Avalanche Forecast

Issued: Apr 15th, 2013 8:00AM

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

danyelle magnan, Parks Canada

Glacier.

Summary

Weather Forecast

Today should be mostly overcast, with cool temps, light flurries and moderate N-NE winds. Overnight a ridge of high pressure will build, bringing mostly sunny skies through Wednesday. As the next frontal system approaches late Wednesday, winds will shift back to W'ly and temperatures and freezing levels will start to rise.

Snowpack Summary

30-50cm of settled storm snow remains dry on north aspects above 1750m. The April 3rd crust is down ~60cm and seems to be bonding in most locations. In isolated areas; protected slopes above 2400m; pockets of surface hoar is buried down ~60cm. Northerly winds have been reverse loading slopes for the past 36 hrs.

Avalanche Summary

Several slab avalanches on large west facing alpine slopes that received the late day sun were observed yesterday evening. A size 2.5 loose avalanche was observed from a south aspect, and 3 size 2 slab avalanches were occurred on north aspects. Skiers reported slow moving sluffs on steep slopes on a north aspect, and moist pinwheels below 1500m.

Confidence

Timing or intensity of solar radiation is uncertain

Problems

Wind Slabs

40-50cm of storm snow is being transported by variable winds. N'ly winds have reverse loaded solar aspects and may bond poorly where buried sun crusts exist. The wind is also building large, unsupported cornices.

Stay off recent wind loaded areas until the slope has had a chance to stabilize.Give cornices a wide berth when travelling on or below ridges.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 3

Loose Dry

Loose snow sluffs can gain mass in steeper terrain catching a rider off guard today. Be mindful of terrain traps (e.g. gullies, cliffs) where small avalanches can be more serious.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Persistent Slabs

Infrequent large avalanches have occurred on deeper instabilities. Shallow, rocky areas where the snowpack is thin and weak are most likely where they will be triggered.

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 surface hoar.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely

Expected Size

2 - 3

Valid until: Apr 16th, 2013 8:00AM