Avalanche Forecast

Issued: Jan 26th, 2016 8:31AM

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.

triley, Avalanche Canada

Purcells.

Strong winds and rising freezing levels are pushing the danger ratings up. Conservative terrain choices without overhead hazards are recommended at this time.

Summary

Confidence

Moderate

Weather Forecast

Clouds and light snow overnight combined with increasing westerly winds. Freezing levels rising on Wednesday up to about 2000 metres with moderate westerly winds in the alpine. Snow starting early Thursday morning, expecting 5-10 cm during the day above 1500 metres, with rain below treeline. Gradual cooling with light wind and light snow on Friday.

Avalanche Summary

No new natural avalanches reported from Monday, however explosives control produced slab avalanches up to size 3.0. A couple of natural avalanches were reported on Sunday but most of the natural avalanches occurred on Friday and Saturday due to storm loading. While natural activity has tapered off since Saturday, the persistent slab is expected to remain reactive to human triggering for several more days. New wind slabs are developing in the alpine and at treeline.

Snowpack Summary

Conditions are widely 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 easily triggered by a skier or sledder. Reports indicate this persistent weak layer is now typically down 40 to 60cm in most areas and appears to be quite touchy in some parts of the region. A more deeply buried layer of surface hoar from December is now considered dormant. In general, the lower snowpack is well settled and strong.

Problems

Persistent Slabs

Rising freezing levels and increased loading from wind, snow, and rain, may increase the likelihood of triggering the buried weak layer of surface hoar.

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 due to a layer of buried surface hoar. >

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 5

Wind Slabs

New wind slabs continue to develop with forecast new snow and wind. Rising freezing levels may increase the likelihood of triggering these touchy wind slabs.

Avoid freshly wind loaded features. >Use ridges or ribs to avoid pockets of wind loaded snow. >Be cautious as you transition into wind affected terrain. >

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Valid until: Jan 27th, 2016 2:00PM