Avalanche Forecast

Issued: Apr 2nd, 2015 9:27AM

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

ccampbell, Avalanche Canada

Northwest Coastal.

A weak surface hoar layer is creating touchy conditions in some areas. If you have field observations to share, please consider using the Mountain Information Network. Click here for more info.

Summary

Confidence

Good

Weather Forecast

5-15 cm of snow is expected overnight Thursday and throughout the day Friday with another 5 cm each day on Saturday and Sunday. Daytime high freezing levels are expected to hover around 1300 m for Friday and Saturday and a bit higher on Sunday. Alpine winds are expected to pick up to moderate to strong southwesterlies on Thursday night, but gradually ease off throughout the weekend.

Avalanche Summary

Reports from Wednesday include several explosive-controlled wind slab avalanches up to Size 2.5 running on facets buried March 25th. A remotely triggered Size 2.5 avalanche released above two skiers catching both of them and burying one, who was successfully recovered. This avalanche failed on the same March 25th weakness, where it was buried surface hoar on a northeast aspect at 1450 m.

Snowpack Summary

Around 50-70 cm of recent settled storm snow is bonding poorly to a variety of old snow surfaces including surface hoar and facets buried on March 25th. This weakness is very touchy with a high propensity for propagating fractures, especially where buried surface hoar is the culprit. This is certainly the case in the northern parts of the region, but given the seriousness of the problem it's best to dig down and investigate for yourself if you are uncertain. Weaknesses have also been found within the recent storm snow with snowpack tests producing moderate sudden results down approximately 30 and 40 cm. The early March facet/crust persistent weakness is now down around a metre and unreactive with snowpack tests.

Problems

Persistent Slabs

Remote triggering and widespread propagations makes surface hoar buried last week particularly tricky to manage. Uncertain distribution across the region requires a cautious approach until you are certain that buried surface hoar isn't lurking.

Choose conservative lines and watch for clues of instability.>Be aware of the potential for large avalanches due to the presence of buried surface hoar.>Dig down to find and test weak layers before committing to a line.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 4

Storm Slabs

Recently formed storm slabs should gradually gain strength over the next few days. That said, large avalanches are still possible in in higher elevation, wind-exposed terrain.

Be alert to conditions that change with aspect and elevation.>Stay off recent wind loaded areas until the slope has had a chance to stabilize.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Apr 3rd, 2015 2:00PM