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000
FXUS65 KREV 290954
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
254 AM PDT Wed Mar 29 2023

.SYNOPSIS...

While the main snow area associated with a late winter storm has
departed, bands of snow showers will redevelop this afternoon and
continue through tonight, with additional spotty accumulations.
Isolated shower chances continue with a slow warmup Thursday
through Saturday, then another colder storm brings increased
snow shower chances late Sunday into early next week.

&&

.DISCUSSION...

Area web cameras continue to show snow-covered roads across the
Sierra and Tahoe region, with the main snow band retreating to
Mono County. An area of snow also continues over west central NV.
These snow areas are expected to slowly wind down and end by
daybreak--with the Winter Storm Warning remaining in effect for
the Sierra until expiration at 5 AM. Few snowfall reports are in
at this time, although the Mammoth Mountain snow study plot near
the main lodge reported about 25" new snow between 2 PM and 2 AM
with accumulation rates generally 2" to 2.5"/hour. Peak wind gusts
were mainly in the 50-60 mph range across western NV Tuesday,
except Hawthorne airport received enhanced gusts up to 76 mph
between 4-6 PM, along with several reports of blowing dust across
the Basin and Range.

After the current activity diminishes, we`ll see a short break in
activity through the mid-late morning, before scattered snow
shower bands form and move across the Sierra this afternoon.
Additional snow amounts will generally be 1-3" in most areas,
with only spotty accumulations in heavier bands during the daytime
hours.

For this evening, scattered snow shower bands will slowly
decrease with another couple inches possible for the Sierra, but
a few of the high resolution guidance scenarios leave open the
possibility of a longer lasting snow band affecting a few parts
of western NV. The small-scale low and upper level features along
with the terrain-driven forcing don`t appear to line up in the
same favorable places when compared to last Saturday night`s snow
band event, and the low level wind trajectories don`t support
lake-effect contributions from Tahoe into far western NV. However,
we can`t entirely rule out about a 10-20% possibility that
isolated portions of far western NV from Reno-Fernley southward
across Douglas-Lyon-western Mineral counties could receive 2 or
more inches of new snow tonight. If this snow occurs, slick and
icy conditions would produce Thursday AM commute impacts
especially prior to sunrise. We`ll update the Special Weather
Statement as a heads-up for this lower probability but higher
impact scenario.

Thursday and Friday look quieter overall, although weak
orographic lift near the Sierra crest and a brush-by shortwave
near the Oregon border may bring very light snow showers to these
areas Thursday afternoon. Friday is the best bet for all areas
being dry with temperatures a little milder, rising into the
lower-mid 50s for lower elevations and edging above 40 degrees for
Sierra communities.

For the upcoming weekend, the ensemble guidance continues to be
consistent with a broader trough and Pacific jet stream edging
southward across the Pacific Northwest and far northern CA
Saturday-Saturday night, with the southern edge of the moisture
feed bringing light snow chances back across northeast CA from
Tahoe northward, and far northwest NV. Accumulations will be
limited due to most precip occurring during the daytime, but up to
a couple inches could fall near the Sierra crest and in the
Surprise Valley at the onset early Saturday morning or as activity
winds down in the evening. Elsewhere, dry conditions are expected
with some increase in winds Saturday afternoon, including stronger
Sierra ridge gusts.

The next storm system within this moist Pacific flow is projected
to drop in from the north Sunday evening into Monday, bringing a
reinforcing shot of cold air, gusty winds and increased snow
shower chances across a majority of eastern CA-western NV.
Currently the moisture trajectories are more over land compared to
yesterday`s storm, but frontal forcing again brings the potential
for slick and icy travel conditions even in lower elevations for
the Monday AM commute, with very chilly temperatures about 15-20
degrees below average during the day Monday. The unsettled weather
pattern with below average temperatures likely continues into the
Easter weekend, with maybe a brief warm-up after Monday but
another colder storm possible by the end of next week. MJD

&&

.AVIATION...

* Winds have decreased from their earlier peak across the region,
  but remain elevated aloft. SW FL100 winds are currently
  sustained around 45 kts with mountain wave turbulence along and
  downwind of the Sierra likely to continue. While some surface
  gusts up to 20 kts remain possible south of US-50 today, most
  terminal sites will see lighter winds.

* Main precipitation band as of the time of writing has a SSW-NNE
  orientation from Mono Co extending to near and east of US-95.
  Anticipate IFR conditions within this band along with terrain
  obscuration. This band will continue shifting toward the east
  and southeast into the morning hours.

* Snow/pellet showers will develop today, most prevalent for
  Sierra terminals with an additional 1-5" of accumulation
  possible through tonight. There`s also a 15% chance for a stray
  thunderstorm to reach the Sierra crest this afternoon, but
  better chances to the west. Showers will be more hit or miss
  into western NV today, but brief lowering of ceilings and
  visibility along with terrain obscuration should be expected.
  There is a 25% chance for up to 1" of snow at any given airport
  location in western NV during the day, but any runway
  accumulation will be limited and short-lived.

* One scenario to watch for is banded snowfall after sunset
  tonight, which is showing up in some high resolution models.
  The problem is the exact location of this banding continues to
  move around by 20-50 miles. The greatest overlap per Dynamic
  Ensemble-based Scenarios is a band from Fernley arcing toward
  the Virginia Range and into the Greater Reno Metro area; with a
  secondary area for western Mineral and Southern-central Lyon
  Counties. If this banding does occur, KRNO could see 1-2" of
  snow accumulation on runways tonight.

* Much improved flying conditions return for Thursday. -Dawn

&&

.AVALANCHE...

* The main snow band has ended north of Ebbetts Pass and will
  diminish prior to daybreak south of Ebbetts Pass through Mono
  County, with less than 3" of added low-density snow (snow-liquid
  ratios 18:1 to 20:1) on top of the heavier snow that fell since
  late Tuesday morning.

* Scattered snow showers with snow-liquid ratios around 16:1
  return this afternoon and evening, producing hit or miss amounts
  less than 5" with SWE less than 0.25". MJD

&&

.REV Watches/Warnings/Advisories...
NV...Winter Storm Warning until 5 AM PDT early this morning NVZ002.

     Wind Advisory until 2 AM PDT early this morning NVZ001.

CA...Winter Storm Warning until 5 AM PDT early this morning CAZ072.

     Winter Storm Warning until 5 AM PDT early this morning CAZ073.

&&

$$