Avalanche Forecast

Archived

Nov 29th, 2015–Nov 30th, 2015

Alpine

Below Threshold.

Treeline

Below Threshold.

Below Treeline

Below Threshold.

Alpine

Below Threshold.

Treeline

Below Threshold.

Below Treeline

Below Threshold.

Alpine

Below Threshold.

Treeline

Below Threshold.

Below Treeline

Below Threshold.

Regions

Purcells.

Warm temperatures on solar aspects in the alpine are the prime concern these days. Use caution on sun affected slopesIf you are traveling in the backcountry, share your observations through the MIN

Confidence

Fair - Due to the number and quality of field observations

Weather Forecast

A dry ridge of high pressure continues to dominate the weather pattern over western Canada and is not forecast to move out of the area until Tuesday or Wednesday next week. In the meantime, an above-freezing layer (AFL) of air persists in the region between 1500 and 3000etres bringing temperatures in that elevation band to as high as +7°c., with its effect more pronounced on solar aspects. Arctic air pooling in the valley bottoms will keep the temperatures well below freezing until the next storm system flushes out the cold air.

Avalanche Summary

Loose snow sluffing in steep north facing terrain has been reported. No reports of wind slab avalanche activity from yesterday. Some sluffing in steep south facing terrain.

Snowpack Summary

The snowpack is extremely variable at this time. Wind scoured north facing slopes exist at treeline and above from the recent strong winds associated with the arctic front. South facing slopes have wind slabs at tree line and above and may be hiding surface hoar from the previous spell of cold clear weather. Surface facetting has been observed in the region as a result of the recent cold weather and clear skies, and surface hoar up to 20mm has been reported in sheltered locations below treeline! There are a number of surface hoar layers now buried in the snowpack, but at present they appear to be unreactive, the most recent having been buried on Nov 24th. In shallow snowpack areas, especially on northern aspects, there may be a weak facetted layer at the base of the snowpack. Recent warming at upper elevations will change the snowpack on all aspects, and especially those facing to the south. Expect suncrust on all solar aspects

Problems

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.

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.