Avalanche Forecast

Issued: Feb 19th, 2019 4:36PM

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

Human triggered avalanches remain possible at all elevations. A cautious approach to backcountry travel is recommended.

Summary

Confidence

High -

Weather Forecast

TUESDAY NIGHT -Mainly cloudy with scattered flurries / southwest winds 10-20 km/h / alpine low temperature near -13WEDNESDAY - A mix of sun and cloud / north winds 10-20 km/h / alpine high temperature near -11THURSDAY - A mix of sun and cloud / west winds 10-20 km/h / alpine high temperature near -13FRIDAY - Mainly cloudy with flurries, 2-4 cm / southwest winds, 15-35 km/h / alpine high temperature near -11

Avalanche Summary

On Monday a few size 1-1.5 wind slab avalanches were reported, and some loose dry avalanches to size 1.5 were also reported. One notable report from Monday was of a size 2 natural persistent slab avalanche on a northeast aspect at 2000 m. This avalanche occurred on the persistent weak layer that was buried in January. Natural avalanche activity on this layer has mostly tapered off, so this came as a surprise to the observer.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.

Snowpack Summary

10-15 cm of snow has been blown around by recent strong northerly winds, forming wind slabs in alpine and treeline terrain.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. 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. Avalanche activity on these layers has been most pronounced at treeline and below treeline.
Avoid convexities as well as steep, open and/or sparsely treed slopes at and below treeline.Any steep opening in the trees should be treated as suspect.

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.
If triggered, wind slabs may step down to deeper layers and result in even larger avalanches.Avoid freshly wind loaded features.Use ridges or ribs to avoid pockets of wind loaded snow.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Feb 20th, 2019 2:00PM

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