Avalanche Forecast

Issued: Jan 22nd, 2015 8:00AM

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

danyelle magnan, Parks Canada

Glacier.

A touchy layer, with remote triggering potential means that you need to be aware of who is above and below you, minimize your exposure, and regroup in safe spots. Cautious terrain selection and good group management are essential.

Summary

Weather Forecast

Flurries are starting as a series of weather systems move into the region. Today expect trace of snow, with moderate SW winds and freezing levels rising to 1300m. Steady snow starts on Friday; we expect 25cm by the end of the day with freezing levels to 1600m and strong winds. Sat expect another 14cm, freezing levels at 1700m and moderate SW winds.

Snowpack Summary

A 60cm slab sits on the Jan 15 surface hoar. It will be deeper in lee features where loaded by south winds. The Jan 15 was widespread, largest at treeline, and on solar aspects sits on a sun crust. Tests indicate it is likely to be triggered (CTE SC) and propagate (PST 29/100 end). The Dec 17 surface hoar is down 100-150cm and stubbornly reactive.

Avalanche Summary

On Tuesday artillery control triggered over 30 size 2 to 3.5 avalanches from all aspects between 17-2700m. Notables were size 3.5's from the W face of Cheops and off Mt Tupper that ran into the creeks. Human triggered avalanches up to size 2.5 continue to occur in the region. Remote triggering from up to 300m has been reported.

Confidence

Timing of incoming weather systems is uncertain

Problems

Persistent Slabs

A 60cm+ thick cohesive slab now overlies a touchy surface hoar layer. Tests indicate that it may be triggered by light loads (ie you) and likely to propagate widely as the slab stiffens. Avalanches have been remotely triggered from up to 300m away.

Watch for whumpfing, hollow sounds, and shooting cracks.Use conservative route selection, choose moderate angled and supported terrain with low consequence.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 3

Wind Slabs

Strong southerly winds during the storm, with lots of low density snow available for transport, will have formed windslabs in lee areas. These deep pockets of windslab may overlie the touchy surface hoar layer.

Avoid freshly wind loaded features.Be cautious as you transition into wind affected terrain.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Persistent Slabs

A surface hoar layer, down 1-1.5m, that was buried in mid December continues to be reactive. Avalanche control had a few avalanches stepping down to this layer, even in areas where it had been previously controlled. The new load may wake it up again.

Dig down to find and test weak layers before committing to a line.Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

3 - 4

Valid until: Jan 23rd, 2015 8:00AM