Avalanche Forecast

Issued: Apr 19th, 2013 4:00PM

The alpine rating is below threshold, the treeline rating is below threshold, and the below treeline rating is below threshold. Known problems include Loose Wet, Wind Slabs and Cornices.

tim haggarty, Parks Canada

Waterton Lakes.

We are at the end of our regular forecast season however AVALANCHE HAZARD WILL PERSIST. Generally, hazard will be higher with heating from rain or sun and will be lowest during cool periods. Spring storms may also bring additional snow.

Summary

Weather Forecast

NOT PROVIDED FOR THE EXTENDED PERIOD. Visitors may call Waterton Lakes National Park Reception on weekdays at 403 859 2224 for more detailed information. Generally: watch freezing levels closely to determine where and when heating and weakening of the snowpack is likely by the sun and rain. If more snow arrives watch the bond to the surface crusts.

Snowpack Summary

The storm that ended on Tuesday brought 30 to 70cm of low density snow over the previous April 7 and 11 crust layers. The sun came out Wed and rapid heating has formed surface crusts on most slopes except for high steep North. Since Wednesday ridge top winds from the South have built windslabs treeline and above.

Avalanche Summary

A few slabs out of open terrain near treeline were seen in the last two days on East and North aspects. A great deal of loose dry activity occurred during and immediately following the last storm but this activity has settled down with the heating. Loose wet activity picked up with the heating and this will likely remain the dominant concern.

Confidence

Problems

Loose Wet

Depending upon the inputs of heat from rain or sun this activity can be expected everywhere. Travelers must carefully monitor surface snow and be clear of slopes before crusts break down. Use extra caution if there is moist snow over buried crusts.

Be alert to conditions that change with elevation.Plan to be off big slopes before the temperatures rises and the snowpack deteriorates.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Wind Slabs

There still remains some dry snow available for transport at upper elevations on some low angled slopes. Southwest winds have been redistributing this forming isolated pockets of slab. Additional snowfall may also contribute to the formation of these

Be cautious as you transition into wind affected terrain.Caution in lee and cross-loaded terrain near ridge crests.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Cornices

With warm temperatures, solar heating, or rain to upper elevations, cornice failures will occur. These are large triggers and have the potential to create larger avalanches. Minimize your exposure during rapid warming or loading.

Pay attention to overhead hazards like cornices.Cornices become weak with daytime heating.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Valid until: Apr 22nd, 2013 4:00PM