Avalanche Forecast

Issued: Mar 7th, 2013 5:41PM

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

tim haggarty, Parks Canada

Waterton Lakes.

Very little wind in the last few days has allowed for great skiing however a great deal of snow is available to transport. If the winds increase slabs will build and the hazard will rise accordingly.

Summary

Weather Forecast

Friday: Ridge builds with N flow. Clearing afternoon warming, freeze level 1500m, -10 overnight. Calm to light winds. Saturday Mainly clear. Freeze level 1500m, -6 overnight. Winds increase to moderate West. Sunday Increasing cloud, flurries late in the day. Freeze level 1500m, warming with little recovery Sunday night. Winds moderate west.

Snowpack Summary

20-35cm of HST sluffing in steep terrain. Sun crust down 20-35 cm on steep E and S aspects. March 3 rain crust present up to 2000m now buried 65cm at Treeline and producing Mod to Hard resistant shears in some locations.

Avalanche Summary

Widespread loose dry avalanches were observed today as the new snow failed in steep terrain. Some of these events reached size 2 and the majority occurred in North and East facing terrain. Earlier in the week, there were a few slabs running on suncrusts as well as a few soft slabs triggered by sluffs in N and E facing terrain.

Confidence

Problems

Loose Dry

The new snow sluffs easily in steep terrain and will run fast and far over buried crusts. This will likely decrease over the next few days as it settles but in the meantime manage your group carefully especially in confined terrain.

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

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Storm Slabs

The snow from the last two storms is forming a slab. Things are a bit touchier over crusts right now. Both heating and wind will encourage slab development over the next few days. Use caution in steep or unsupported terrain.

Choose well supported terrain without convexities.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2

Cornices

Over the last week warm moist storms added significantly to already large cornices. One large cornice failure above Forum lake scoured the entire face to the lake. With the expected sunny days in the forecast keep these in mind.

Do not travel on slopes that are exposed to cornices overhead.

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

Elevations: Alpine.

Likelihood

Likely

Expected Size

1 - 2

Valid until: Mar 10th, 2013 5:00PM