Avalanche Forecast

Archived

Apr 21st, 2022–Apr 22nd, 2022

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

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.

Regions

Sea To Sky.

Lingering wind slabs may remain reactive to human triggers on lee features in the alpine.

Carefully evaluate steep lines for wind slabs.

Confidence

Moderate - Uncertainty is due to the limited number of field observations.

Weather Forecast

Thursday night: Mostly cloudy / Light south wind / Low of -4 / Freezing level 1000 m.

Friday: Mix of sun and cloud / Light west wind / High of 3 / Freezing level 1700 m.

Saturday: Mix of sun and cloud / Light southwest wind / High of 4 / Freezing level 1800 m.

Sunday: Cloudy / Moderate southeast wind / High of 10 / Freezing level 1700 m.

Avalanche Summary

A skier triggered size 1.5 wind slab avalanche was reported on a northwest aspect in the alpine on Wednesday.

Skier and snowmobiler triggered storm slab avalanches up to size 2 were reported on Tuesday. North and easterly aspects that had been loaded by the wind at treeline and above were the most reactive. See MINs Here and Here.

We currently have very limited avalanche observation data from this region.

Please consider posting your observations to the Mountain Information Network (MIN). Photos of current conditions and avalanches are the most helpful.

Snowpack Summary

5-10 cm of new snow adds to the 35-55 cm of recent snow. Moderate southerly winds have formed wind slabs that may remain reactive to human triggers on lee features at treeline and above.

The recent snow is sitting on a variety of hard snow surfaces, including crusts and wind scoured snow.

Below this, there are several crusts in the upper snowpack that may have the potential to produce large avalanches during the next significant warming event.

Terrain and Travel

Be careful with wind slabs, especially in steep, unsupported and/or convex terrain features.
Caution around slopes that are exposed to cornices overhead.
Back off slopes as the surface becomes moist or wet with rising temperatures.
Make observations and assess conditions continually as you travel.

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.

Cornices

Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.

Loose Wet

Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.