Avalanche Forecast

Issued: Apr 15th, 2015 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 Wind Slabs and Cornices.

grant statham, Parks Canada

Banff Yoho Kootenay.

A beautiful day in the mountains, and strong winds aloft kept the snow surface mostly cool except in sheltered, south facing areas. Next few days - classic SPRING conditions. Start early and finish early as we transition into melt/freeze conditions.

Summary

Weather Forecast

A strong ridge of high pressure is settling into the region and the next 5 days look to be sunny and warm. Spring is here! Expect highs over the next few days between 5 and 10 degrees, and freezing levels will hit 2300m on Friday. Winds will generally be light at treeline, but will continue to smoke along between 35-60 km/hr at high elevations.

Snowpack Summary

Last 5 days of storm snow totalled 35cm at Bow Summit, 49 cm at Lake Louise and 32cm at Sunshine. Strong winds have blown this snow into windslabs at treeline and above, and now the solar influence will weaken the snowpack structure in the afternoon. Cornices are a major concern (see avalanche activity) and seem to be waking up the deep facets.

Avalanche Summary

A large (size 3) slab avalanche triggered by a cornice fall was observed on the Simpson Ridge, beyond the Sunshine backcountry. Also, a pair of skiers triggered a size 2 avalanche on the obviously windloaded roll to the north of Quartz Ridge - this one could have been predicted as that is a fat, convex roll. Generally the wind kept the snow cool.

Confidence

Problems

Wind Slabs

Windslabs exist in many open areas at treeline and above, and expect to see these avalanche during the warm afternoons as the sun effects the snow surface. Watch out for all windloaded rolls.

Be careful with wind loaded pockets, especially near ridge crests and roll-overs.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Cornices

Another large cornice fall was observed on Wednesday, triggering a size 3 deep slab. The deep facets at the base of the snowpack appear to be waking up with large triggers.

Stay well back from cornices.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 3

Valid until: Apr 16th, 2015 4:00PM