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Avalanche Forecast

Archived

Jan 22nd, 2014–Jan 23rd, 2014

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

Regions

South Rockies.

Confidence

Fair - Timing or intensity of solar radiation is uncertain

Weather Forecast

A ridge of high pressure will continue to dominate the region bringing mainly clear skies and dry conditions for the forecast period. On Thursday the freezing level should hover at about 1500m, but another inversion will set in for Friday and Saturday with above freezing alpine temperatures. Winds should remain mainly light and west/northwesterly for all three days.

Avalanche Summary

Isolated wind slabs to size 1.5 were reported to have been triggered in the Elk Valley South area. They occurred in response to new snow on Tuesday night.

Snowpack Summary

Light amounts of new snow overlie a variety of surfaces which include: old, stubborn wind slabs in exposed terrain, well developed surface hoar in sheltered areas or a melt-freeze crust on steep, previously sun-exposed slopes. In exposed terrain, the new snow may have been distributed into small windslabs. The main concern in the region appears to be weak buried facet crystals. The facet layer, which exists in the mid or lower snowpack (depending where you are in the region), was responsible for some serious close calls last week. Although activity at this interface has tapered-off, this persistent problem has potential to re-awaken with warming forecast for the next few days. Other possible triggers for this layer include cornice fall, or a heavy load over a thin spot.

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.

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.