Avalanche Forecast

Issued: Feb 10th, 2015 9:07AM

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

Avalanche Canada ghelgeson, Avalanche Canada

Recent snowpack observations have been extremely limited, and the snowpack will likely need more time to adjust to the recent heavy precipitation.

Summary

Confidence

Poor - Due to the number of field observations

Weather Forecast

The big story over the next few days is the increasing freezing level. Wednesday: No precipitation. Freezing level should stay near valley bottom throughout the daylight hours. Winds light and variable at all elevations. Thursday: No precipitation. The freezing level is forecast to rapidly rise to 2500m, topping out around 3000m in the afternoon. Moderate to strong SW winds at treeline, Strong W winds at upper elevations. Friday: No precipitation. Winds light and variable at all elevations. The freezing level should remain around 3000m all day.

Avalanche Summary

Observations have been essentially non-existent in recent days. This likely speaks more to a lack of observers rather than actual conditions. I'm confident recent storm loading has produced large storm slab avalanches at higher elevations, while loose wet or wet slab avalanche activity occurred at lower elevations where rain fell.

Snowpack Summary

Since February 5th, moderate to heavy precipitation fell throughout the region. The rain line during the storms generally hovered around 1700m, although there were periods where rain fell into the alpine. In the alpine, heavy accumulations of moist, dense snow have been pushed by strong southwest winds into much deeper deposits in upper elevation lee terrain. The recent storm snow overlies a hard crust layer (which may have overlying surface hoar) which was formed in late January. At lower elevations, continuous rain has saturated the snowpack. I suspect cornices are large and fragile.In the mid to lower snowpack, you may find the mid-December crust/facet/surface hoar combo. At lower elevations rain has likely destroyed what was left of this layer. At higher elevations recent storm loading may have produced very large avalanches at this interface, although observations have been extremely limited.

Problems

Storm Slabs

An icon showing Storm Slabs
At higher elevations deep and dense storm slabs overlie potentially weak crystals. As you head into the alpine in search of drier snow, be wary of steeper slopes that haven't avalanched as very large avalanches are a concern.
The new snow will require several days to settle and stabilize.>Be alert to conditions that change with elevation.>Be cautious as you transition into wind affected terrain.>Choose conservative lines and watch for clues of instability.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 4

Deep Persistent Slabs

An icon showing Deep Persistent Slabs
A deeply buried week layer which formed in December should still be treated with suspicion. Although not much is known about the current reactivity of this potentially destructive layer, I'd use extra caution in steep, unsupported alpine terrain.
Be aware of the potential for very large, deep avalanches due to the presence of buried surface hoar or a facet/crust layer.>Avoid steep convexities or areas with a thin or variable snowpack.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 5

Valid until: Feb 11th, 2015 2:00PM