Avalanche Forecast

Issued: Apr 1st, 2018 4:38PM

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

Avalanche Canada cgarritty, Avalanche Canada

Maintain conservative terrain selection as we transition out of the storm. Watch for periods of sun to destabilize sun-exposed slopes.

Summary

Confidence

Moderate - Timing or intensity of solar radiation is uncertain

Weather Forecast

Monday: A mix of sun and cloud. Light southeast winds. Alpine high temperatures around -11.Tuesday: A mix of sun and cloud. Light southwest winds. Alpine high temperatures around -10.Wednesday: Cloudy with light flurries beginning in the afternoon and continuing overnight. Light southeast winds. Alpine high temperatures around -6.

Avalanche Summary

Reports from Saturday included two more natural slab avalanches. A size 1.5 storm slab failed on a south aspect at 2300 metres while another deeper size 2.5 slab released from a very steep north aspect at 2700 metres. Their respective crown fracture depths were 80 cm and 200 cm and the failure plane of the deeper release is not certain.On Friday, a natural size 2.5 storm slab avalanche was reported west of Valemount on a northwest aspect at 2400 m.On Thursday, a few size 2 natural storm slab avalanches were reported on north and east aspects. A cornice fall triggered a large slab avalanche with a 100 cm crown on a north aspect at 2600 m. A skier also remotely triggered a size 1 wind slab on a southeast aspect at 1900 m.These avalanches follow a widespread natural avalanche cycle that occurred on Tuesday and Wednesday. Storm slabs in the size 2-3 range were reported on all aspects between 1700 and 2500 m. Southerly aspects were the most reactive with numerous large and very large (size 2.5-3.5) avalanches running on the recently buried sun crust.

Snowpack Summary

Another 20-30 cm of new snow on Friday brought last week's total to 60-100 cm. Storm snow was accompanied with strong west wind, forming reactive slabs at higher elevations.The storm snow sits on an interface buried in late-March that consist of crusts at low elevations and on south aspects, and surface hoar on shaded aspects at higher elevations.Persistent weak layers from early January and mid-December are still being reported by local operators, but are generally considered dormant.

Problems

Storm Slabs

An icon showing Storm Slabs
Human-triggered storm slabs remain a concern on wind-affected features and on south aspects where they sit above buried sun crusts. Periods of sunshine may also undermine stability on sun-exposed slopes.
Avoid freshly wind loaded features.Choose well supported terrain without convexities.Minimize exposure to steep planar south-facing slopes - especially if they see sunshine.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2.5

Valid until: Apr 2nd, 2018 2:00PM

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