Avalanche Forecast

Archived

Apr 4th, 2014–Apr 5th, 2014

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches possible, human triggered probable.

Regions

Kootenay Boundary.

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Confidence

Fair - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

Overnight and Saturday: Freezing level dropping briefly below 1500 metres and then rising up to 1800 metres in the afternoon. Southwest winds becoming strong in the afternoon as moderate precipitation begins to fall.Sunday: 5-10 cm is expected by morning before the ridge of high pressure moves into the region bringing broken skies and freezing levels rising to 2000 metres. Winds becoming strong Westerly.Monday: Freezing level remaining above 2000 metres overnight and rising up to 2500 metres. Broken skies with periods of strong solar radiation.

Avalanche Summary

No new avalanches reported.

Snowpack Summary

There is 5-10 cm of new snow that developed a new storm slab. The new thin storm slab is sitting on a 2-5 cm melt-freeze crust that developed over the past few days on all but shaded North aspects in the alpine. This crust has been reported to be "knife" resistance in some parts of the region and may have a layer of surface hoar below the new storm snow. There is now about 75 cm of well compacted snow above the March 10th melt-freeze crust. In some areas the March 10th crust is helping to bridge over the deeply buried late January/early February persistent weak layer. The Jan/Feb deep persistent weak layer continues to be a concern for very large destructive avalanches. Releases on this layer may be more likely during periods of strong solar radiation and/or prolonged warm temperatures at alpine elevations.

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.