Avalanche Forecast

Issued: Jan 22nd, 2016 7:53AM

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

pgoddard, Avalanche Canada

Purcells.

A Special Public Avalanche Warning is in effect for this region.

Summary

Confidence

Moderate - Timing or intensity of solar radiation is uncertain

Weather Forecast

A last pulse of 5-10 cm snow with easing SW winds and a 1000 m freezing level is expected on Saturday ahead of a cooling and drying trend starting Sunday morning. Cloudy skies, light winds, cool temperatures and a few flurries may give way to sunny skies on Sunday/Monday. For more details check out http://www.avalanche.ca/weather.

Avalanche Summary

Several size 1-2 wind slabs and storm slabs have been triggered naturally and by skiers and explosives this week. Some of these failed on a persistent weak layer of surface hoar or a crust/facet interface. Winds, new snow and rising temperatures increased the size and likelihood of avalanches on Friday. Human triggering remains a real possibility through the weekend.

Snowpack Summary

Conditions are variable across the Purcells. Wind slabs and storm slabs have developed at treeline and alpine elevations. In some areas, these overlie a surface hoar or crust/facet interface from early January and may be extra touchy. This persistent weak layer is around 30-60 cm down and may be just reaching tipping point in parts of the region. A more deeply buried layer of surface hoar from December is now considered dormant. In general, the mid and lower snowpack are well settled and strong.

Problems

Storm Slabs

The recent storm has created storm slabs on a variety of slopes. Touchy wind slabs also exist on slopes lee to recent southerly winds.

Travel on ridgetops to avoid wind slabs on slopes below.>Be cautious as you transition into wind affected terrain.>Choose conservative lines and watch for clues of instability.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 4

Persistent Slabs

A slab has formed above a touchy buried weakness. This could be triggered by the weight of a person, even from a distance. Avalanches could be larger than expected.

Avoid open slopes and convex rolls at and below treeline, and north-facing alpine slopes, where buried surface hoar may be preserved.>Be aware of the potential for remote triggers and wide propagations.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 5

Valid until: Jan 23rd, 2016 2:00PM