Olympic Valley, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

626
FXUS65 KREV 222229
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
229 PM PST Mon Dec 22 2025

.KEY MESSAGES...

* Heavy rains that could lead to localized flooding, and heavy
  wet snow in the Sierra above 7500 feet continues into the late
  evening.

* A brief lull in precipitation appears on Tuesday with gusty
  ridge winds.

* Another round of stormy conditions could bring significant rain
  and snow along with enhanced winds late Tuesday through
  Christmas Day into Saturday.

&&

.DISCUSSION...

This afternoon`s radar imagery depicts the bulk of the precipitation
is falling along I-80, with snow sticking to the roads. The Tahoe
Basin is seeing some lake level flakes mixing into the rain
showers. Area cameras show initial snowfall sticking to elevated
surfaces, but will eventually accumulate on the roadways there as
well. So, this highlights the biggest change in the forecast from
the previous shift, which would be the snow levels. Modeling still
tries to keep the snow levels around 8000 feet. However, the
above evidence suggests the actual snow levels around 7000-7500
feet. We anticipate a slight adjustment this afternoon with some
warming that could pop the snow levels above the 7500 foot mark
for a couple hours. However, heavy snow would work to keep the wet
bulb temperatures lowered, which could keep the precipitation
type as snow rather than a rain snow mix at lake level. As this
plume of moisture migrates northward through the day, we expect to
see the precipitation wrapped up for Mono County this afternoon.
Getting a glance at the infrared satellite image from GOES-18,
there is a break in the clouds and precipitation making it`s way
onshore near central California. This should be the break we are
advertising for Tuesday, getting in line to be our next weather
feature.

The trough that has taken residence along the Pacific coast appears
to continue to dig southward as it advances eastward, dropping the
parent low further south. This will bring colder air along with it,
which will take awhile to settle in over the region. We will start
to feel the influence from this late Tuesday evening, as showers
progress from northeastern California into western Nevada. Snow
levels are currently forecasted to hover near 7000 to 7500 feet late
Tuesday, but may fluctuate based on southerly flow working to keep
warmer air around the region. Speaking of winds, ridges will be
gusting around 60-70 mph early Tuesday, and by afternoon the valleys
could see gusts to 25-30 mph along the Sierra Front. These wind
speeds will only increase as the storm draws nearer, and by early
Wednesday the ridges could see gusts to 100 mph. Wednesday will be
marked by mountain snow, valley rain and gusty winds. For Thursday,
travel may become difficult to impossible across the Sierra, as feet
of snow are the gift that will keep on giving into the spring. We
may even see snow to western Nevada valley floors, providing
ample opportunity to get out and play in freshly fallen snow. As
of this writing the NBM guidance shows a 5% chance for 1" of snow
at sunset on Thursday at the Reno-Tahoe international Airport and
then a 35% chance for 1" of snow by sunset on Friday. These totals
will entirely depend upon snow levels and the timing of the
lowering of the snow levels coupled with precipitation timing.

This clears up late Saturday as the front drifts eastward and out
toward the Great Basin. As of now, Sunday and Monday into the new
week look dry, with breezy ridges and near-average temperatures.
HRICH

For details about the Winter Storm Watch or Winter Storm Warning,
please visit www.weather.gov/rev/winter

If you`re planning on going out to the back country in the
eastern Sierra, please visit www.weather.gov/rev/Avalanche

&&

.AVIATION...

* Band of light-moderate precipitation will continue lifting
  northward through this evening, producing MVFR-IFR conditions in
  rain and mist. By 0z most of this precip will be well north of
  I-80.

* Flow aloft remains robust with 700mb winds close to 40 knots into
  Tuesday. That will keep wind shear and some mountain wave activity
  in the TAFs. Once airmass mixes out Tuesday, gusty S/SW winds are
  likely to surface with 20-25 knot gusts likely in the afternoon.
  Otherwise Tuesday looks mainly dry with VFR conditions.

* Next storm moves in Tuesday night and Wednesday with widespread
  MVFR-IFR conditions in rain and snow, along with periods of strong
  S/SW winds and wind shear. Switchover to snow at TVL/MMH Wednesday
  afternoon per NBM p-type probabilities, with more Wednesday
  evening at TRK.

-Chris

&&

.HYDROLOGY...

Rivers and streams are running high from Alpine County north through
Lassen County. Additional rises are possible today with any periods
of moderate to heavy rain this afternoon and evening. High flows
will continue to move into lower reaches of main-stem rivers.

Flooding concerns will be renewed late Tuesday through Wednesday
when the next storm brings additional rain before eventually
transitioning to snow. Areas of concern will be urban and poor
drainage areas, and creeks and streams from Lake Tahoe through
Lassen County. The greatest flooding concern is for rivers and
streams draining large watersheds below about 6,500`. This includes
many streams in Sierra, Plumas and Lassen counties and the Susan
River.

Minor flooding is currently forecast for the Susan River on
Christmas Eve, but greater than expected rainfall and/or delayed
transition to snowfall could easily push the Susan River higher.
No other main-stem rivers are forecast to flood, but very slow
rises and high flows are expected on the Pit River near Canby,
and Middle Fork of the Feather near Portola.

Enhanced runoff and sediment transport including rock fall are
possible within and below recent burn areas, including, but not
limited to the Davis and Bear burn areas. Post-Fire debris flows are
not expected.

The River Forecast Center will be extending hours this week and
issuing additional forecasts for rivers where flooding is
expected. Check for updated river forecasts at: www.cnrfc.noaa.gov

-Tim

&&

.REV Watches/Warnings/Advisories...
NV...Flood Watch until 4 PM PST this afternoon NVZ002.

     Winter Storm Warning from 10 PM Tuesday to 10 AM PST Friday
     NVZ002.

     Winter Weather Advisory until 4 PM PST this afternoon NVZ002.

CA...Flood Watch until 4 PM PST this afternoon CAZ071-072.

     Winter Storm Warning from 10 PM Tuesday to 10 AM PST Friday
     CAZ071>073.

     Winter Weather Advisory until 4 PM PST this afternoon CAZ072.

&&

$$