Avalanche Forecast

Issued: Feb 20th, 2019 4:31PM

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

Though avalanche activity has slowed down, it is worth keeping in mind that the potential still exists for humans to trigger persistent slab avalanches. While these avalanches are becoming less likely, the consequences remain high.

Summary

Confidence

High -

Weather Forecast

WEDNESDAY NIGHT - Mainly clear / northeast winds 10-20 km/h / alpine low temperature near -16THURSDAY - A mix of sun and cloud / west winds 10-20 km/h / alpine high temperature near -13FRIDAY - Mainly cloudy with flurries, 5-10 cm / south wind 15-30 km/h / alpine high temperature near -13SATURDAY - A mix of sun and cloud with isolated flurries / northwest winds, 10-15 km/h / alpine high temperature near -12

Avalanche Summary

On Wednesday, there was a report of severalĀ  size 2 human triggered persistent slab avalanches. These were all triggered remotely (from a distance) and reportedly failed on a persistent weak layer that was buried mid January.On Tuesday, a few natural and human triggered wind slab avalanches to size 2 were reported, as well as loose dry avalanches to size 1.5.On Monday there were reports of several natural and human triggered avalanches to size 1.5. Several of these were triggered remotely (from a distance). Many of these avalanches were wind slabs, but several of them failed on a persistent weak layer that was buried in mid January. Numerous natural and human triggered avalanches up to size 2 were reported on Sunday. There were also two reports of persistent slab avalanches, one triggered by explosives and one occurred naturally. These were size 3 and 2.5 respectively and both occurred in the alpine on south and west aspects.

Snowpack Summary

15 to 40 cm of low density snow has fallen over the past week, with greater amounts in the south of the region. Recent northerly winds have formed wind slabs in lee areas. This snow is sitting on a surface hoar (feathery crystals) and crust layer that was buried on February 7th which could eventually develop into a problem layer.Two additional weak layers of surface hoar have produced large avalanches in the region over the past month. A layer buried at the end of January is around 40 cm deep and a layer buried mid-January is between 50 and 90 cm deep. The mid-January layer may also be associated with a crust on southerly aspects. These layers are most prominent at treeline and below. Human triggered avalanches continue to be reported on these weak layers.The remainder of the snowpack is considered generally strong. However, there have been sporadic reports of very large avalanches that have released near the base of the snowpack. Most of these avalanches have been in the high alpine. There has been about one report a week for the past month.

Problems

Persistent Slabs

An icon showing Persistent Slabs
It remains possible to trigger an avalanche on one of the surface hoar or crust layers buried 30 to 80 cm deep. These layers are most prominent at treeline and below.
Watch for whumpfing, hollow sounds, and shooting cracks.Avoid steep, open and/or sparsely treed slopes at and below treeline.Be aware of the potential for wide propagation.

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

Likelihood

Possible

Expected Size

1.5 - 2.5

Wind Slabs

An icon showing Wind Slabs
Wind slabs can be found on a variety of aspects due to previous variable wind direction.
Wind from a variety of directions has formed wind slabs in unusual locations.If triggered the wind slabs may step down to deeper layers resulting in large avalanches.Use caution in freshly wind-loaded features, especially near ridge crests and in steep terrain.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Feb 21st, 2019 2:00PM