Avalanche Forecast

Issued: Mar 26th, 2013 9:55AM

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

pgoddard, Avalanche Canada

Northwest Coastal.

Summary

Confidence

Fair - Due to variable snowpack conditions

Weather Forecast

Wednesday:Very light snow. Light to moderate SW winds. Alpine temperature near -4.Thursday/Friday: No snow expected. Mainly sunny. Freezing levels around 1500 m by day and dropping by night.

Avalanche Summary

A few naturally-triggered wind slabs and loose moist avalanches have been observed over the last couple of days. Ice fall also triggered size 2.5-3 avalanches near Bear Pass and other areas. On Saturday there was a report of a size 2 avalanche, triggered from a distance by a snowmobile. This slide probably failed on the March 9 surface hoar, which was responsible for a lot of remotely-triggered avalanche activity last week.

Snowpack Summary

Recent new snow is settling with the influence of warm temperatures. Wind slabs may be found at alpine and treeline elevations on many slope aspects due to variable winds. A layer of surface hoar (buried March 9th; now down about 40-60 cm) is slowly becoming less touchy, but professionals are keeping a wary eye on it. In some places this interface is a crust/facet layer. Triggering this layer is becoming a low probability but high consequence problem. Check out the Forecaster's Blog for related discussion. A second surface hoar layer, buried on March 18, is also reported to be gaining strength. The mid snowpack is generally well settled and strong. Cornices are large and untrustworthy, especially when the sun is out.

Problems

Wind Slabs

Watch for wind slabs behind ridges and ribs and in cross-loaded gullies. Cornices are also large and untrustworthy, especially on hot days.

Use ridges or ribs to avoid pockets of wind loaded snow.>Avoid steep slopes below cornices.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 4

Persistent Slabs

A layer of surface hoar buried down 50 cm was especially touchy last week. While the likelihood of triggering is slowly dropping, it can be triggered from a distance, propagate across large distances and create surprisingly large avalanches.

Choose well supported terrain without convexities.>Remote triggering is a concern, watch out for adjacent slopes.>Choose regroup spots that are out of avalanche terrain.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

2 - 7

Valid until: Mar 27th, 2013 2:00PM