Avalanche Forecast

Issued: Feb 18th, 2019 4:00PM

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

adam greenberg, Parks Canada

Waterton Lakes.

Wind slabs will continue to form on all aspects as winds change throughout the forecast period. Ski quality below treeline is excellent.

Summary

Weather Forecast

Tuesday: Cloudy with isolated flurries, increasing moderate winds from the SW. Alpine High -13.Wednesday: Cloudy with isolated flurries, with winds switching to NE gusting to 40km/h. Alpine High -9Thursday: Mix of sun and cloud. Light NE winds and an alpine high of -15

Snowpack Summary

25-40cm of recent snow formed windslabs from moderate SW winds over the past week that are now buried and difficult to identify. More recent N winds have also formed slabs immediately below ridge crests. The midpack is strong in deep snowpack areas but this increase in loading will stress the weak, facetted basal snowpack.

Avalanche Summary

Evidence of natural windslabs from the storm was seen on a field trip to Cameron Lake area on Monday, with a few more natural recent loose dry avalanches out of steep rocky terrain. Surrounding operations have been seeing natural and skier triggered windslabs to size 1.5.

Confidence

Due to the number and quality of field observations

Problems

Wind Slabs

Wind slabs will continue to develop on all aspects with winds switching from W to NE on Wednesday.

Use caution in lee areas. Recent wind loading has created wind slabs.Keep an eye out for reverse loading created by N-NE winds.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Deep Persistent Slabs

A layer of weak facets is lurking at the bottom of the snowpack. This new snow may be enough to affect this basal weakness in shallow snowpack areas.

Avoid steep convexities or areas with a thin or variable snowpack.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

2 - 3.5

Valid until: Feb 21st, 2019 4:00PM