Avalanche Forecast

Issued: Mar 7th, 2020 4:00PM

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

Tim Haggarty, Parks Canada

Little Yoho.

Avalanche Control is planned for Mt Whymper, the Sunshine Village access road, Mt Field and Mt Stephen Sunday March 8.

No activities in these areas please.

Summary

Weather Forecast

Winds dropped of last night but snow - pushing in from the prairies - continues to fall Saturday with another 5cm expected overnight. The formation of a ridge Sunday should push out a few remaining flurries and usher in some clearing for Monday. Light to moderate winds are expected in the alpine until Tuesday when and increase has been forecast.

Snowpack Summary

50-70 cm has fallen in the past week with strong Westerly winds. Expect to find wind slabs in lee areas and exposed terrain features. The recent snow is piling up and buries sun crust on steep solar aspects and the Feb 1 crust in isolated areas up to 1900m. Generally this area has a strong snowpack, with snow depths over 300 cm in the alpine.

Avalanche Summary

We suspect a limited natural cycle is ongoing. Reports of two deep persistent slab avalanches on Thursday in the alpine of Banff NP on South to East aspects; a sz 3 triggered by cornice fall and a sz 2.5 from explosive avalanche control. A further report of an explosive controlled sz 2.5 on deep persistent layers on Saturday at Sunshine Village.

Confidence

Due to the number of field observations

Problems

Wind Slabs

Expect to find wind & storm slab formation on lee aspects and open areas from the alpine to tree line. 10-15cm of fresh snow may cover these now making them more difficult to detect. Cornices should be considered suspect due to recent growth.

Be careful with wind loaded pockets while approaching and climbing ice routes.
Use caution on steep lee and cross-loaded slopes

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2.5

Loose Dry

Sluffs will fail easily with skier traffic in steep terrain and are failing naturally in very steep terrain. Use caution in gully features or in cliffy terrain where these can have serious consequences.

Good group management is essential to manage current conditions safely.
On steep slopes, pull over periodically or cut into a new line to manage sluffing.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely

Expected Size

1 - 1.5

Valid until: Mar 8th, 2020 5:00PM