Winter Weather Advisory 3, NWS Reno, NV

Area Forecast Discussion
National Weather Service Reno NV
332 AM PST Sat Jan 23 2021

.SYNOPSIS...

Light snow is working its way north to south through the region
this morning. Accumulations will generally be light with slick
conditions likely for west central Nevada. After a lull this
evening through Sunday afternoon, the next storm arrives with
more snow and slightly stronger winds through Monday. You may need
to consider leaving earlier for your Monday morning commute. The
most significant storm will impact the region the middle of next
week bringing ample moisture and potential for heavy snow
accumulation to the Sierra and potentially into western Nevada.

&&

.SHORT TERM...

The biggest changes were to add Winter Weather Advisories for the
Sierra from western Lassen County through Mono County, Sierra
Front of Nevada, and west-central Nevada Sunday evening through
Monday morning. Also, lingering snow chances were increased in
the wake of the passing system Monday afternoon and evening with
flow becoming more upslope along the Sierra south of Highway 50.

A band of snow is currently progressing through northern Nevada
and northeastern California this morning. At the time of this
writing the position is from around Susanville stretching
eastward across Pyramid Lake and Churchill/Pershing counties. This
deformation band is pivoting along eastern
Pershing/Churchill/Lander counties and will bring the most
precipitation to these areas. 1-4 inches of snow accumulation is
likely for west-central Nevada with higher amounts for Lander
County. Elsewhere, forecast amounts continue to hold for light
amounts generally a dusting up to 1 inch. Still, if you are out
this morning in the Reno Metro, considering giving yourself a
little more time to get to your destination as even a little snow
can cause issues on untreated road surfaces. Otherwise, northerly
flow will create hazardous boating conditions on Pyramid Lake; you
may want to consider delaying recreational activities until
tomorrow if possible.

The parent low will drag this band of precipitation south this
afternoon with a lull in snow for this evening through Sunday
afternoon. The next system will bring more consistent and
widespread chances for light to moderate snow accumulations.
Models continue to show a moisture flux into the region with low
pressure dropping down west of the Sierra. The resultant flow
regime and atmospheric moisture will allow for decent
accumulations of snow across the region and will likely be an
issue for Monday morning's commute; plan on delays. Low pressure
drops southward Monday evening lowering precipitation chances by
Tuesday morning.

Expected snow amounts Sunday night through Monday: 6 to 12 inches
along the higher Sierra, 3 to 6 inches in the Tahoe Basin, 1 to 4
inches along the Sierra Front and for west- central Nevada.
Localized higher totals will be possible where lake enhanced bands
form downwind of Lake Tahoe and Pyramid Lake. Biggest potential
hazard from lake banding would be along Interstate 80 in the
vicinity of Fernley Monday morning.

LONG TERM...Tuesday into next Weekend...

...Increasing Potential for a Significant Winter Storm Wed/Thu...
...Heavy snowfall likely across the Sierra and into Western Nevada...

As our weather transitions into an active pattern, eyes will be
on a significant winter storm targeting late Tuesday through at
least Thursday with potential reinforcing waves behind it into
next weekend. What will make this storm much more impactful is its
associated moderate atmospheric river moisture tap that looks to
push into the Sierra and into western Nevada. While confidence is
increasing in seeing our best snow totals of the season, likely
measured in feet in the Sierra, there is still some question on
the high end potential.

Initial timing of this storm targets Tuesday evening for the main
IVT moisture plume to begin moving across northern California with
heavy Sierra snowfall through much of the day on Wednesday. The
precursor storms ahead of this one will help set the stage for
having lower snow levels at the onset with colder air already in
place. This also includes western Nevada valleys which may see a
brief rise to near 4500 feet Wednesday afternoon with a rain/snow
mix possible but overall snow should be most prevalent through
the duration. That means significant snowfall totals (possibly
6-12" as early estimates) are increasingly possible for far
western Nevada valleys and foothills, with lesser but still
significant totals possible into portions of west-central Nevada.

Overall, the main question on exactly how big the snow totals could
be in the Sierra will center around the timing of how the trough
offshore digs which in turn determines if the the AR plume gets
drawn back across the Sierra on Thursday after its initial pass
on Wednesday. So far the GEFS/GFS is the most aggressive in
pivoting this moisture back across us while the EC camp is more
progressive. This leaves the QPF/snow estimates on Thursday-Friday
at a much lower confidence level.

Nonetheless, it would be wise to keep a very close eye on the
forecast as major impacts are expected across the Sierra beginning
late Tuesday and spilling into western Nevada through Wednesday.
This does have potential to be a long duration event with
reinforcing waves yielding off and on periods of moderate/heavy
snowfall through much of the remainder of next week. Also keep in
mind that if the storm turns out to trend towards the high-end of
predictions, travel could wind up being impossible at times in
the Sierra with areas of blizzard conditions and periodic road
closures. Fuentes

&&

.AVIATION...

A band of light snow will continue to drift south across west-
central Nevada with snow amounts of 1-4 inches for KLOL-KNFL-KHTH.
Best chances for accumulation will be through 18Z this morning. A
dusting to up to one inch is possible across KRNO-KCXP-KMEV.
Periods of LLWS will also be possible this morning.

Another storm will move into the region Sunday through Monday
bringing higher chances of 1-4 inches of snow for western Nevada
and 3-6 inches for Sierra terminals. Winds will be weaker, but
snow accumulations higher. IFR conditions will be more widespread.

Yet another and much stronger storm is expected for the middle of
next week with significant Sierra and western Nevada snow
accumulations possible. Periods of gusty winds are also possible
ahead of this system. Hoon/Fuentes

&&

.REV Watches/Warnings/Advisories...
NV...Winter Weather Advisory until 4 PM PST this afternoon NVZ001-004.

     Winter Weather Advisory from 7 PM Sunday to 4 PM PST Monday
     NVZ001-004.

     Winter Weather Advisory from 4 PM Sunday to 10 AM PST Monday
     NVZ002.

     Winter Weather Advisory from 7 PM Sunday to 10 AM PST Monday
     NVZ003.

CA...Winter Weather Advisory from 7 PM Sunday to 4 PM PST Monday
     CAZ073.

     Winter Weather Advisory from 4 PM Sunday to 4 AM PST Monday
     CAZ071.

     Winter Weather Advisory from 4 PM Sunday to 10 AM PST Monday
     CAZ072.

&&

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