Avalanche forecast

Transitional

Haines Avalanche Center
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Avalanche danger

Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Highlights

Recent snowfall buried a widespread crust that formed up to 4,000'. Be on the lookout for strong over weak layering around this crust and look for other clues of slab formation, such as such as active wind loading, recent avalanches, shooting cracks, or any whumphing/collapsing. Avoid terrain features with a cohesive slab and use good travel techniques like not grouping under slopes and traveling one at a time.

Avalanche problems

  • Loose Dry

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2

    Loose, non-cohesive snow can gain momentum and build into slides large enough to bury a human. Confined to steeper angles, dry loose avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Consider consequences in steep terrain greater than 35 degrees. 

    The potential for a slab avalanche over weak facets surrounding the "end of year" (EOY) crust that is around 1 foot deep is also still possible.  Tree line to 4,000’ is the most likely elevation band to find this problem and on all aspects. Look for the new snow forming a slab either via settlement, or wind loading. Snow is readily available for transport if the incoming N-NW winds pick up. 

    Use caution around wind effected snow in exposed areas along ridgelines and in crossloaded gullies. 

Avalanche Discussion

Above freezing temperatures up to 4,000' due to an inversion at the end of the storm on 12/30 in the Transitional zone caused the formation of a thick ( 1" +/-), widespread "end of year" (EOY) melt freeze crust.  Strength of crust is variable due to  duration and intensity of the EOY event and is elevation dependent.  New snow may form slabs on the crust bed surface by either deposition/settling or wind transport and will just need a trigger to complete the recipe for an avalanche.  More unlikely is failure on the weak facets resting below the EOY. The cold temps will slow healing and drive faceting, or weakening within the weak layers. Treat these slopes as guilty until proven innocent. The weak layers above and below the crust could have widespread propagation potential and need to be assessed and tracked going forward. 

Also, from earlier this season, and now more than a meter deep, a few melt-freeze layers are present throughout the snowpack at all elevations and aspects. These layers have mostly been found to be healing but could fail and produce an unlikely though larger avalanche. Our overall warmer and wetter temperature regime this season has helped slow the development of persistent weak layers (PWL's) in the snowpack. However at higher elevations and further inland these grain types can exist, and will require continued assessment. 

The people you go out with, the way you communicate, and the way you practice risk reduction as a team throughout the day is equally important as the conditions.

Help us gather information about weather, snowpack, and avalanche activity by reading and submitting field observations. Useful observations can be anonymous and include: 

  • Natural or human-triggered avalanche activity
  • Signs of instability: Cracking, collapsing, or whumphing
  • Red Flag Weather: Precipitation, wind loading, warming temperatures and rain-on-snow
  • Surface hoar growth, snow depth, persistent weak layers, etc
  • Snow stability tests, or pit result and location, elevation, aspect, etc 

Were you caught, carried, injured or buried in a slide? We are all human and can benefit from lessons learned, please report incidents to Haines Avalanche Center staff confidentially.

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