Avalanche Forecast

Issued: Feb 24th, 2014 8:36AM

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.

The hazard may increase with rising temperatures and solar warming on South aspects. See the forecasters blog for more information on current tricky conditions.

Summary

Confidence

Fair - Timing or intensity of solar radiation is uncertain

Weather Forecast

A strong arctic ridge of high pressure dominates conditions for the forecast period. Clear and dry conditions are expected for the next three days with a bit of a warming trend.Monday night: Clear and cold, treeline temperature around -10C, ridgetop winds light NETuesday: Clear and sunny, treeline temperature around -7C, ridgetop winds light variableWednesday: Clear and sunny, treeline temperature around -6, possiblility of an alpine temperature inversion - ridgetop winds light variableThursday: Sunny with some cloudy periods, possible flurries, light ridge top winds.

Avalanche Summary

We have been receiving less reports of natural activity in the last couple days, but the natural avalanches that are occurring have been increasing in size. On Sunday there were several natural size 2 avalanches reported in the region.Conditions are ideal for human triggering right now and we have received numerous reports of skier triggered avalanches, many of which have released quite deep in the snowpack. Several of these avalanches were remotely triggered. On Sunday we received two reports of remotely triggered avalanches in the South Columbias. The largest of these were size 2, the deepest was 120cm, and the farthest remote trigger was 100m away.

Snowpack Summary

A cohesive slab with an average thickness of 1m sits on a nasty persistent weak layer (surface hoar/facet/crust combo) that was formed during the preceding month of cold, dry weather. This weak layer is widespread at all elevations and aspects, and is creating problems even in previously skied terrain. Large settlements and whumpfs have been reported at all elevations. We have received numerous reports of remotely-triggered avalanches from as far as 500m away, indicating a high likelihood of large propagation within the weak layer. Touchy conditions are expected 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 lee features in wind exposed areas at treeline and above. In many wind loaded areas, a slab of up to 2 m thickness overlie the persistent weak layer creating conditions for very large avalanches.For the most part, the mid and lower snowpack are strong and well consolidated.

Problems

Persistent Slabs

A thick slab from the last series of storms sits on top of a touchy persistent weak layer. This slab has shown a propensity for remote triggering and large propagation. In wind-loaded areas the slab is up to 2m thick.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>Use very conservative route selection, stick to simple well supported terrain that is low consequence and free of overhead hazard.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

2 - 6

Wind Slabs

Previous storm winds 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.

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

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

Elevations: Alpine, Treeline.

Likelihood

Likely - Very Likely

Expected Size

1 - 4

Valid until: Feb 25th, 2014 2:00PM