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Avalanche Forecast

Archived

Apr 12th, 2022–Apr 13th, 2022

Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely.
Treeline
Natural avalanches unlikely.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely.
Treeline
Natural avalanches unlikely.
Below Treeline
Natural avalanches unlikely.

Regions

Purcells.

Small wind slabs are expected to remain reactive on Wednesday. Wind direction has been variable and wind slabs should be expected on all aspects in exposed high elevation terrain.

Confidence

Moderate - Uncertainty is due to the limited number of field observations. Uncertainty is due to the speed, direction, or duration of the wind and its effect on the snowpack.

Weather Forecast

Tuesday night: Partly cloudy, light to moderate northeast wind, treeline low around -15 °C.

Wednesday: Mainly cloudy with sunny breaks, light to moderate northeast wind, treeline high around -8 °C.

Thursday: A mix of sun and cloud, light east wind, treeline high around -6 °C.

Friday: A mix of sun and cloud, light variable wind, treeline high around -4 °C.

Avalanche Summary

On Sunday, a natural size 1.5 wind slab was observed on an east aspect at 2400 m which was 30 cm thick. Two natural cornice releases were also observed on northeast aspects which triggered slabs on the slopes below. Explosives triggered three cornices on north and east aspects between 2100 and 2600 m. Two of these triggered small wind slabs on the slopes below. 

Observations are limited this time of year. If you are getting out in the backcountry, please consider contributing to the Mountain Information Network.

Snowpack Summary

10-30 cm of recent snowfall has buried a widespread melt-freeze crust which formed during the major warming event at the end of last week. Recent moderate to strong winds have redistributed the recent snow forming reactive wind slabs in exposed terrain at higher elevations. The recent wind direction appears to have been variable across the region with mainly southwest wind in the north of the region and mainly northeast wind in the south of the region. 

A thick rain crust with facets above from early December is buried around 100-200 cm deep. Large avalanches were naturally triggered on this layer during the last significant warming event in the western part of the region near the Bugaboos. With the current cold temperatures, avalanche activity on this layer is unlikely. However, we expect it will wake up again with the next major input of warming and sun, or rainfall.

Terrain and Travel

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Recent wind has varied in direction so watch for wind slabs on all aspects.
  • Wind slabs may be poorly bonded to the underlying crust.
  • When a thick, melt-freeze surface crust is present, avalanche activity is unlikely.
  • Cornices often break further back than expected; give them a wide berth when traveling on ridgetops.

Problems

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.