Avalanche Forecast

Issued: Mar 31st, 2017 4:00PM

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

conrad janzen, Parks Canada

Banff Yoho Kootenay.

It looks like a warm, windy, stormy day on Saturday. It is probably a good day to stay conservative with your terrain choices, and minimize exposure to overhead hazard. Recently any small changes in weather inputs have triggered large avalanches.

Summary

Weather Forecast

Between 5 and 10cm of snow is forecast for Saturday with strong west winds. Freezing levels will hover between 1600 and 2000m with valley highs in the East around 10'C. A cooling and clearing trend will start on Sunday.

Snowpack Summary

10-20 cm of recent snow sits over a firm 100 cm+ slab which rests precariously over the weak basal facets at all elevations. Tests show easy to moderate sudden collapse results in these facets. The surface snow is of a mix of soft snow in the shade, sun crust on sun exposed slopes in the alpine, and melt-freeze or isothermal snow below treeline,

Avalanche Summary

A few loose wet slides were reported on Friday from the local ski areas. These occurred below treeline on South and West aspects in steep terrain as the day warmed up.

Confidence

Freezing levels are uncertain on Saturday

Problems

Deep Persistent Slabs

The snowpack throughout the region has a weak base and remains suspect. Approach all avalanche terrain with suspicion and exercise conservative route choices. This problem will persist for the foreseeable future.

Be wary of slopes that did not previously avalanche.Be aware of thin areas that may propogate to deeper instabilites.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 4

Wind Slabs

With the forecast winds and new snow we expect new wind slabs to form in the alpine and cornice growth to increase. Watch for fresh wind loading near ridge crests, and avoid areas exposed to cornices.

If triggered the wind slabs may step down to deeper layers resulting in large avalanches.

Aspects: North, North East, East.

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Apr 1st, 2017 4:00PM