Avalanche Forecast

Issued: Dec 18th, 2018 4:49PM

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

Avalanche Canada shorton, Avalanche Canada

We're lacking information about recent avalanche activity, so it's critical to make your own observations. Back off if you see recent avalanches, cracking, or whumpfing.

Summary

Confidence

Low - Due to the number of field observations

Weather Forecast

TUESDAY NIGHT: Flurries with localized accumulations of 3-8 cm, strong wind from the southwest, freezing level dropping to valley bottom, alpine temperatures drop to -8 C.WEDNESDAY: Mostly cloudy with isolated flurries, moderate wind from the southwest, alpine temperatures steady around -8 C.THURSDAY: Scattered flurries with up to 5 cm of snow, light to moderate wind, alpine high temperatures around -8 C.FRIDAY: Mostly cloudy with isolated flurries, moderate wind from the west, alpine high temperatures around -8 C.

Avalanche Summary

On Sunday, recent slab avalanches, whumpfing, and cracking were observed in the Hankin area. See this MIN report. Natural slab avalanches were also reported last week during the start of the stormy weather, including two large avalanches (size 2) on east-facing wind-loaded slopes near treeline (1700 m) and several smaller slabs in steep gullies at low elevations. See this MIN report from Ashman. Recent avalanches have probably failed in the storm snow and possibly on a weak layer from the early December dry spell found roughly 40-70 cm below the surface.

Snowpack Summary

A total of 40-70 cm of snow has fallen over the past week, likely forming storm slabs and wind slabs throughout the region. The combination of new snow and strong wind from the southwest is likely forming thicker and more sensitive wind deposits at higher elevations. The storm snow may still need a bit more time to form a good bond with the weak surface hoar and facets that formed during the dry spell in early December. We're lacking information about the current strength of this potential weak layer. Deeper in the snowpack, there are several crusts including an early season crust with facets near the bottom of the snowpack.

Problems

Wind Slabs

An icon showing Wind Slabs
40-70 cm of new snow from the past week has the potential to form reactive slabs. Wind loaded slopes at higher elevations are the most suspect for human triggering.
Field observations have been limited. Supplement this forecast with your own observations.Be alert to conditions that change with elevation, aspect, and exposure to wind.Approach steep lee and cross-loaded slopes with caution.

Aspects: North, North East, East, South East, North West.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Dec 19th, 2018 2:00PM