Avalanche Forecast

Issued: Feb 21st, 2014 8:25AM

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

rbuhler, Avalanche Canada

Cariboos.

Don't let the improving weather fool you, conditions are very tricky and prime for human-triggered avalanches. The hazard will increase on south facing slopes on the first day of full sun.

Summary

Confidence

Fair - Timing or intensity of solar radiation is uncertain on Sunday

Weather Forecast

Some light disturbance is expected for Saturday as a ridge of high pressure builds. Clear, cold, and dry conditions are expected for Sunday and Monday once the ridge of high pressure has established. Saturday: A mix of sun and cloud, light scattered flurries 0-1cm, treeline temperatures around -10C, ridgetop winds light NWSunday/Monday: Clear and sunny, treeline temperatures around -15C, ridgetop winds light N-NE

Avalanche Summary

Natural avalanche activity is generally decreasing now that the storm has ended but we are still receiving reports of natural activity. 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 Thursday, 1 remotely triggered avalanche was reported in the Cariboos and 8 were reported in the North Columbia Monashees/Selkirks. The skier remote in the Cariboos was triggered from 100m away, released 125cm deep, and was associated with a large settlement.

Snowpack Summary

The recent ten-day storm has produced a cohesive slab that averages 40-80 cm in thickness. This slab 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 200m away which indicates a high likelihood of large propagations within the weak layer. 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

This problem is surprising very experienced professionals and remains primed for human triggering. This meter deep slab has shown a propensity for remote triggering, a phenomenon that should become more prevalent as the slab gains cohesion.

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.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

3 - 6

Storm Slabs

Storm snow is being redistributed as wind slabs on lee terrain features. Primary wind directions have recently been SW through NW. 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.>The new snow will require several days to settle and stabilize.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 4

Valid until: Feb 22nd, 2014 2:00PM