Avalanche Forecast

Issued: Nov 24th, 2017 3:45PM

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

jsmith, Avalanche Canada

Purcells.

New snow sitting on a hard crust may have created reactive storm slabs at treeline and above. Due to limited data it is CRITICAL to supplement this information with your own observations. Please post your observations to the MIN.

Summary

Confidence

Low - Due to the number of field observations

Weather Forecast

SATURDAY: Mainly cloudy / Light southwesterly ridgetop winds / Freezing level around 1500 mSUNDAY: 5-10 cm new snow in the afternoon with an additional 5-10 cm overnight / Moderate to strong southwesterly ridgetop winds / Freezing level around 2400 mMONDAY: Cloudy with isolated flurries / Light to moderate westerly ridgetop winds / Freezing level around 1500 m

Avalanche Summary

On Thursday, no new avalanches were reported in this region. However, we currently have very limited observations in this region. Please submit your observations to the Mountain Information Network (MIN).

Snowpack Summary

A new crust was formed on Thursday as temperatures cooled and the rain soaked snow surface froze and then was covered by 15-25cm of snow at treeline and above. The new snow has created fresh storm slabs sitting on a crust. The depth of the snowpack varies greatly with elevation. Recent reports suggest the average depth is 150+cm in the alpine, 100-150cm at treeline, and decreasing rapidly below treeline where the primary hazards are rocks, stumps, and open creeks. The major feature in the snowpack is a crust which was formed around Halloween can be found approximately 100cm down at treeline elevations. However, the new surface crust will temporarily reduce the likelihood of triggering on this layer. We currently have very limited snowpack observations within this region and it is critical to supplement this information with your own observations.

Problems

Storm Slabs

15-25 cm of new snow has formed storm slabs sitting on a hard crust. These slabs will be particularly reactive in wind affected terrain.

Watch for whumpfing, hollow sounds, shooting cracks, or recent avalanches.Be cautious as you transition into wind affected terrain.Start cautiously on small slopes before gradually working up to larger objectives.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Loose Dry

New snow sitting on a hard crust will very likely create loose dry avalanches in steep terrain where the new snow has not yet settled into a cohesive slab.

Be cautious of sluffing in steep terrain, particularly where the debris flows into terrain traps.