Avalanche Forecast

Issued: Nov 13th, 2015 8:23AM

The alpine rating is high, the treeline rating is considerable, and the below treeline rating is moderate. Known problems include Storm Slabs, Wind Slabs and Loose Dry.

danyelle magnan, Parks Canada

Glacier.

It's dumping and blowing and overloading a weak surface hoar layer. Avalanches are expected today and will likely run full path. Avoid exposure to avalanche terrain, including crossing paths that are still filled with alder in the valley bottom!

Summary

Weather Forecast

The storm parked over us will bring up to another 20cm today, with strong SW ridge-top winds. Fortunately freezing levels should stay below 1600m. The next pulse is expected to arrive later on Saturday bringing up to another 50cm, with strong alpine winds and freezing levels around 1600m. Wet, windy and warm; perfect for a natural avalanche cycle!

Snowpack Summary

~50 of storm snow now sits on the widespread Remembrance Day surface hoar layer. With continued loading it is forming a slab. Test results indicate the surface hoar is easily triggerable, and as the slab develops it is capable of producing large avalanches. SW winds are adding to the slab properties in lee features at alpine and tree-line.

Avalanche Summary

By yesterday afternoon the snow over the Nov 11 surface hoar layer was forming a soft slab. Skiers reported cracking and small skier triggered slabs. Recent natural avalanches have been occurring from steep, alpine terrain but running into the alder in the avalanche run-outs. The size 3.5 avalanche off of Bruins Ridge on Sunday opened many eyes.

Confidence

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

Problems

Storm Slabs

All this new snow is forming a soft slab sitting on a reactive surface hoar layer. As the slab develops, and with ongoing loading by the new snow and wind, both natural and skier triggered avalanches are likely.

Watch for whumpfing, hollow sounds, and shooting cracks.Minimize overhead exposure during periods of heavy loading from new snow, wind.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Wind Slabs

Southerly winds at ridgetop have been at the perfect speed for windloading over the past few days. With lots of low density snow available for transport expect soft windslabs and fat loaded pillows on lee features.

Be aware of the potential for wide propagations.Use caution in lee areas. Recent wind loading have created wind slabs.

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Loose Dry

Be careful in gullies features where your sluff will be concentrated and may be deep enough to knock you over or bury you. In addition, even a small ride at lower elevations will take you through the many exposed obstacles that have yet to be buried.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.Early season hazards such as rocks, trees and stumps are still visible.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Nov 14th, 2015 8:00AM