Avalanche forecast

Bridgeport Avalanche Center

Bridgeport Avalanche Center
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Avalanche danger

Sat
Alpine
4 · High
Treeline
4 · High
Below
4 · High
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Highlights

Gale-force wind and intense snowfall rates today will create dangerous avalanche conditions in the mountains. Large naturally triggered avalanches are likely today.  A blizzard warning and an avalanche watch are in effect, intense amounts of blowing snow and reduced visibility is expected.  Travel in and around avalanche terrain is not recommended.  

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    1–2.5

    Gale force wind and new snow will form wind slabs today. With intense snowfall rates and wind forecasted to be very strong down to valley floors, we could see wind slabs forming below the treeline. Gusts over 100 mph can create turbulent conditions loading up snow in leeward terrain, below ridges, on slopes that are prone to cross-loading, or within catchment areas.  Visible clues such as wind pillows, cornices, and scoured slopes help indicate which direction the wind is coming from and which slopes are being loaded with snow. 

    (2/27/2024)

    Rider and machine triggered a wind slab in north-facing terrain in McKay Creek.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    1–2.5

    Storm Slabs are likely to form on all aspects in and below the treeline today. Intense snowfall rates of 2-5 inches an hour are forecasted throughout the day and into the evening. The rapid accumulation of snow may not have enough time to bond to itself.  A subtle change in temperature through the day or graupel that gets buried during the loading event can be a factor within storm slab instabilities.  The sound of a 'Whumph' as the snow settles or collapses is an indicator of unstable snow. On steeper slopes shooting cracks could be visible. If traveling in low-angle terrain (slopes generally less than 30 degrees) or through flat terrain on a storm day, stay aware of your surroundings and avoid being in or around avalanche terrain or runout zones. 

Avalanche Discussion

After a week of warm and sunny spring-like conditions, a major weather pattern change is underway. With good travel conditions from this past week, people were out in the mountains venturing into north-facing Alpine terrain. We received a report of a human-triggered wind slab in the Virginia Lakes area and a snowmobile-triggered avalanche in the BWRA. The terrain and fracture characteristics were similar in that the fracture initiated mid-way down the slope in an isolated terrain feature (D1.5-R2) See the photo below from the BWRA, no photo from Virginia Lakes. There was evidence of wind stripping as well as wind loading across the forecast area. A high degree of spatial variability was present creating a mixed perspective depending on where you traveled. The relatively stable conditions and good weather led to travel within complex north-facing Alpine terrain, no injuries were reported from either of the slides. A hard slab on the surface can produce a false sense of security as skis or a machine's track are not able to penetrate into the surface snow at times. 

The big shift out of the spring-like weather began on Thursday with increased wind on the Sierra Crest mixing down to valley floors along HWY 395. Precipitation began yesterday and SNOTEL sites in our forecast area are beginning to show accumulation numbers. The majority of the new snow is expected to start today and continue throughout the weekend. The Sierra Crest could receive upwards of 5-10 feet of snow and liquid SWE (Snow water equivalent) upwards of 5-10" of water. 

Blizzard-like conditions and a High avalanche danger rating will create dangerous travel conditions in the mountains. Blizzard-like conditions greatly reduce our spatial awareness in the mountains and blowing snow with little to no visibility can easily disorient people. With the large amounts of new snow, we could see avalanches traveling down into below-treeline terrain. Take caution when traveling in these stormy conditions to ensure you are not near avalanche terrain or runout zones. 

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