Avalanche Forecast
Issued: Feb 25th, 2019 4:16PM
The alpine rating is Persistent Slabs and Storm Slabs.
, the treeline rating is , and the below treeline rating is Known problems includeKeep using conservative terrain selection to reduce your exposure to recent storm slabs as well as our lingering persistent slab problem.
Summary
Confidence
High -
Weather Forecast
Monday night: Clear. Light northeast winds.Tuesday: Sunny. Light northeast winds, increasing over the day. Alpine high temperatures around -10.Wednesday: Mainly cloudy. Light southeast winds. Alpine high temperatures around -7.Thursday: A mix of sun and cloud. Light variable winds. Alpine high temperatures around -7.
Avalanche Summary
Several small (size 1) human triggered slabs were reported in the storm snow on Saturday and Friday. Loose dry sluffing was also observed in steep terrain.Persistent slab avalanches on the buried crust layer are still a serious concern. One occurred naturally on a south-facing feature at treeline elevation on Wendesday (see MIN report here). Last Monday, a fatal avalanche occurred on a steep feature at treeline elevation in the Mount Seymour backcountry (see here for incident report). Avalanche professionals involved in the rescue indicated wide propagation consistent with a persistent slab problem. The crown depth was variable - 40 to 100 cm, indicating there was also wind loading in that area.
Snowpack Summary
Roughly 30 cm of snow from the weekend storm sits above a mix of sun crusts and possibly some weak faceted snow and surface hoar. Below this gradually strengthening interface, a widespread crust layer is now buried 50-100 cm deep with weak snow above it. This deeper weak layer has produced large natural and human-triggered avalanches over the past week. A couple of videos from last Wednesday demonstrate how easy it is to trigger this layer. (see here and here)The reactivity of this layer appears to be worse in the south of the region (i.e. the North Shore Mountains), since this part of the region saw more snow from recent storms and this storm snow consolidated into a stiffer slab. This problem is not typical for the region and we expect this layer to remain reactive for some time into the future. The lower snowpack is settled and strong.
Problems
Persistent Slabs
A weak layer of facets over a crust is buried 50-100 cm deep. Triggering large avalanches on this layer remains possible in steep terrain.
Be aware of the potential for wide propagations due to the presence of a buried weak layer.Minimize exposure to sun exposed slopes when the solar radiation is strong.Use conservative route selection, choose moderate angled and supported terrain with low consequence.
Aspects: All aspects.
Elevations: Treeline, Below Treeline.
Likelihood
Expected Size
Storm Slabs
Storm slabs may remain sensitive to human triggering in steep terrain. 30 cm of recent snow may be poorly bonded to the snow below.
Use caution above cliffs where small avalanches may have severe consequences.Choose well supported terrain without convexities.If triggered the storm slabs may step down to deeper layers resulting in large avalanches.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Feb 26th, 2019 2:00PM