Avalanche Forecast

Issued: Nov 8th, 2019 4:23PM

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is below threshold. Known problems include Wind Slabs and Persistent Slabs.

lisa paulson, Parks Canada

Banff Yoho Kootenay.

Harsh weather today consisting of strong SW winds and rain to 2500 m. Few avalanches over the day, but things should improve as winds ease, temps cool, and precipitation ends Sunday morning.

Summary

Weather Forecast

Treeline temperatures should cool to just below zero and winds will ease to moderate from the SW through through tonight and Saturday. Only light snow is forecasted for Saturday. Another hit of snow is forecasted for Sunday as the arctic air moves in causing temperatures to plummet to -15C through the day. We should see an improving trend.

Snowpack Summary

Warm temperatures & rain have left moist surface snow to 2500 m. Treeline snow depths range from 50-70 cm deep (up to 110 cm in lee areas). The October crust in the lower snowpack has been the failure in recent skier involvements.

Avalanche Summary

Recent explosive control triggered windslabs to size 2.0. One explosive triggered slab on Mt. Stephan, stepped down to near glacial ice resulting in a size 2.5 avalanche. Earlier this week there were 2 skier triggered avalanches (see the MIN). Today, a few loose wet avalanches to size 1.5 were observed in the Little Yoho region (Mt Denis climbs)..

Confidence

Intensity of incoming weather systems is uncertain

Problems

Wind Slabs

Strong West - Southwest winds and the new snow has created pockets of wind slab treeline and above. Watch for wind affected areas in steep terrain while climbing or skiing.

Be careful with wind loaded pockets, especially in steep confined alpine terrain.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Persistent Slabs

A thin crust exists in the lower snowpack and has been the failure plane for a few skier accidental avalanches in the past 4 days to size 2.0. This layer has been recently loaded by wind, rain, and snow and may be reactive on steeper features.

Convex features and steep unsupported slopes will be most prone to triggering.
Remote triggering is possible, watch out for adjacent slopes.