THIS SNOWPACK SUMMARY EXPIRED ON December 25, 2018 @ 7:01 am
Snowpack Summary published on December 23, 2018 @ 7:01 am
Issued by Ryan Lewthwaite -

bottom line:

Isolated leeward aspects N-E are wind loaded & susceptable to triggering at & near treeline. Although overall the snowpack has gained strength, it will soon change the dynamic as we accumulate new snow in the upcoming days until Christmas. Tune into the forecast for snow totals & descriptions of the avalanche hazards as it unfolds. People's gate is still the preferred snowmobile launch location, as the frozen surface of the road is dicey. Obtaining permits & submitting snow observations is the best way to show support for this motorized public sanctuary!

Avalanche Character 1: Wind Slab
Wind Slab avalanches release naturally during wind events and can be triggered for up to a week after a wind event. They form in lee and cross-loaded terrain features. Avoid them by sticking to wind sheltered or wind scoured areas.

The development of wind slabs has been pronounced on leeward facing aspects N-E. These slabs are gaining strength but are still susceptable to triggering from human travel on slopes steeper than 35 degrees. Surface clues such as pillowing, cornice formation, & textureless snow deposits should be recognized as hazardous, especially when cracking or whumphing is observed in your local area. Cornices are still unpredictable & large in size.

Snowpack Discussion

Isolated leeward aspects still hold the potential for wind slab avalanche activity. It may be stubborn to initiate but wind slabs have been found in succession through the upper layers of the pack. Two distinct melt-freeze crusts were found, with the most apparent & reactive 10cm below the snows surface. Facetting below the crust is helping the wind slab to collapse with some hard forces.

recent observations

Observations have found wind loaded slopes & cornice failures are resulting in small size avalanches. Nearly 10cm of recently deposited snow sits on a melt-freeze crust which is reactive to stability tests with hard force. Facetted snow below this crust has been the catalyst for such failures. A thin wind-skin can be found on the surface snow.

CURRENT CONDITIONS Weather observations from Sonora Pass
0600 temperature: 34 deg. F.
Max. temperature in the last 24 hours: 44 deg. F.
Average wind direction during the last 24 hours: West
Average wind speed during the last 24 hours: mph
Maximum wind gust in the last 24 hours: mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: 75 inches
weather

Clouds & sporatic snow showers will dominate the atmosphere for the next few days through the holiday. Hopeful accumulations of 6-15" are likely above 7000' with an almost certainty for high winds & possibly rain in low valley areas.

Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 8000 ft. to 10000 ft.
  Sunday Sunday Night Monday
Weather: Mostly cloudy with a slight chance of snow showers later. Snow Level @ 7000' Mostly cloudy then becoming partly cloudy with a slight chance for snow showers late. Snow Level @ 7000' Partly to mostly cloudy with snow showers. Snow Level @ 7000'
Temperatures: 36 to 42 deg. F. 22 to 27 deg. F. 35 to 41 deg. F.
Wind direction: Southwest West Southwest
Wind speed: 10 to 15 mph; gusts to 40 mph 15 to 20 mph, gusts to 45 mph 15 to 25 mph; gusts to 35 mph increasing to 50 mph later
Expected snowfall: 0 in. 1 in. 2 to 3 in.
For above 10000 ft.
  Sunday Sunday Night Monday
Weather: Mostly cloudy with a slight chance of snow showers later. Snow Level @ 7000' Mostly cloudy then becoming partly cloudy with a slight chance for snow showers late. Snow Level @ 7000' Partly to mostly cloudy with snow showers. Snow Level @ 7000'
Temperatures: 30 to 35 deg. F. 18 to 23 deg. F. 28 to 33 deg. F.
Wind direction: West West West
Wind speed: 15 to 30 mph; gusts to 45 mph 25 to 40 mph decreasing to 20 to 30 mph; gusts to 60 mph 20 to 35 mph; gusts to 45 mph increasing to 60 mph later
Expected snowfall: trace in. 1 in. 2 to 3 in.
Disclaimer

This snowpack summary applies only to backcountry areas in the Bridgeport Winter Recreation Area. Click here for a map of the area. This snowpack summary describes general avalanche conditions and local variations always occur. This snowpack summary expires in 48 hours unless otherwise noted. The information in this snowpack summary is provided by the USDA Forest Service who is solely responsible for its content.