Avalanche Forecast

Archived

Feb 20th, 2014–Feb 21st, 2014

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches possible, human triggered probable.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches possible, human triggered probable.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches possible, human triggered probable.

Regions

Cariboos.

We're moving from a storm slab problem to a persistent slab problem. Check out this blog post for thoughts on the current situation and strategies for the next the chapter.

Confidence

Fair

Weather Forecast

Unsettled conditions are expected for the next three days as the stormy conditions end and a ridge of high pressure begins to build. A very weak system from the coast may affect the interior regions on Sunday. Friday: Cloudy with sunny breaks, scattered flurries 1-3cm, treeline temperatures around -10C, ridgetop winds 30-40km/h NW easing in the afternoonSaturday: A mix of sun and cloud, mainly dry conditions, treeline temperatures around -12C, ridgetop winds light variableSunday: A mix of sun and cloud, scattered flurries possible 0-2cm, treeline temperatures around -18C, ridgetop winds light variable

Avalanche Summary

Widespread natural avalanche activity up to size 2.5 was reported on Wednesday. The common theme is deep releases with around half of the reported avalanches having a slab thickness of 100-150cm. The majority of the avalanche activity is still failing on the early-Feb weak layer.From limited reports, natural activity appears to have reduced substantially on Thursday. One size 1 skier remote was reported with triggering occurring 100m away and a large settlement felt.

Snowpack Summary

The never ending storm cycle has produced 80-160 cm of total snowfall across the region which is settling into a cohesive slab that averages 45-80 cm in thickness. This slab sits on a nasty persistent weak layer surface hoar/facet/crust combo that was formed during the month of cold dry weather. Field observers continue to report easily triggered sudden planar failures on this interface in snowpack tests. Large settlements and whumpfs have been reported at all elevations, even in previously skied terrain. Large natural avalanches have been widespread and destructive. We expect touchy conditions to remain in place longer than we're normally accustomed to. Recent strong winds out of the SW through NW have created wind slabs on leeward features in wind exposed areas at treeline and in the alpine. In many areas, thick wind slabs may overlie the persistent weak layer creating conditions for very large avalanches.Weak basal facets exist in some areas, but triggering has now become unlikely. For the most part, the mid and lower snowpack are strong and well consolidated

Problems

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.

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.