Avalanche Forecast

Issued: Feb 23rd, 2019 4:00PM

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

adam greenberg, Parks Canada

Waterton Lakes.

Recent snow has formed a slab overloading weak snow below treeline. This problem is compounded by the newly burnt forest, allowing wind to stiffen the snow all the way to valley bottom.

Summary

Weather Forecast

Saturday: Mix of sun and cloud with light Northeast winds. Alpine High -15Sunday: Sunny with cloudy periods, light East winds. Temperature inversion, with an Alpine high of -19.Monday: Cloudy with isolated flurries, with up to 10cm on the front ranges, and less along the divide. Alpine high of -18

Snowpack Summary

The midpack remains strong in deep snowpack areas, but is acting as a slab above deep weak layers in shallower areas that is reactive skiers mainly at below treeline elevations where melt freeze crusts have been preserved. Continued snowfall on Saturday is burying windslabs formed by recent Westerly winds.

Avalanche Summary

We received a second hand report of skier triggered avalanches below treeline on Mt. Bertha on Thursday failing on facets above a crust deep in the snowpack, or basal facets. A natural size 2 slab was also observed below treeline in a steep and shallow snowpack feature in the Cameron Lake area that failed on similar weak layers earlier in the week.

Confidence

Problems

Wind Slabs

Winds slabs formed from recent W winds have now been buried by Saturdays snowfall and may be hard to detect.

Use caution in lee areas. Recent wind loading has created wind slabs.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Deep Persistent Slabs

Recent snow has been enough to create a slab over deep instabilities below treeline where the snowpack is shallow and weak, and melt freeze crusts have been preserved. These were reactive to skier traffic on Mt. Bertha on Thursday.

Avoid thin, rocky or unsupported slopes.Avoid steep convexities or areas with a thin or variable snowpack.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 2.5

Valid until: Feb 26th, 2019 4:00PM