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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 unlikely, human triggered possible.

Regions

South Coast.

What's going to happen to the snowpack if it warms up significantly on Sunday/Monday/Tuesday? Read a discussion here...

Confidence

Fair - Timing or intensity of solar radiation is uncertain on Sunday

Weather Forecast

Synopsis: Moderate precipitation expected on Saturday before a ridge of high pressure builds for Sunday and Monday. Saturday: 5-10 cm new snow expected with freezing levels around 1200 m. Winds 40-50 km/h from the SW. Sunday: Scattered showers in the morning, becoming dry in the afternoon with some sunny breaks. Freezing levels around 1200 m. Winds 20-30 km/h from the NW. Monday: Dry. Sunny in the morning, becoming more cloudy in the afternoon. Warm, with freezing levels rising to 2200 m.

Avalanche Summary

Minor sluffing was reported from the Duffey Lake area on Thursday, but no slab avalanche activity was noted. I suspect some relatively small storm slab avalanches occurred Friday in response to the new snow and loading from wind. On Wednesday, a cornice fall on a steep north facing features at 2300m initiated a size 3 avalanche. It likely ran on the early March melt-freeze crust.

Snowpack Summary

5-10 new snow sits above a mix of surface hoar, small grained facets and melt freeze crusts.Recent warm temperatures have helped to settle and strengthen the upper snowpack. Down 30 - 50 cm below the surface, snowpack tests are still producing hard resistant planar shears on the late March crust.The persistent weak layers from early March and early February continue to be a concern. The March melt-freeze crust/surface hoar is reported to be down 60 - 100cm. The February crust/facet/surface hoar layer is now deeply buried down 150 - 250cm.The lower snowpack is strong and well settled.

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.