Avalanche Forecast

Issued: Feb 18th, 2019 4:44PM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is moderate. Known problems include Persistent Slabs and Wind Slabs.

Avalanche Canada kdevine, Avalanche Canada

Wind slabs at upper elevations, and persistent slabs at lower elevations remain a concern as they can be triggered by humans. A cautious approach to backcountry travel is recommended.

Summary

Confidence

High -

Weather Forecast

MONDAY NIGHT - cloudy with clear periods / southwest winds 10-20 km/h / alpine low temperature near -15TUESDAY - Mainly cloudy with flurries, 2-4 cm / southwest winds 10-25 km/h / alpine high temperature near -10WEDNESDAY - A mix of sun and cloud / north winds 10-20 km/h / alpine high temperature near -9THURSDAY - Mainly sunny with cloudy periods / northwest winds, 10-15 km/h / alpine high temperature near -13

Avalanche Summary

On Sunday, several natural and human triggered wind slab avalanches up to size 2 were reported. Several natural loose snow avalanches were reported on steep solar terrain, size 1.5-2.5.On Saturday, skiers triggered a few small (size 1) storm slabs and wind slabs as well as one larger (size 2) persistent slab avalanche. The persistent slab avalanche was triggered on a north aspect at 2100 m and failed on a 60 cm deep surface hoar layer. On Friday, a few size 1.5 persistent slab avalanches were were remotely triggered on north aspects at treeline, failing on 40-60 cm deep surface hoar layers. Some larger (size 2) persistent slab avalanches were triggered on the same layers just outside the region boundary. More persistent slab activity occurred earlier in the week, predominantly on northeast aspects between 1200 and 1900 m.

Snowpack Summary

10-15 cm of low density snow has been blown around by recent strong northerly winds, creating reverse-loading on some slopes. Two prominent weak layers have been responsible for several dangerous avalanches in the past two weeks. The upper layer was buried at the end of January and lies approximately 40 cm below the surface. The deeper one was buried mid-January and lies approximately 75 cm below the surface. Both consists of a mix of surface hoar (feathery crystals) and facets (sugary snow) and may lie on top of a sun crust on southerly aspects. Both layers are potentially reactive and in any given location, one or both could exist in the snowpack. Wide propagation has been noted, meaning avalanches have the potential to be large (up to size 3). These weak layers are most prevalent at treeline and below, but may also be found in sheltered areas in the alpine.Average snow depths are approximately 300 cm. Very sporadically, failures have occurred near the base of the snowpack in this region, or in neighboring regions. These releases have almost all been from high alpine areas, possibly triggered close to rocky features.

Problems

Persistent Slabs

An icon showing Persistent Slabs
There are two persistent weak layers in the snowpack, buried approximately 40 cm and 75 cm below the surface. Activity is most pronounced at treeline elevations.
Any steep opening in the trees should be treated as suspect.Avoid convexities as well as steep, open and/or sparsely treed slopes at and below treeline.

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

Likelihood

Possible

Expected Size

2 - 3

Wind Slabs

An icon showing Wind Slabs
Wind slabs have formed on various aspects as the wind has shifted direction over the past few days.
Use ridges or ribs to avoid pockets of wind loaded snow.Avoid freshly wind loaded features.If triggered, wind slabs may step down to deeper layers and result in even larger avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Feb 19th, 2019 2:00PM

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