Avalanche Forecast

Issued: Feb 27th, 2014 8:18AM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is considerable. Known problems include Persistent Slabs and Wind Slabs.

bcorrigan, Avalanche Canada

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.

Summary

Confidence

Fair - Timing or intensity of solar radiation is uncertain

Weather Forecast

The ridge of high pressure continues. Dry, even colder arctic air forecast to move back into the region by this weekend. For a more in-depth look at the weather, check out the latest: WEATHER OUTLOOK Thursday night: Cloudy periods, freezing level at valley bottom, ridge top winds, light to 25Km/h.Friday: Sunny, freezing level at valley bottom, no precipitation in the forecast, ridge top winds from the north to 20 Km/hSaturday: Sunny, freezing level at valley bottom, ridge top winds from the north gusting to 40 Km/h.Sunday: Sunny, freezing level at valley bottom, ridge top winds light.

Avalanche Summary

Natural avalanches are still occurring up to size 3 in the forecast area, and as temperatures warm up may increase in frequency. We've had one report of a cornice failure that triggered an avalanche.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 of about 1 metre 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

A thick storm slab from the last series of storms now lies above a touchy, persistent weak layer. This slab has shown a propensity for remote triggering and propagating over wide distances. In wind-loaded areas the slab may be up to 1 1/2 m. thick.

Avoid slopes with glide cracks.>Use very conservative route selection, stick to simple well supported terrain that is low consequence and free of overhead hazard.>Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>The new snow will require several days to settle and stabilize.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 5

Wind Slabs

Wind slabs development may now switch to south and south west slopes as the incoming arctic air drives down from the north east. This may build cornices in places not usually seen.

Do not travel on slopes that are exposed to cornices overhead.>Travel on ridgetops to avoid wind slabs on slopes below.>Avoid freshly wind loaded features.>

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 4

Valid until: Feb 28th, 2014 2:00PM