Avalanche Forecast

Issued: Feb 27th, 2014 8:12AM

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

Cariboos.

Riders should remain vigilant for changing conditions. Terrain choices are critical as this snowpack evolves. Check out the latest: Forecasters Blog

Summary

Confidence

Fair - Freezing levels are uncertain

Weather Forecast

The ridge of high pressure continues to dictate conditions for the forecast period. Dry cold arctic air scheduled to move back into the region. Strong arctic outflow winds have already begun and will continue into the coming weekend. For a more in-depth look at upcoming weather conditions, check out the: 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

Reports of avalanche activity in the forecast region include cornice failures, skier accidentals, and skier controlled avalanches. Solar warming on steep south aspects may trigger avalanches that might "step down" to weak mid -pack and basal layers possibly triggering a very large slide. Conditions are ideal for rider triggering right now. Skiers and riders need to be mindful that although the frequency of natural avalanches has gone down recently, the consequences of triggering a large avalanche could be devastating.

Snowpack Summary

The storm slab (surface hoar/facet/crust combo) that was formed following the preceding month of cold, dry weather appears to be gaining strength with settlement and warm temperatures. The persistent weak layer remains widespread at all elevations and aspects, and although it is not as reactive as it has been, it's still a very real concern. Large settlements and whumpfs are still being reported. Remotely-triggered avalanches indicate the ability of this weak layer to fail and propagate over large distances. Touchy conditions are expected to remain in place longer than we're normally accustomed to. Some Katabatic (down-flowing) winds slab formation is being reported as well.In many wind loaded areas, a slab of up to 2m thick overlies the persistent weak layer creating conditions for very large avalanches. Winds changing to NE in the coming days may build wind slabs on SW and S slopes.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

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 2m thick.

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

Previous storm winds have created wind slabs on lee terrain features. The primary wind direction was SW but we also had some NW winds. Weak cornices are also a concern and have the potential to trigger large avalanches on the slopes below.

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

Likely

Expected Size

1 - 4

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