Avalanche Forecast

Issued: Feb 4th, 2015 8:00AM

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

danyelle magnan, Parks Canada

Glacier.

A touchy storm slab is developing with continued light snowfall and moderate southerly winds. Danger will rise rapidly by Friday when we get hammered by a warm, pacific storm.

Summary

Weather Forecast

Today expect flurries, with accumulations up to 5cm. Moderate SW winds will continue to load lee slopes. Snowfall intensity will increase on Thursday, with up to 15cm of snow, gusty S'ly winds, and freezing levels rising to 1700m. Heavy snowfall is expected on Friday with up to 35cm of snow, and strong SW winds. Freezing levels rise to 1800m.

Snowpack Summary

30-50cm sits on the Jan 30 surface hoar/crust layer. Expect to find the Jan 30 crust up to 2200m. Snowpack tests indicate that the storm slab may bond poorly to the crust, which acts as a smooth bed surface. Jan 15 surface hoar layer is down 70-110cm and the December 17 is down 140-190 cm. Windloading will increase slab properties in lee areas.

Avalanche Summary

Yesterday, skiers accidentally triggered a size 2.5 avalanche from a SE aspect at 2120m. The avalanche propagated ~200m wide and ran up to 600m. Along the highway one size 3 and numerous size 2-2.5 natural avalanches were observed, occurring from all aspects generally above 1800m. Recent activity is occurring on the Jan 30 crust.

Confidence

Problems

Storm Slabs

At treeline and above a soft slab is forming which sits on a firm bed surface. This storm slab is triggerable, and may propagate widely. In areas sheltered from the wind the loose storm snow may sluff on steep slopes, gaining mass.

Use safe ski cutting techniques before entering ski run. Ski short pitches and regroup in safe spots.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 3

Persistent Slabs

The January 15 surface hoar layer is down 70-110cm. Large triggers, like a cornice fall or other avalanches, are likely required to trigger this layer. Rapid loading forecast by Friday may reactivate this layer.

Pay attention to overhead hazards like cornices.If triggered the storm slabs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 4

Valid until: Feb 5th, 2015 8:00AM