Avalanche Forecast

Issued: Mar 13th, 2015 8:11AM

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

andrew jones, Parks Canada

Glacier.

Avoid sun exposed slopes and overhead cornice hazard this afternoon as warm temperatures and solar input continue to weekend the snowpack.

Summary

Weather Forecast

Sun and warm temperatures will have a profound effect on the snowpack today. Freezing levels will rise this afternoon to around 2800m, bringing warm air high in to the alpine. A pacific frontal system arrives later this evening with wet flurries, strong south winds and slightly cooler temperatures. Up to 20cm of wet snow is expected for Saturday.

Snowpack Summary

Temperatures remained warm overnight, leading to a poor refreeze. 10cm of recent snow in the alpine overlies a sun crust on solar aspects and wind slabs and crusts on shaded slopes. Strong southerly winds have formed new wind slabs. Crusts in the top 20cm are weakening with continued warm temps and triggering of deeper layers is possible.

Avalanche Summary

A natural cycle of loose wet avalanches was observed yesterday in the highway corridor, up to size 2.5. Warm temperatures will continue to destabilize the snowpack throughout today. Yesterday skiers reported feeling a large whumph on the approach to Little Sifton Col, prompting the group retreat.

Confidence

Intensity of incoming weather systems is uncertain

Problems

Wind Slabs

New moist snow with strong southerly winds have formed new wind slabs in the alpine. They may bond poorly in areas where they overly crusts, or may be hiding deeper old wind slabs. Continued warm temps are making the old wind slabs more reactive.

Avoid freshly wind loaded features.Be careful with wind loaded pockets, especially near ridge crests and roll-overs.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Loose Wet

A poor overnight re-freeze combined with ongoing warm temperatures and sunshine will continue to destabilize the upper snowpack. The weak, moist surface snow may be easily triggered on steep slopes, gaining mass and traveling long distances.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Persistent Slabs

Deep instabilities in the snowpack have been dormant in recent weeks but may become reactive. The bridging properties of near surface crusts weaken as the snowpack warms. New snow tonight will make persistent slabs a key problem for the weekend.

Be aware of the potential for large, deep avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

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