Avalanche Forecast

Issued: Feb 21st, 2014 8:31AM

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.

Avalanche Canada rbuhler, Avalanche Canada

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 and Sunday as a ridge of high pressure builds. Clear, cold, and dry conditions are expected for 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: A mix of sun and cloud, light scattered flurries 0-2cm, treeline temperatures around -15C, ridgetop winds light NWMonday: Clear and sunny, treeline temperatures around -13C, ridgetop winds light NW

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, 2 remotely triggered avalanches and 1 skier controlled avalanche were reported in the Purcells. The largest of these was a size 2.5, the farthest trigger was 75m away, and the deepest was 80cm.  Early reports suggest an avalanche accident involving 1 or more people may have occurred on Friday near Golden.

Snowpack Summary

The recent ten-day storm has produced a cohesive slab that averages 40-90 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

An icon showing 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

An icon showing 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.
Travel on ridgetops to avoid wind slabs on slopes below.>Minimize overhead exposure; avalanches triggered by windloading may reach run out zones.>Avoid freshly wind loaded features.>The new snow will require several days to settle and stabilize.>

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 4

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