Avalanche Forecast

Issued: Feb 11th, 2018 4:54PM

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

Avalanche Canada pgoddard, Avalanche Canada

A Special Public Avalanche Warning is in effect. Copy this link to view details: http://bit.ly/2nSOUyX

Summary

Confidence

Moderate - Intensity of incoming weather systems is uncertain on Tuesday

Weather Forecast

MONDAY: Mainly sunny, with increasing clouds late in the day. Light winds. Treeline temperature near -10.TUESDAY: 10-15 cm snow. Moderate westerly winds. Treeline temperature near -5.WEDNESDAY: Flurries. Light winds. Treeline temperature near -8.More details can be found in the Mountain Weather Forecast.

Avalanche Summary

A very large, widespread avalanche cycle was observed on Thursday, with a few events continuing on Friday. Slopes of all aspects and elevations ran full path and reached valley floor. In some cases, mature timber was smashed. These failed on all of the persistent weak layers discussed in the snowpack section. Avalanches involving only the recent storm snow were also very large. Explosives continued to produce large persistent slabs on Saturday, and a few wind-triggered slabs were also reported. The natural cycle is winding down, but human-triggering remains a real concern. You might be surprised by how large an avalanche can be triggered and how far it could run.

Snowpack Summary

Large cornices may be found. Moderate north to north-westerly winds have shifted 30-40 cm recent storm snow into wind slabs on lee slopes. This adds to an existing storm slab 1-2.5 m deep from the last couple of weeks accumulation. Sun crusts or moist snow may be found, depending on the time of day.Several persistent weak layers make up a troublesome snowpack. In the top 1.5-2.5 m of the snowpack, two surface hoar/ crust layers buried in January can be found. Expect to find one or other of these on all aspects and elevations.Deeper in the snowpack (around 200 cm deep) is a facet/crust/surface hoar layer from December, most prevalent at and below treeline.Near the base of the snowpack is a crust/facet combo, most likely to be triggered from thin spots in the alpine.All of these layers have produced large avalanches recently. The wide distribution and ongoing reactivity of these layers suggests that avoidance through choosing simple terrain is the best strategy.

Problems

Persistent Slabs

An icon showing Persistent Slabs
Several troublesome layers exist in the snowpack. Although the likelihood of triggering a persistent slab has gone down, the consequences remain very high.
Avoid the runout zones of avalanche paths. Very large avalanches have been running full path.Avoid steep convexities or areas with a thin or variable snowpack.Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 4

Wind Slabs

An icon showing Wind Slabs
Recent north-westerly winds have left behind wind slabs and cornices on lee slopes.
Travel on ridgetops to avoid wind slabs on slopes below.Give cornices a wide berth when travelling on or below ridges.

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1.5 - 3

Valid until: Feb 12th, 2018 2:00PM