Avalanche Forecast

Issued: Feb 23rd, 2014 8:24AM

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

Avalanche Canada rbuhler, Avalanche Canada

Increased hazard for Monday on sun-exposed south facing slopes.See the Forecasters Blog for more information on the 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: Clear and sunny, treeline temperature around -12C, ridgetop winds light NW-NETuesday: Clear and sunny, treeline temperature around -8C, ridgetop winds light variableWednesday: Sunny with increasing cloudiness in the afternoon, treeline temperature around -5C, ridgetop winds light variable

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 Saturday there were several natural size 2 avalanches reported in the region with the deepest releasing 150cm in the snowpack. Neighbouring regions reported natural activity up to size 3.5.Conditions are ideal for human triggering right now and we have received numerous reports of skier triggered avalanches recently, many of which have released quite deep in the snowpack. Several of these avalanches were remotely triggered. On Saturday no new human-triggered avalanches were reported but operations were getting widespread explosive triggered results.  The farthest ran 1.2km and the widest was 200m.

Snowpack Summary

A cohesive slab with an average thickness of 1 m 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 which indicates a high likelihood of large propagations 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 leeward features in wind exposed areas at treeline and in the alpine. In many wind loaded areas, a slab of up to 2 m thickness 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
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 propagations. In wind-loaded areas the slab is 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.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

2 - 6

Wind Slabs

An icon showing 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.
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.>

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

Elevations: Alpine, Treeline.

Likelihood

Likely - Very Likely

Expected Size

1 - 4

Valid until: Feb 24th, 2014 2:00PM