Avalanche Forecast

Issued: Mar 29th, 2014 10:14AM

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

ghelgeson, Avalanche Canada

Northwest Coastal.

Summary

Confidence

Fair - Wind effect is extremely variable

Weather Forecast

Synopsis: A ridge of high pressure over the NWT and little to no flow aloft will lead to a continuation of cold and dry conditions over the North Coast.Sunday: Freezing Level: 700m - 900m; Precipitation: Nil; Wind: Treeline: Light, SE | Ridgetop: Light, NMonday: Freezing Level: 1300 - 1600m; Precipitation: Nil; Wind: Treeline: Light, NW | Ridgetop: Light, NWTuesday: Freezing Level: 1200 - 1700m Precipitation: Nil; Wind: Treeline: Light, SW | Ridgetop: Moderate, NW

Avalanche Summary

Loose snow was sluffing to size 1 on Friday, several sluffs initiated thin size 1 slabs running on an old suncrust. There was a second hand report of a skier triggered size 2 avalanche at treeline that resulted in the skier going for a ride. Sounds like everyone made it out okay, and that the folks involved will head back later in the spring to find their lost gear. If you were part of this incident, we'd love it if you'd fill out a report. Thanks!

Snowpack Summary

Strong Easterly winds have been reported to have caused intense wind transport of the recent storm snow, developing pockets of wind slab on various aspects in the alpine and at treeline. Forecast cool temperatures are not expected to promote much settling or bonding of the near surface layers, and probably not much change to the persistent weak layers. The deeply buried persistent weak layers continue to provide moderate to hard sudden planar results in snow profile tests, but may be deep enough to require a heavy load for triggering. The March weak layer is a combination of hard wind-scoured slab surfaces in exposed terrain, facets and/or surface hoar in sheltered and north aspects, and sun crust on steep solar aspects. This layer is widespread throughout the forecast region and is now buried close to 150cm in most parts of the area. A late January/early February crust/facet/surface hoar combo is now buried 200 cm or more.

Problems

Wind Slabs

Strong Easterly outflow winds have developed hard wind slabs in the alpine and at treeline.

Watch for areas of hard wind slab in steep alpine features.>Use ridges or ribs to avoid pockets of wind loaded snow.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 4

Persistent Slabs

The early March persistent weak layer is buried deep enough to produce large avalanches when triggered. Periods of solar radiation may increase the sensitivity to triggering this buried weak layer.

Avoid areas with overhead hazard.>Avoid runouts where triggering slopes from below is possible.>

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

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 5

Deep Persistent Slabs

The early February persistent weak layer is buried deeply in the snowpack and continues to be a concern. Heavy loads like cornice falls or storm slab avalanches in motion may trigger this weak layer resulting in very large avalanches.

Avoid convexities or areas with a thin or variable snowpack.>Be aware of the potential for large, deep avalanches due to the presence of buried weak layers.>Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

3 - 6

Valid until: Mar 30th, 2014 2:00PM