Avalanche Forecast

Issued: Feb 25th, 2017 4:16PM

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

snow safety, Parks Canada

Banff Yoho Kootenay.

Sporadic natural activity has been seen in the alpine, and human triggered avalanches are still possible at all elevations. We have a structurally weak snowpack and a wide margin of safety is required.

Summary

Weather Forecast

Cloudy skies with light North winds and flurries producing small amounts of snow are forecast for Sunday. Cooler temperatures in the -18 to -20C range are expected in the alpine.

Snowpack Summary

There is 15-25 cm of low density storm snow at tree line with a thin rain-crust below the storm snow at lower elevations. Wind effect on open slopes at tree line and above. Common throughout the region are the weak facets and depth hoar in the lower half of the snowpack, particularly at lower elevations and east of the divide.

Avalanche Summary

Wind triggered sluffing but no new slab avalanches observed on Saturday. Sporadic natural and human triggered avalanches on the weak facets of the lower snowpack continue. Two size 2.5 natural avalanches were observed within the last 48 hours on E-SE aspects in the alpine on Mount Ball and Mount Brett. Both appeared to scrub down to the ground.

Confidence

Due to the number of field observations

Problems

Deep Persistent Slabs

There is a thick slab over a structurally weak snowpack in most areas. Likely areas of triggering are in thin parts of a slope or rocky outcrops at tree line and above. A failure can propagate to deeper areas and cause large avalanches.

Be aware of thin areas that may propogate to deeper instabilites.Use conservative route selection, choose moderate angled and supported terrain with low consequence.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 3

Wind Slabs

Gusty west winds on Saturday have created small wind slabs in the alpine with sluffing in steep gullies.

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

Aspects: North, North East, East.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Feb 26th, 2017 4:00PM