Avalanche Forecast

Issued: Feb 2nd, 2018 4:34PM

The alpine rating is high, the treeline rating is high, and the below treeline rating is high. Known problems include Persistent Slabs and Storm Slabs.

conrad janzen, Parks Canada

Banff Yoho Kootenay.

We expect another natural avalanche cycle to occur starting Friday night and tapering off late on Saturday. Avoid all avalanche terrain during this time! Ski resorts and non-avalanche terrain are the places to enjoy the fresh snow right now.

Summary

Weather Forecast

Friday night and Saturday morning could see as much as 15 to 20 cm of snow in our forecast area along with moderate to strong SW winds. Later in the day we expect to see both the precipitation and winds decrease as the temperatures cool. Sunday and Monday look like scattered flurries, cool temperatures and light winds.

Snowpack Summary

5-15 cm of new snow Friday with strong SW alpine winds. The main concern in the snowpack continues to be the three persistent weak layers of surface hoar and/or facets that are found between 50 and 100cm down in the snowpack. We continue to observe sudden test results, whumphing and large propagations on these layers. Below this is a faceted base.

Avalanche Summary

Some natural activity observed Friday with a size 2.5 avalanche over Cascade Falls in Banff and some natural avalanches on Mt Stephen in Yoho but visibility was poor. Big avalanches with explosives over the last few days show that snowpack remains prime for triggering. Some avalanches ran full path and put dust or debris on roads.

Confidence

Forecast snowfall amounts are uncertain on Saturday

Problems

Persistent Slabs

Three weak layers exist in the upper snowpack: Jan 16, Jan 6, and Dec 15. All are a mix of sun crust, surface hoar and facets depending on the aspect and elevation. Destructive avalanches have occurred on these and will continue over the few days.

Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.Avoid all avalanche terrain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

2 - 3.5

Storm Slabs

If the forecasted new snow amounts of 15-20 cm with strong SW winds show up, we will likely see storm slabs failing over the next 24 hrs with potential to step down to deeper layers. Stick to non-avalanche terrain until things have a chance to settle

Avoid all avalanche terrain.If triggered the storm slabs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2.5

Valid until: Feb 3rd, 2018 4:00PM