Avalanche Forecast

Issued: Nov 25th, 2015 8:15AM

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

bcorrigan, Avalanche Canada

Purcells.

Forecasters are working with a scarcity of information at this time. Use caution in this early season snowpack and take the time to dig a pit. We'd love to hear from you if you have information to share on the Mountain Information Network. MIN

Summary

Weather Forecast

Arctic air has moved in from the north bringing clear skies and cooler than average temperatures. Strong northerly winds at ridge top are expected to continue through Thursday afternoon, and then back off to more moderate speedsby Friday after whichwinds should diminish to lighter values. Above freezing temperatures in the alpine are forecast to begin Friday morning and continue into the weekend but valley bottoms will remain well below freezing.

Avalanche Summary

One operator produced a size 2 avalanche with explosives on a N slope at 2300m. There have also been reports of skier controlled size 1's, 15 to 20cm storm slabs failing on the Nov 23rd surface hoar

Snowpack Summary

Monday's storm snow fell on a variety of old surfaces including crust, surface hoar and old settled snow. Arctic air moving into the region has resulted in northerly winds which have formed small wind slabs on south facing features near ridge top. Warm temps and strong solar input formed a crust on south facing features which can be found underneath Monday's storm snow. There are at least three surface hoar layers in the snowpack buried on: Nov. 5th, Nov. 11th and Nov. 23rd. The first two have been largely unreactive. Facets may exist just above the ground on shaded slopes in the alpine.Â Warming temperaturesÂ in the alpine for later in the week may significantly change the alpine hazard

Problems

Wind Slabs

Winds out of the north are building wind slab formations on southerly features. These slabs will be most problematic immediately lee of ridge crest, but you may encounter them in the right feature at treeline as well.

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

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Deep Persistent Slabs

November weak layers may be less reactive, but it's important to remember that there may be a weak layer of crust and facets near the ground. Most likely to be found on north through east facing alpine features.

Be aware of thin areas that may propogate to deeper instabilites.>Now is a good time to dig a snow profile (or two) and figure out how the snowpack changes with aspect and elevation.>

Aspects: North, North East, East.

Elevations: Alpine.

Likelihood

Unlikely

Expected Size

4 - 6

Valid until: Nov 26th, 2015 2:00PM