Avalanche Forecast

Issued: Nov 26th, 2019 4:00PM

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

Avalanche Canada astclair, Avalanche Canada

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Winds change direction and increase in intensity.

With a complex wind-loading pattern in an unconventional early season, it will be important to remain cautious, use small terrain features, and gather information where you are travelling.

Summary

Confidence

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

Weather Forecast

Clear, cold, and dry weather moves in for the week with strong east/northeast winds.

Tuesday night: Scattered clouds, alpine temperature -18 C, moderate to strong east/northeast winds, no significant precipitation expected.

Wednesday: Clear skies, alpine temperature -15 C, strong east/northeast winds, no significant precipitation expected. 

Thursday: Clear skies, alpine temperature -18 C, light east wind, no significant precipitation expected. 

Friday: Clear skies, alpine temperature -15 C, light east wind, no significant precipitation expected.

Avalanche Summary

Observations are lean right now, but the recent snow combined with wind is expected to form wind slabs with the potential for human triggering. This MIN post has a great photo that is pretty representative of what we're envisioning. If you've been out recently, please let us know what you're seeing on the Mountain Information Network. We're particularly interested in learning how widespread and sensitive the wind slab problem is. Thanks!

Snowpack Summary

Winter is slowly descending into the valleys with the snowline around 1200 m across the region. Total snowpack depths range from about 80 cm below treeline to as high as 180 cm in the alpine.

The weekend storm produced 20 to 35 cm of snow, which is likely to be redistributed into stiff slabs by strong northeast winds on Wednesday. On steep south facing slopes in the alpine, the new snow rests on a crust. A crust is also present on all aspects below 1600 m, and many locations have surface hoar (feathery crystals) on top of the crust. 

Crusts that formed in late October are now buried 50 to 100 cm deep. We're working off of a short list of observations, but this late October crust layer is highly variable and may be associated with both surface hoar and facets. This is a layer to watch over the next week as unlimited visibility and good travel conditions begin to sing the Alpine's siren song.

Problems

Wind Slabs

An icon showing Wind Slabs

Winds are expected to increase in intensity and shift to the east/northeast. These winds are likely to redistribute the weekend's 20-30 cm of snow into slabs over the previously wind-affected surfaces in the alpine and the crust and surface hoar combination that formed near tree line. 

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2.5

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