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Avalanche Forecast

Archived

Mar 21st, 2017–Mar 24th, 2017

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

Regions

Waterton Lakes.

A strong crust is allowing fast travel Below Treeline -  for those trained and equipped for avalanche terrain, it's a good time to cover ground, and discover new areas of the Park.  Be wary of exposure to cornices, and large Alpine slopes.

Weather Forecast

Wednesday: Cloudy, Light precipitation ending in the morning. Rain/snow line at Treeline, lowering. Ridge Winds: SW, becoming Strong. Freezing level: 1950m. Treeline High 0.Thursday: Sun & cloud. Ridge winds: Moderate SW. Freezing Level: 1000m, rising to 1500m. Treeline High -5Friday: Cloudy, flurries later. Moderate SW winds. Freezing Level 1900.

Snowpack Summary

A thick crust Below Treeline overlies a Moist snowpack. The crust thins out at lower treeline elevations, with a dry, late winter snowpack in the Alpine. New snow instabilities from Saturdays's storm are settling. A crust from Mid Feb, down 1m, is giving some sudden results in tests. The bottom of the snowpack is  faceted, and still weak in places.

Avalanche Summary

No new avalanches observed on Tuesday. On Saturday, a warm storm caused a widespread cycle of Large (Size 2-3) Natural avalanches, mainly in the West where precipitation was heaviest. Many Wet Slabs initiated around 1900-2200m, some on the February 16 MFcr. Several Storm slabs & Deep Persistent slabs failed in steep, lee Alpine terrain.

Confidence

Due to the number of field observations

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.