Avalanche Forecast

Issued: Jan 4th, 2019 5:52PM

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

Avalanche Canada shorton, Avalanche Canada

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Heavy snow and wind has left thick storm slabs across the region. The new snow needs more time to heal, so sticking to more conservative terrain is recommended.

Summary

Confidence

Moderate -

Weather Forecast

FRIDAY NIGHT: Cloudy with isolated flurries and localized accumulations of 10 cm, moderate wind from the southwest, alpine temperatures drop to -8 C.SATURDAY: Cloudy with light flurries and possibly a few sunny breaks, moderate wind from the south, alpine high temperatures around -3 C.SUNDAY: 5-10 cm of snow, light wind, alpine high temperatures around -5 C.MONDAY: Mix of sun and cloud, light wind, alpine high temperatures around -10 C.

Avalanche Summary

Observations were limited during the storm, but it's fair to assume that such an intense storm produced a cycle of large natural avalanches over the past few days. As the storm tapers down, human triggering will remain likely.On Friday, there was a report of a snowmobile triggered avalanche at Allan Creek south of Valemount. The avalanche was size 2 (40 cm deep) on an east aspect at 2100 m.Prior to the storm, several small human triggered avalanches were reported in the region, including small slabs (30 cm thick) on buried surface hoar at Sugar Bowl (see this MIN report for details). This layer is now buried much deeper, and at this point it's uncertain whether it could still be reactive.

Snowpack Summary

An intense storm delivered 50-80 cm of snow between Wednesday and Friday. The new snow is rapidly settling at lower elevations, while at higher elevations it continues to get blown around into fresh wind slabs.Prior to the storm, a widespread layer of surface hoar was reactive around treeline elevations. This layer is now 50-100 cm deep, and there is some uncertainty about whether it will still be reactive.Another layer buried 150-200 cm composed of weak facets, surface hoar, and a sun crust is believed to be gaining strength. Places that might still challenge this assumption would be steep north and east facing slopes between 1900-2300 m and steep south-facing slopes in the alpine.The probability of triggering other deep layers in the snowpack is low, but the most suspect areas would be shallow spots in steep rocky terrain.

Problems

Storm Slabs

An icon showing Storm Slabs
An intense storm delivered 40-80 cm of snow and strong wind, leaving storm slabs primed for human triggering. The most suspect areas are steep slopes and lee terrain.
Choose well supported terrain without convexities.Be alert to conditions that change with elevation, especially at higher elevations where wind slabs are more likely.Avoid lingering in runout zones.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1.5 - 3

Valid until: Jan 5th, 2019 2:00PM