Avalanche Forecast

Issued: Feb 24th, 2016 8:34AM

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

pgoddard, Avalanche Canada

Northwest Coastal.

Weather models are having a hard time pinning down the details of the incoming storm. Snow, wind, rain and rising temperatures are all possible, and will increase the avalanche danger.

Summary

Confidence

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

Weather Forecast

The Jet stream clips the NW coastal region, while directing the most intense precipitation north of the area. On Thursday and overnight, 5-15 mm precipitation is expected with the freezing level climbing towards 2000 m on Thursday afternoon. Winds become strong from the south. Light snow is expected on Friday, with winds easing to moderate south-westerlies. There is a lull in the weather forecast for Friday night/ Saturday.

Avalanche Summary

A handful of size 1-2 loose wet avalanches failed yesterday on steep solar aspects. Skiers have also triggered a few small wind slabs over the last couple of days. Northeast of Bell 2, a natural avalanche at treeline was observed to have stepped down to the early January surface hoar on Sunday. While this avalanche technically occurred in the Northwest Inland region, it is a good reminder that this layer remains a concern, especially in thin snowpack areas.

Snowpack Summary

Recent strong winds have created wind slabs on a variety of slopes at alpine and treeline elevations. Some solar aspects have a thin sun crust at the surface. In some spots sheltered from the wind and sun, surface hoar has survived. Incoming snow may bond poorly to these surfaces. 40-100 cm of snow sits above a melt freeze crust buried around February 12th. This crust extends up to about 2000 m. Although the snow above is bonding well to this crust in most places, recent snow pit tests northwest of Terrace produced failures on or in facets just below this layer under moderate to hard loads. Below this, a layer of surface hoar buried late in January remains a concern in thin snowpack areas in the east and north of the region. The snowpack in these areas may also sit on a weak base of facets near the ground.

Problems

Storm Slabs

Incoming snow, wind and rising temperatures may create a new storm slab problem. Recently formed wind slabs are also lurking on many alpine and treeline slopes.

Be alert to conditions that change with aspect and elevation. >Choose conservative lines and watch for clues of instability.>Choose well supported terrain without convexities.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Loose Wet

Rising freezing levels may bring rain and lead to loose wet avalanches. These can gather a lot of mass and push you around.

Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Persistent Slabs

A storm slab or wet avalanche could step down and trigger a deeply buried weak layer, creating a surprisingly large avalanche.

Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar. >Dig down to find and test weak layers before committing to a big line. >

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 6

Valid until: Feb 25th, 2016 2:00PM