Avalanche Forecast

Issued: Apr 12th, 2015 8:55AM

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

bcorrigan, Avalanche Canada

Sea To Sky.

Use caution in areas with recent wind deposition

Summary

Confidence

Fair - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

Unsettled weather in the wake of the last frontal system that passed through the area yesterday.MONDAY: Cloudy with flurries,10 to 15cm of snow, freezing level around 1200m, and winds moderate from the South.TUESDAY: A break in the weather, cloudy with sunny periods, freezing level may go to 1200m, wind from the South West.WEDNESDAY: Cloudy with flurries, possible 5cm accumulation through the day. Freezing level around 1300m and beginning to climb for the remainder of the week. winds light to moderate from the South.

Avalanche Summary

Explosive control yesterday produced numerous 1 to 1.5 soft slab avalanches. Commercial operators are noting soft slabs in lee terrain. Not many observations reported, mostly as a result of poor visibility during the storm cycle. We expect wind slab activity and cornice failures with the current weather pattern and increased loading, as well as loose-wet avalanches on solar aspects when the sun comes out.

Snowpack Summary

Up to 25cm of recent precipitation on a variety of crusts and old surfaces. Surface hoar and facets may remain in some sheltered locations from the recent clear weather. Moderate to strong south west winds have redistributed the storm snow into wind slabs on the lee sides of ridge tops. A facet/crust layer buried in mid-March has been producing hard and sudden results in snowpack tests. This remains a concern in the region due to it's potential to produce very large avalanches. Cornices are also a concern these days. A cornice failure may trigger a large destructive avalanche. Convective flurries can quickly deposit relatively large amounts of precipitation in a short period with spring weather.

Problems

Wind Slabs

Strong winds with the recent storms have built soft slabs on lee terrain features. These could propagate large enough to injure or bury a skier / rider.

Avoid freshly wind loaded features.>Highmark or enter your line well below ridge crests to avoid wind loaded pillows.>Stay off recent wind loaded areas until the slope has had a chance to stabilize.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 4

Persistent Slabs

Very little activity on this layer recently, but it's still worth considering the possibility of activating this persistent problem. It could produce a large and destructive avalanche if triggered.

Avoid convexities or areas with a thin or variable snowpack.>Be aware of the potential for large, deep avalanches due to the presence of a buried crust/facet layer.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 5

Valid until: Apr 13th, 2015 2:00PM