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Avalanche Forecast

Archived

Dec 12th, 2020–Dec 13th, 2020

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

Jasper.

Despite the lack of natural activity, there is a lot of new snow present. Remember Moderate means human triggering remains possible and it is wise to assess each slope.

Weather Forecast

Sunday is clouds, sun, and flurries, trace snow, -11 and light Southwest winds. Monday will be similar. Tuesday may bring 5cm of snow, colder temperatures, and gusting 40km/hr Southwest ridge winds.

Snowpack Summary

40cm of storm snow from Dec 8th remains soft, continues to stabilize and settle. Wind-slabs only formed at exposed ridgetop features. The new snow overlies a variety of surfaces ranging from firm snow to surface facets and crusts on steep solar aspects. The depth of the Nov 4th rain crust is 60-80cm down and caps basal facets and depth hoar.

Avalanche Summary

No patrol on Saturday and nothing new reported. Thursday and Friday's patrols observed no new avalanches and visibility was excellent. Wednesday noted numerous loose dry natural avalanches size 1.5 on steep alpine slopes and explosive control released only a few slab size 2 and one size 3 on a NE alpine feature. 

Confidence

Due to the number and quality of field observations

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.