Area Forecast Discussion
Issued by NWS Reno, NV
FXUS65 KREV 232323
Area Forecast Discussion
National Weather Service Reno NV
323 PM PST Thu Feb 23 2017
Any snow showers will dissipate tonight as high pressure briefly
builds over northeast California and western Nevada. Two
disturbances will move over the region, one late Friday night and
Saturday with a second Sunday into Monday. A light snowfall is
possible with both, although the second looks a bit stronger.
Temperatures will remain below average through early next week.
Not too much change to the forecast through Saturday night with
below average temperatures as a trough/cyclonic flow remains over
the region. After isolated to scattered snow showers dissipate
this evening with loss of daytime heating there will be a lull in
precipitation through most of Friday, although a few light snow
showers will be possible over far northeast CA and northwest NV
tomorrow afternoon and evening. Tonight is expected to be the
coldest night of the next few nights for most areas, with below
zero to mid-single digit temperatures for typically colder valleys
of northeast California and the Sierra.
The next disturbance (currently over British Columbia) will move
into the area late Friday night through Saturday. Despite the
wave`s track out over the far eastern Pacific, most simulations
remain on the dry side as the wave splits and leaves eastern CA
and western NV between the best forcing areas (Rockies and
California coast). However, with a few simulations slowing and
backing the low farther off the coast, there remains a 10-20%
chance that more moisture than expected gets injected into the
system as subtropical moisture tries to merge into the low. With
many models consistently showing the weaker and drier solution,
have sided with that for this forecast. With this in mind, I have
kept POP/QPF fairly modest as it is still possible that areas
east of the Sierra could just see clouds with no precipitation.
Saturday night, the trough axis passes to the south for decreasing
precipitation chances...although this will be short-lived as the
next system drops down the Pacific coast late in the weekend.
.LONG TERM...Sunday through Thursday...
Model simulations continue to trend eastward with the wave moving
through Sunday into Monday. This trend doesn`t allow the system
the necessary residence time over the Pacific to pickup up much
moisture. It also pushes the incoming atmospheric river south of
the Sierra altogether.
The slider nature of this pattern, and the fact there is still a
cut-off lower pressure in the eastern Pacific that could interact
with the wave, still leads to lower confidence forecast for Sunday.
The current model simulations have backed off on QPF dramatically,
but the wave is currently forecast to just brush NE California
and far western Nevada. If wave digs in slightly more it could
have a chance to pick up more moisture and push a more dynamic
front through the region.
Showers could last into Monday before a drier pattern starts to
take hold for the rest of the week. A flattened high pressure
begins to build off the coast California next week which will let
warmer air to return aloft. This, along with snow cover in some
lower valleys will allow inversions to form. -Zach
Convective snow showers will continue around the area this
afternoon. Conditions could fluctuate between VFR and MVFR with
visibility reductions to < 3SM at times. This will cause terrain
obscuration but any runway accumulations would be less then 0.5",
or even no accumulation with just wet pavement. Showers should
become less numerous this evening and dissipate overnight.
If enough upper level clearing occurs tonight KTRK could see some
fog for a few hours. A break in the weather is expected Friday
before another storm impacts the region on Saturday. -Zach
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