Winter Weather Advisory 16, NWS Reno, NV

Area Forecast Discussion
National Weather Service Reno NV
257 PM PDT Wed May 19 2021

.SYNOPSIS...

A late spring storm will bring lower valley rain and snow showers
with snow showers in the Sierra tonight into the weekend. Temperatures
turn much colder with the potential for sub-freezing temperatures
Friday and Saturday mornings in rural and suburban lower valleys.
Temperatures warm to more typical values next week. After a brief
break in weather early next week more active weather is possible.

&&

.SHORT TERM...

A well-defined cold front extends across extreme northern California
and Nevada this afternoon. Unusually cold (but not unheard of) low
pressure near the Pacific Northwest coast will invade the region
tonight and Thursday which will give the front a shove southward,
clearing Mono and Mineral counties by Thursday afternoon and early
evening.

Ahead of the cold front this afternoon, widespread southwest to west
gusts of 25-40 mph with localized gusts to 45-50 mph (western NV
Sierra Front) have developed as the pressure gradient tightens
ahead of the front. Winds have kicked off some blowing dust east
of Hwy 95/I-80 across northern Churchill and southern Pershing
counties per satellite imagery. Winds turn northerly behind the
front tonight and Thursday with breezy, brisk conditions with gusts
20-35 mph.

* SNOW: Snow levels fall to near (at front) to well below 5000 ft
  (a bit behind front) late tonight and Thursday morning. In
  general, up to an inch of snow will be possible below 5000 feet
  from Portola and Gerlach northward, with 1 to 3 inches above
  5000 feet which could create slick road conditions along
  CA-44/36 and Highway 395 north of Susanville. Farther south
  (I-80 corridor southward) the frontal timing looks late enough
  Thursday morning to limit snowfall potential for tomorrow. One
  exception could be in the higher elevations of the Sierra from
  Tahoe north where some simulations bring a burst of snow
  Thursday afternoon which could impact the Carson Range and the
  I-80 corridor over Donner Summit. As it will take a heavy burst
  of snow for accumulations this late in spring there is much
  uncertainty; however, if you are traveling over the Sierra north
  of Hwy 50 tomorrow it would be wise to check conditions before
  traveling.

  Thursday night through Friday night, cold low pressure remains
  over the region for scattered to occasionally numerous snow and
  rain/snow (lower valleys) showers. If snow showers are
  persistent and fall overnight or before 8 AM, they could impact
  travel with slick roads; the exception is in the high Sierra
  here accumulations remain possible at any time for possible
  impacts for higher trans-Sierra passes.

* SHOWERS/THUNDERSTORMS: Periods of showers start late tonight and
  continue through at least Saturday evening. Best chances of
  showers and thunderstorms will be each afternoon. Lower valleys
  that develop rain showers initially could see a quick switch
  over to snow pellet showers given the at least weakly unstable
  airmass along with low snow levels. If pellet showers remain
  persistent over any one spot, brief slick conditions are
  possible.

* COLD: Much colder temperatures will occur Thursday through
  Saturday with sub freezing lows possible Friday (most likely)
  and Saturday (lesser chances) mornings for rural and suburban
  lower valleys with hard freezes for Sierra valleys. Highs will
  be unseasonably cold with upper 40s to mid 50s for lower valleys
  Thursday and Friday with upper 30s to upper 40s for Sierra
  valleys. Slight warming is expected Saturday with more
  substantial warming Sunday and Monday.

-Snyder/Hohmann

.LONG TERM...next week...

Next week, there are signs that it may not warm up quite as fast
as previously thought as another shortwave trough moves through
the region around the Tuesday-Wednesday time frame. Temperatures
will likely stay closer to average with 60s Sierra valleys and 70s
lower valleys. The forecast is currently dry based on the national
blend of models, but isolated showers and even a few thunderstorms
cannot be completely ruled out. -Snyder/Hohmann

&&

.AVIATION...

Gusty SW-W winds in place with most terminals seeing gusts 30-35 kts
through this evening. Brief periods up to 40 kts are possible.
Mountain wave turbulence and wind shear are expected through the
evening and overnight. Winds will turn NW-N behind the cold front on
Thursday, remaining rather breezy (gusts 20-30 kts) for western
and central Nevada.

The cold front will bring a burst of snow showers tonight near the
Oregon border, translating south through northern Nevada during the
day. There is a 60% chance for snow showers and/or snow pellets by
mid-late morning for KTRK, KRNO, KCXP, KTVL, and KMEV. Anticipate
mountain obscuration along with lowering ceilings and visibility
with potential for periods of MVFR-IFR conditions. There is a 25%
chance for light snow accumulation (<1/2") early Thursday and Friday
mornings at KTRK and KTVL, and Friday morning for KMMH.

Rain, snow and pellet showers are possible for all elevations
Thursday, Friday, and Saturday afternoons as well as thunderstorms.
Terrain obscuration along with reduced CIGS/VIS should be expected,
but coverage will be scattered. -Dawn

&&

.REV Watches/Warnings/Advisories...
NV...Freeze Watch from late Thursday night through Friday morning
     NVZ001-003>005.

     Lake Wind Advisory until 9 PM PDT this evening for Pyramid Lake
     in NVZ004.

     Winter Weather Advisory from 11 PM this evening to 11 AM PDT
     Thursday NVZ005.

     Lake Wind Advisory until 9 PM PDT this evening for Lake Tahoe in
     NVZ002.

CA...Freeze Watch from late Thursday night through Friday morning
     CAZ070-071.

     Winter Weather Advisory from 11 PM this evening to 11 AM PDT
     Thursday CAZ070-071.

     Lake Wind Advisory until 9 PM PDT this evening for Lake Tahoe in
     CAZ072.

&&

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