Avalanche Forecast

Issued: Jan 19th, 2016 9:04AM

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

Avalanche Canada jlammers, Avalanche Canada

Reports of whumpfing and remote triggering indicate a weak layer buried at the beginning of January may still be sensitive to light loads. Choose conservative terrain and watch for clues of instability.

Summary

Confidence

Moderate - Wind speed and direction is uncertain on Tuesday

Weather Forecast

On Tuesday night up to 15cm of new snow may be expected with light to moderate ridgetop winds. By the afternoon, we should expect a mix of sun and cloud and light northwest winds. On Thursday and Friday a series of Pacific systems will move through the region bringing up to 15cm of new snow and strong southwest winds each day. Freezing levels should sit at valley bottom on Wednesday and then rise to about 1300m on Thursday and Friday.

Avalanche Summary

In the north of the region on Monday, a few persistent slab avalanches to size 2 were remotely triggered between 1600 and 1700m from a distances of about 5 metres. This demonstrates the sensitive nature of this instability in some areas. A skier also ski cut a size 1 persistent slab avalanche in the Kootenay Pass area. The early January surface hoar was the culprit in all of these events. New snow and wind on Tuesday night may also spark a new round of wind slab activity on Wednesday.

Snowpack Summary

Up to 15cm of new snow is expected on Tuesday night. If ridgetop winds are in the moderate to strong range, new wind slabs can be expected in upper elevation lee terrain. 40-60 cm below the surface you'll find a weak layer of surface hoar and a hard crust on steep solar aspects. This layer seems variably reactive. Some test results suggest an improving bond at this interface while remote triggering and Mountain Information Network reports of whumpfing show this layer is still sensitive to light loads in some areas. I would be increasingly cautious in areas where the overlying slab is deep and has gained cohesion through wind pressing, warming, and/or settlement. The mid and lower snowpack are generally well settled and strong.

Problems

Persistent Slabs

An icon showing Persistent Slabs
Recent storm accumulations overlie a weak layer of surface hoar. Touchy conditions may exist in areas where the recent storm snow has settled into a cohesive slab.
Be aware of the potential for large avalanches due to the presence of buried surface hoar.>Dig down to find and test weak layers before committing to a line.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 3

Wind Slabs

An icon showing Wind Slabs
Weather models indicate up to 15cm of new snow may fall on Tuesday night. If ridgetop winds are moderate or greater, new wind slabs can be expected at higher elevations.
Be alert to conditions that change with elevation.>Stay off recent wind loaded areas until the slope has had a chance to stabilize.>

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Valid until: Jan 20th, 2016 2:00PM