Avalanche Forecast

Issued: Mar 26th, 2016 8:00AM

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

danyelle magnan, Parks Canada

Glacier.

There were a lot of skier triggered avalanches yesterday! Hazard can increase rapidly during sunny breaks. Remember that other groups may be above or below you & regroup in safe spots. Avoid slopes exposed to large cornices above when the sun is out.

Summary

Weather Forecast

Unsettled weather, with generally mild temps, is expected through the weekend. Today will be cloudy, but strong solar radiation is expected during sunny breaks. Sunday is expected to be cloudy, with flurries bringing ~5cm. Monday will be mostly sunny, with alpine temps reaching 0'C. Below treeline, mild temps will prevent an overnight recovery.

Snowpack Summary

~50cm of snow in the past 5 days, combined sustained SW winds, is building a storm slab that is up to 1m deep on lee slopes. This slab overlies a crust, which provides a good sliding surface, on all aspects. Mild temps and periods of strong solar are making it reactive. Avalanches may step down to multiple crusts in the top meter.

Avalanche Summary

There were lots of skier triggered avalanches yesterday. A size 3 was accidentally triggered on the "Thorington", NE aspect ~2700m. It was ~1m deep and ran ~1km on the crust. Several size 2's were also triggered, they were up to 40cm deep running up to 500m. A lower elevations wet slabs were triggered. Luckily no-one was involved in any of them!

Confidence

Timing or intensity of solar radiation is uncertain

Problems

Storm Slabs

A touchy storm slab exists, with 30-50cm over a crust. On lee and cross-loaded features it's up to 1m deep. Yesterday skiers easily to triggered several size 2's and one size 3. They occurred in predictable places; steep slopes with a convexity.

Choose well supported terrain without convexities.Be careful with wind loaded pockets, especially near ridge crests and roll-overs.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

2 - 3

Persistent Slabs

A series of crusts on solar aspects, buried up to 1.2 m deep, remain a concern. Tests generally take a hard force but continue to produce sudden planar results. This suggests that smaller avalanches, or cornice failures, may trigger large avalanches.

If triggered the storm slabs may step down to deeper layers resulting in large avalanches.Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.

Aspects: North, North East, East, South East, South, South West.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 3

Loose Wet

There has not been an overnight freeze below tree-line for several days. Expect avalanches to be easy to trigger on steep slopes where moist snow overlies a crust. While unlikely to be large, avalanches will gain mass in gulleys and terrain traps.

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

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Mar 27th, 2016 8:00AM