High Wind and Heavy Rain in Nevada, December 21 to 22, 2024

Area Forecast Discussion
National Weather Service Reno NV
227 AM PST Sat Dec 21 2024

.SYNOPSIS...

* Gusty strong winds are expected today in the Sierra and along
  Highway 395 and I-580, likely creating recreation and travel
  impacts.

* Periods of light rain and high elevation snow through Sunday with
  some slick roads and travel delays for Sierra passes possible.

* Monday will be the best day for holiday travel before a stronger
  storm arrives Christmas Eve.

&&

.DISCUSSION...

Our stretch of stormy weather begins today as our first storm is
ejecting across the far eastern Pacific per latest moisture-channel
imagery. This transient storm will bring light rain and high Sierra
snow later today, but of greater impact will be gusty winds across
the Sierra into far western Nevada where Wind Advisories have been
issued. Winds increase throughout this morning in response to a belt
of amplified southwesterlies aloft overspreading the region,
supporting Sierra ridgetop gusts in excess of 100 mph through the
afternoon. Lower elevation Sierra valleys, especially in and
around the Tahoe Basin, along Highway 395/I-580 and Sierra Front
communities (e.g. Reno, Sparks, Carson City, Minden) will see
strongest gusts of 40-50 mph between 9 AM and 2 PM PST when latest
CAMs advertise a potential downslope scenario. There is even a
15-30% chance that these locales will see gusts exceed 50 mph
during this timeframe. Needless to say, it'll be a windy day today
so be prepared for recreational impacts and bumpy flights into
and out of regional airports.

A band of light showers will move through the region from late-
morning through the afternoon before tapering off in the evening.
Accumulating snow of 1-4" will be confined to elevations above
7500 feet, which may yield some slick roads for Sierra passes. A
tandem of subtle trough passages will bring two waves of light
showers on Sunday with the first wave moving through Sunday
morning and second, more showery wave occurring Sunday night. Once
again, precipitation will be light on Sunday with perhaps a
dusting to 2" of snow along the Sierra crest by sunrise Monday as
snow levels remain above 8000 feet.

For those of looking for a day to travel for the holiday, Monday
will be your day to do it as upper ridging will provide a brief
intermission in the unsettled weather. Be sure to take full
advantage of this break Monday to travel because our next storm
arrives Christmas Eve. This storm will be stronger than its weekend
predecessors, bringing another round of gusty winds, valley rain,
and heavier mountain snowfall. Snowfall totals haven't changed much
from the afternoon forecast suite with the Sierra crest having a
greater than 60% chance of 6+" of snowfall by the time you're
opening gifts Christmas morning. In a "boom" scenario, there is 30-
50% chance that highest Sierra peaks end up with a foot or more of
snowfall. Similar odds (30-50%) also exist for a White Christmas (1"
or more of snow Christmas AM) for communities near lake level. Snow
levels fall to near 5500 feet in concert with waning shower activity
Tuesday night into Wednesday morning, so there could be a dusting of
snow for foothills/Virgina City during this narrow timeframe. While
these numbers will likely change in coming days, there is high
confidence that snowfall and gusty winds will induce recreation
and travel impacts on Christmas Eve.

Christmas will feature another break in between storms as dry,
perhaps a bit chilly weather prevails. Another storm appears
possible late next week with unsettled weather favored to wrap up
2024.

-Salas

&&

.AVIATION...

Periods of LLWS and turbulence are expected today as FL100 winds
increase to 50-70 kts by 18Z. The period of greatest wind impacts
continues to be favored from 16-22Z for KTRK/KTVL and KRNO/KCXP/KMEV
before surface winds begin to weaken. Mountain wave turbulence from
the Sierra crest eastward will likely persist throughout the weekend
as FL100 winds remain above 40-45 kts.

Light rain showers may result in occasional MVFR conditions and
mountain obscuration after 18Z for regional terminals before
precipitation ends in the late afternoon. Additional waves of
showers are expected Sunday.

-Salas

&&

.REV Watches/Warnings/Advisories...
NV...Wind Advisory until 4 PM PST this afternoon NVZ002-003.

CA...Wind Advisory until 4 PM PST this afternoon CAZ071-072.

&&