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Avalanche Forecast

Archived

Dec 23rd, 2019–Dec 26th, 2019

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

Regions

Waterton Lakes.

http://www.pc.gc.ca/apps/links/goto_e.asp?destination=

This is a dangerous time. We are through the storm and natural activity has tapered off, but the potential for large avalanches running to the valley bottom remains. Remember: Considerable means human triggering of avalanches is likely.

Weather Forecast

Tuesday: Freezing levels dropping to valley bottom. Flurries throughout the day and Moderate SW winds.

Wednesday: Light winds and a mix of sun and cloud for christmas. Alpine high -9

Thursday: Cloudy with west winds increasing through the day and a mild inversion forming.

Snowpack Summary

There is a highly variable snowpack across the forecast region. Generally the snowpack is wet and thin below 1800m. Above that elevation, the Cameron Lake area received the most snow in the storm with 85-100cm since Thursday. This sits on a weak facet/crust combo that is now down 150cm. The front ranges hold a thinner more wind affected snowpack.

Avalanche Summary

A widespread natural cycle occurred this past weekend, with avalanches to size 2 in the storm snow and some larger ones failing on deep persistent weak layers. A size 3 natural avalanche occurred on Mt Bertha early Sunday morning covering the Bertha Falls trail in debris, and a similar avalanche was seen on Mt. Crandell.

Confidence

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.

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.