Avalanche Forecast

Issued: Feb 17th, 2016 9:07AM

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

rbuhler, Avalanche Canada

Northwest Inland.

Recently formed storm and wind slabs will continue to be reactive to human-triggering on Thursday and conservative terrain selection remain critical.Use extra caution on south facing slopes in the afternoon if the sun is out in full force.

Summary

Confidence

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

Weather Forecast

3-10cm of snowfall is expected Wednesday overnight throughout most of the region. On Thursday, most of the region should see dry conditions with a mix of sun and cloud. Freezing levels are expected to be around 1000m and should fall to valley bottom overnight. Alpine winds are forecast to be light from the west. Friday is expected be mainly dry and cloudy but light flurries and sunny breaks are both possible. Afternoon freezing levels are expected to reach 700-900m and alpine winds should be light from the southeast. The next organized storm system is forecast to hit the north coast Friday night and 5- 15cm is currently being forecast to reach the inland region.

Avalanche Summary

On Tuesday, a size 1 storm slab was ski cut on a convex roll at treeline. On Monday, isolated wind slab avalanches up to size 1.5 were reported. On Sunday, a ski cut produced a size 1 storm slab avalanche on an east aspect at 1400m elevation. The slab was 25cm thick. A small natural cycle was reported on Sunday up to size 2 and failing in the recent storm snow, mainly in the alpine. Recently formed storm and wind slabs are expected to remain reactive to human-triggering on Thursday. If the sun comes out, natural avalanches are possible on steep south facing terrain features. In the far north, deeply buried persistent weak layers may still be reactive to large triggers such as a small avalanche stepping down or a cornice failure.

Snowpack Summary

40-80cm of snow has accumulated over the past week and overlies a melt freeze crust which extends up to around 2000m elevation. This recent snow is reported to be bonding well to the crust. Moist snow was reported below 1100m on Tuesday and wet snow below 800m. Recent wind has redistributed the surface snow at higher elevations forming wind slabs in leeward features. The early January surface hoar/facet layer is down around 1m+ and remains a concern for commercial operations. This layer seems the most reactive in the north of the region but may still be a concern in the south as well. Shallow snowpack areas in the east and north of the region may have a weak base layer of facetted snow on or just above the ground.

Problems

Storm Slabs

Recently formed storm slabs are expected to be very sensitive to human-triggering on Thursday. Wind loaded features are likely to have the most reactive slabs.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>The new snow will require several days to settle and stabilize.>Avoid freshly wind loaded features.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Deep Persistent Slabs

Buried weak layers are still reactive in the snowpack, especially in the far north of region, and have the potential to produce very large avalanches. Thin spot triggering, cornice releases, and smaller avalanches all have the potential to step down.

Be aware of the potential for large, widely propagating avalanches due to the presence of buried surface hoar.>Avoid convexities or areas with a thin or variable snowpack.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 6

Valid until: Feb 18th, 2016 2:00PM