Avalanche Forecast

Issued: Mar 29th, 2013 4:00PM

The alpine rating is moderate, the treeline rating is low, and the below treeline rating is low. Known problems include Loose Wet, Persistent Slabs and Cornices.

chris gooliaff, Parks Canada

Banff Yoho Kootenay.

The spring cycle is in full effect right now. Danger ratings on solar aspects will increase with daytime warming to considerable/high, so start early and be back at the trail-head before the heat of the day!

Summary

Weather Forecast

Temperatures will be above normal, with freezing levels hitting 2200m tomorrow and possibly 2700m on Sunday. We may see scattered clouds later in the afternoon, but there shouldn't be any precipitation associated with them. Winds will be light from the NW.

Snowpack Summary

W of divide. S through W slopes developing variable melt freeze crusts, thickest on steep W aspects.Â Powder snow on N aspects. Generally well settled snowpack.E of divide settled wind slabs over basal facets. Supportive travel with variable sun crust up to 2700m.

Avalanche Summary

Natural cornice release off Wapta Peak near Mt Field this morning, good size 2 pulling small slab below and creating a large powder cloud. See photo here. A size 3 slab off a south aspect was noted in the drainage north of Mt Bourgeau. This likely failed on a sun crust, but scrubbed down to ground lower in the runout.

Confidence

The weather pattern is stable

Problems

Loose Wet

Occurring in the afternoons, activity has been mainly isolated to very steep slopes at tree-line and below. Higher freezing levels this weekend may bring more activity in the alpine.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.Finish ice climbs early in the day before the temperature rises.

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

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Persistent Slabs

In shallow snowpack areas, particularly east of the divide, whumphing has subsided. However, recent avalanche activity from cornice falls and warm temperatures shows it is still a layer to be respected, especiallly on solar aspects

Be aware of the potential for full depth avalanches due to deeply buried weak layers.Watch for clues, like sluffing off of cliffs, that the snowpack is warming up.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Cornices

Cornice failures have increased in number as the freezing levels rise. They may trigger an avalanche, or be an avalanche themselves in couloirs.

Cornices become weak with daytime heating, so travel early on exposed slopes.Make your travel plans to take advantage of overnight freezing.

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

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

2 - 3

Valid until: Mar 30th, 2013 4:00PM