Avalanche Forecast

Issued: Apr 13th, 2013 4:00PM

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

tim haggarty, Parks Canada

Waterton Lakes.

Recent storms have brought a return to winter conditions. Keep an eye on the weather for rapid changes in temps and precip. Carefully monitor the snowpack for signs of instability and be aware of conditions changing with both elevation and aspect.

Summary

Weather Forecast

Freezing Levels below 1400m and mainly cloudy skies with intermittent light snowfall is expected for the period. Winds will be mainly out of the North.

Snowpack Summary

Several recent storms have deposited significant amounts over the well established crusts from the warming event at the start of the month. Most of these snowfall events have been followed by periods of sunshine that have re-established crusts on solar aspects. Below 1600m rain and warm temperatures have kept the snowpack warm and crusts are weak.

Avalanche Summary

Minor DRY LOOSE events have been seen on steep N aspects TL and above. Several small LOOSE WET cycles have occurred on solar aspects as new snow is heated over underlying crusts. Despite cooler temps, evidence of recent CORNICE FAILURES indicates that the sagging cornices that remain are weak and will not take much encouragement to fall.

Confidence

Intensity of incoming weather systems is uncertain

Problems

Storm Slabs

With mild spring temperatures and variable winds, new snow quickly settles into a slab. With sun and temperature crusts as a firm bed surface the bond of this new snow should be examined carefully before committing to steep or unsupported terrain.

Make observations and assess conditions continually as you travel.Avoid freshly wind loaded features.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Loose Dry

New snow from recent and incoming storms will fail easily in steep terrain with skier traffic and naturally from extreme terrain. With underlying crusts these events may travel a long distance and gain mass. Manage your group carefully.

On steep slopes, pull over periodically or cut into a new line to manage sluffing.Be very cautious with gully features.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Cornices

Cornices are sagging and remain weak. Despite the cool temps forecast give these hazards additional respect as their roots have been eroded. Incoming wind and snow or a brief period of sunshine may be all that is needed to get these moving.

Do not travel on slopes that are exposed to cornices overhead.Extra caution needed around cornices with current conditions.

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 3

Valid until: Apr 16th, 2013 4:00PM