Avalanche Forecast

Issued: Apr 6th, 2017 4:33PM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is moderate. Known problems include Storm Slabs, Loose Wet and Deep Persistent Slabs.

jonas hoke, Parks Canada

Waterton Lakes.

Ongoing warm temperatures in the upper elevations will be putting the entire snowpack to the test over the next couple of days. Best to wait for the next bout of cooler weather for any bigger objectives.

Summary

Weather Forecast

Friday: Snow/rain (10-20cm). Ridge wind strong-extreme SW. Alpine temps, Low 0, High 3. Freezing level 2500m.Saturday: Cloudy, PM flurries. Ridge wind mod-light SW. Alpine temps, Low -8, High -1. Freezing level 2000m.Sunday: Models disagree, possible snow/rain (0-40cm), Ridge wind light N. Alpine temps, Low -5, High -2. Freezing level 1600m.

Snowpack Summary

Minimal surface crust recovery with freezing levels staying above 2000m overnight. Incoming warm snow with wind will likely form slabs quickly. As snow transitions to rain watch for surface instabilities to become reactive quickly. Basal facets persist in some areas, and may become reactive to large triggers as a result of ongoing warm temps.

Avalanche Summary

Numerous small to large (up to size 2.0) natural loose wet avalanches were observed on Thursday by neighboring operations, these occurred on all aspects and at all elevations.

Confidence

Forecast snowfall amounts are uncertain

Problems

Storm Slabs

Incoming snow and wind will likely form slabs. These will become particularly touchy if snowfall turns to rain.

Use caution on open slopes and convex rolls Use caution in lee areas. Wind loading could create slabs.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Loose Wet

New snow over old crusty surfaces will likely produce small natural avalanches with daytime warming or when rainfall commences.

Watch for clues, like sluffing off of cliffs, that the snowpack is warming up. Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Deep Persistent Slabs

Cornices are large and continue to build with warm temps and wind. Incoming rain/snow on Friday may be the trigger that causes cornices to fail, which may in turn trigger deep persistent weak layers in large open terrain.

Be wary of large alpine slopes that did not previously avalanche.Minimize overhead exposure during periods of heavy loading from new snow, wind.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely

Expected Size

3 - 4

Valid until: Apr 9th, 2017 4:00PM