Avalanche Forecast

Issued: Mar 19th, 2015 8:02AM

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 Loose Wet.

danyelle magnan, Parks Canada

Glacier.

Avalanche danger will rise through the day as new snow accumulates in the alpine, and moderate winds magnify loading on lee slopes. Be conservative in terrain selection and diligent in your group management.

Summary

Weather Forecast

Today expect flurries with freezing levels rising to 1700m. Up to 12cm of snow are expected, magnified by moderate to strong SW winds. On Friday, expect another 13cm with freezing levels at 1900m and moderate S winds. Saturday will be similar with another 9cm of snow.

Snowpack Summary

5cm of new snow will bury, and hide, a variety of surfaces from sun crusts to reactive windslabs. The upper snowpack is a complex mix of crusts, weak facetted snow and surface hoar. Below 1800m the snowpack is spring-like with a weak melt-freeze crust forming. Rain at lower elevations will destabilize the snowpack.

Avalanche Summary

On Tuesday skiers triggered a slab avalanche on Youngs Peak. It was on a N aspect, ~2100m, was reported to be 15-60cm deep, 30m wide and 100m long. In the region, windslabs have been triggered by riders daily causing avalanches to size 2. Whumphing continues to be reported from treeline areas throughout the park.

Confidence

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

Problems

Wind Slabs

Touchy windslabs continue to be reactive to human triggering. They are most likely to be triggered from a convexity and may propagate widely. The buried windslabs will be harder to identify, and new slabs are forming with the new snow and wind.

Watch for whumpfing, hollow sounds, and shooting cracks.Use caution in lee areas. Recent wind loading have created wind slabs.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Persistent Slabs

The upper snowpack is complex, with a multitude of crusts, weak facetted layers, and surface hoar. Large slab avalanches continue to sporadically occur on these layers. Cornices are large and fragile and if they fail provide a large trigger.

Be aware of the potential for large, deep avalanches.Choose well supported terrain without convexities.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 3

Loose Wet

At lower elevations the snowpack is weak and spring like. Warm overnight temperatures have prevented an overnight freeze. If snow turns to rain it will rapidly weaken the snowpack.

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

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Mar 20th, 2015 8:00AM