bring more
snow and snow showers Wednesday through Wednesday night, with lake
effect snow bands again possible Thursday. Cold conditions will
continue with another chance of snow showers for next weekend.
.SHORT TERM...through Wednesday night...
Only notable change in the short term was speeding up the arrival
of snow during the day on Wednesday from US-50 northward, as
indicated by the latest guidance trends.
Lingering flurries or brief snow showers were still showing up
into this evening south of Pyramid and Walker Lakes on the high-
resolution guidance, but by this time the instability will be
decreasing, resulting in little to no additional accumulation.
Otherwise, it will be quite cold for the next couple of nights with
the widespread snow cover and light winds. Tonight looks like the
colder night (lows mainly in the single digits and teens, with
sub-zero values in typically cold Sierra valleys) as overall cloud
cover decreases, while some increase in cloud cover Tuesday night
ahead of the next weather system limits the radiational cooling
effects. Temperatures will not rebound much Tuesday (highs mainly
in the 30s) as light northerly flow persists.
By Wednesday, the next upper low is forecast to drop southward
toward the Sierra and western NV. Most model scenarios are
maintaining persistence on this track which would be more typical
of a slider style system, although with the slightly faster
timing, snow would begin north of Susanville-Lovelock during the
morning, then reach the I-80/US-50 corridors by the afternoon.
Then the best snow chances push south of Reno-Truckee during the
early evening. This may affect the snowfall amounts as lower
elevation areas receiving their peak snow in the afternoon could
see less accumulation, but overall snowfall amounts up to 3"
remain likely, with slightly higher totals possible for parts of
eastern CA. This would impact the Wednesday afternoon/evening
commute across much of the area. Snow shower activity could
briefly decrease Wednesday night, then low level wind and
instability profiles become more favorable for snow showers and
lake-effect snow bands on Thursday. MJD
.LONG TERM...Thursday into next week...
Behind the departing slider system, another cold and unstable
air mass will settle across western Nevada and the Sierra. This
will produce scattered snow shower activity for areas mainly
south of I-80 and most numerous in the eastern upslope areas of
the eastern Sierra. The environment will be favorable once again
for lake effect snow showers to develop downstream to the south of
Tahoe, Pyramid, and Walker lakes.
Snow showers wane Thursday night outside of some possible
reinvigoration of lake enhanced snow showers. Most activity will
dissipate by Friday morning and we will see another short break in
the weather, but conditions will remain cold with temperatures
about 10-20 degrees below average.
The next potential for snowfall is looking to arrive sometime in
the Sunday to Monday timeframe as guidance builds another mostly
inland trough across the Pacific Northwest. Ensemble runs are
leaning towards a colder system with the EC showing higher than
average predictability in the colder outcome as well. Main
difference at this point is how cold and how far south the trough
digs. Currently the GFS favors another slider across the area
while the EC is drier. Do think we will see some snow out of this
system but probably won't get a good sense on amounts until later
in the week, which is par for the course when it comes to
VFR conditions area expected all areas tonight-Tuesday night,
although some mtn obscurations are possible tonight with some
leftover low clouds lingering near the main terminals. FZFG
potential at KTRK looks limited to less than 20% probability due
to NE-E ridge winds, limited melt-freeze cycle, and drying air
mass tonight, and increasing cloud cover Tuesday night.
The next weather system for Wednesday is a slider with -SHSN
producing areas of MVFR and IFR CIGS/VIS primarily from 18Z-03Z
for KRNO- KCXP-KTRK-KTVL, and a few hours later at KMMH, with
activity becoming more scattered thereafter. MJD
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