Avalanche Forecast

Issued: Nov 26th, 2019 4:00PM

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

Avalanche Canada ahanna, Avalanche Canada

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Cold, windy weather is in the forecast for Wednesday. With a recent change in wind direction you may find wind slabs on all aspects.

Summary

Confidence

Moderate - Uncertainty is due to the limited number of field observations.

Weather Forecast

Tuesday Night: Cloudy with isolated flurries bringing trace amounts of snow to eastern parts of the region, wind increasing to 50 km/h from the northeast, alpine temperatures dropping to -12 C.

Wednesday: Mostly cloudy with isolated flurries bringing trace amounts of snow to eastern parts of the region, 50-70 km/h wind from the northeast, alpine temperatures dropping to -17 C.

Thursday: Sky clearing through the day, wind easing to 20-30 km/h from the northeast, alpine temperatures around -15 C.

Friday: Clear skies, light wind from the northeast, alpine temperatures rising to -10 C.

Avalanche Summary

The most likely place for avalanches to be triggered right now is on slopes where the wind has blown surface snow into wind slabs. A MIN report from the weekend shows the type of terrain where triggering thin wind slabs is a concern. This group of skiers reported a 20 cm thick slab that was triggered on north-facing slope at 2100 m. Observations are limited this time of year, so there is a fair bit of uncertainty about the extent of current avalanche activity.

Snowpack Summary

A recent change in wind direction from southwest to northeast is expected redistribute surface snow, resulting in wind slabs on all aspects. Beneath this, the snow pack consists of various crusts and a potential feathery, weak surface hoar layer 50 cm below the surface (see video here). With few field observations, uncertainty remains on the distribution and reactivity of these layers. It's still early season and the snow pack remains fairly thin. At the deepest, up to 100 cm can be found on north aspects in the alpine.

Problems

Wind Slabs

An icon showing Wind Slabs

Avalanches are most likely to be triggered at higher elevations where wind has blown the snow into wind slabs. With the recent reversal in wind direction, these wind slabs may be found on all aspects.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

1 - 1.5

Valid until: Nov 27th, 2019 5:00PM

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