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Avalanche Forecast

Archived

Feb 28th, 2014–Mar 1st, 2014

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.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.

Regions

South Columbia.

Although the frequency of natural avalanches has gone down recently, the possibility of triggering a large, destructive avalanche is still very real. See the Forecasters Blog for more insight into this tricky situation.

Confidence

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

Weather Forecast

The ridge of high pressure continues to dominate the forecast. Dry cold arctic air has moved into the region and will remain for the next few days, then towards the end of the weekend, we will see a return to more seasonable temperatures and precipitation.For a more in-depth look at upcoming weather conditions, check out the: WEATHER OUTLOOK Friday night: Clear with a few clouds, freezing level at valley bottom, no precipitation in the forecast, ridge top winds from the north to 20 Km/h. Alpine temperature inversion.Saturday: Sunny, freezing level at valley bottom, ridge top winds from the north around 15 Km/h.Sunday: Sunny, with a few clouds, freezing level at valley bottom, ridge top winds light to 15 Km/h from the SE.Monday: Cloudy with isolated flurries, 5 to 10cm of precipitation, freezing level at valley bottom, light ridge top winds.

Avalanche Summary

Natural avalanches are still occurring in the forecast area. We've also had reports of cornice failures that triggered avalanches.Conditions are ideal for rider triggering right now. We have received numerous reports of skier triggered avalanches, many of which have released quite deep in the snowpack. Several were remotely triggered from a considerable distance and produced large avalanches.

Snowpack Summary

The storm slab about 1.5 metres thick  overlies a persistent weak layer, (surface hoar/facet/crust combo) that was formed during the preceding month of cold dry weather. The storm slab appears to be gaining strength with settlement and warm temperatures but the persistent weak layer beneath it remains widespread at all elevations and aspects. Although this weak layer is not as reactive as it has been, it's still a very real concern. Surface hoar and near surface facetting is occurring on protected/shaded aspects. solar aspects are moist to quite high elevations during the day, with sun crusts forming at night.Large settlements and whumpfs are still being reported indicating the ability of this weak layer to fail and propagate over large distances. Touchy conditions will remain in place for the near future. With the winds changing to north east, wind slab development at tree line may change to south east slopes.In many wind loaded areas, a slab of up to 1.5m thick overlies the persistent weak layer creating ideal conditions for very large avalanches. Weak basal facets exist in some areas, but triggering has now become unlikely.

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.

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.