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Large persistent slab avalanches

Observed Apr 21, 2025, 10:00 a.m. PDT · Yukon

This report was submitted with an older form.

Wide propagation on upper crown lineTwo separate slides with older crown lines in the same area.ECTP21 down 45cm at 1600m on a NW-aspect. Failure layer of faceted snow crystals. Slick skin track with compacted surface hoar. Widespread surface hoar.Cornice failure. Recent natural activity on an E-aspect.

Quick report

Comment
Large natural persistent slab avalanches in the Rainy hollow area on NW-aspects at 1500m with spectacular propagation ~750m. And a deep slab lower on a moraine feature at 1100m. Observed cornice fall and other slab avalanches on Northerly aspects. Dug a pit at 1600m on a NW-aspect and found a reactive slab down 45cm that propagated on extended column test ECTP21. It failed on faceted snow below a crust layer. Overall poor structure below this interface with punchy layers and strong over weak layering. At the surface on the northerly was a layer of surface hoar over a firm supportable surface. Big cornices and evidence of recent cornice failure.
Weather
Sunny
Ride type
Alpine slopes, Mellow slopes, Sunny slopes
Stayed away
Convex slopes, Steep slopes
Riding quality
Good
Snow conditions
Crusty, Powder
Avalanche conditions
Avalanche condition sound