Avalanche Forecast

Archived

Apr 22nd, 2022–Apr 23rd, 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

Sea To Sky.

Large cornice failures are more likely during periods of hot and sunny weather. Use caution when traveling on corniced ridgetops and limit your exposure to slopes with large cornices overhead.

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

Confidence

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

Weather Forecast

Friday night: Partly cloudy / Light west wind / Low of -4 / Freezing level 1200 m.

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

Sunday: Sunny in the morning, then increasing cloud throughout the day and 10-15 cm snow overnight ( rain below around 1200 m) / Moderate south wind / High of 3 / Freezing level 1700 m.

Monday: Cloudy / Moderate southwest wind / High of 2 / Freezing level 1500 m.

Avalanche Summary

Several naturally triggered storm slab avalanches up to size 1.5 were reported on lee features in the alpine Thursday morning near Whistler.

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

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

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. In areas where there are weak facets sitting on top of the crusts, there is potential for large natural avalanches when freezing levels reach mountain tops for multiple days.

Avoid large slopes and avalanche paths during periods of intense warming.

Cornices are very large and more prone to failure during periods of intense warming.

Terrain and Travel

Caution around slopes that are exposed to cornices overhead.
Be careful with wind slabs, especially in steep, unsupported and/or convex terrain features.
Back off slopes as the surface becomes moist or wet with rising temperatures.
Avoid exposure to steep sun exposed slopes.

Problems

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.

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.

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.