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Avalanche Forecast

Archived

Nov 12th, 2018–Nov 13th, 2018

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

Regions

Little Yoho.

Good ski conditions exist if you are in high, smooth terrain, but the snowpack is thin. Watch for typical early season hazards and areas where the October 26th crust may be most reactive: shaded alpine lee areas.

Weather Forecast

The ridge of high pressure will remain for one more day with an inversion setting up. This means warmer temperatures in the alpine than in the valley bottom and the potential for valley cloud west of the divide. On Wed/Thurs, the ridge breaks down with up to 25 cm of snow by the end of day Thursday with strong westerly alpine winds.

Snowpack Summary

In the alpine, 20-50 cm of facetted and wind effected snow sits on the October 26th temperature crust. This crust is found in the alpine, mainly on shaded and lee aspects (where the October snow didn't completely melt) and has weak facets above and below. Total snowpack depths are 60-120 cm+ in the alpine, tapering quickly at treeline and below.

Avalanche Summary

Sunshine and Lake Louise ski hills reported isolated small windslabs still being triggered in steep, lee alpine terrain on Monday. On the deep persistent layer, natural and explosives triggered avalanche activity has tapered, but isolated whumphing still indicates triggering is possible.

Confidence

Timing, track, or intensity of incoming weather system is uncertain on Wednesday

Problems

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.

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.