Avalanche Forecast

Issued: Jan 2nd, 2017 3:43PM

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

Avalanche Canada triley, Avalanche Canada

Wind slabs and persistent weak layers will be slow to heal due to the continued cold weather.

Summary

Confidence

High -

Weather Forecast

Some thin high cloud overnight with moderate easterly winds. Expect lows around -25. Clear and cold on Tuesday with light northerly winds and alpine highs around -18. Mostly clear on Wednesday with moderate-strong northerly winds. Cloud developing on Thursday with moderate westerly winds and a trace of snow.

Avalanche Summary

No new reports of avalanche activity. The bigger problem is the lingering deeper weakness: last week an avalanche near Corbin on a wind affected, cross-loaded slope was triggered where a fresh windslab was above weak facets. Evidence of a natural size 2.5 persistent slab avalanche was also noted on a treeline feature in the same drainage. While technically this area is in the Lizard/Flathead region, these avalanches illustrate conditions in the South Rockies. Where you get a combination of weak sugary snow lower in the snowpack and a supportive upper slab, conditions are ripe for avalanches to be human-triggered.

Snowpack Summary

Up to 20cm of new arrived Saturday night and Sunday. Moderate to strong NE winds drifted the snow into soft slabs. In general, there is very little structure to the snowpack, with low-density snow sitting over soft sugary facets. Travel is very challenging as a result. A variable interface that formed during the cold snap in early December can be found buried 30-50 cm deep. This interface consists of weak faceted (sugary) snow and preserved surface hoar in sheltered areas. The interface is likely most reactive in wind-affected terrain where it is covered by a more cohesive wind slab. Hazards such as stumps, rocks, and open creeks are still a concern.

Problems

Wind Slabs

An icon showing Wind Slabs
Recent strong winds have been from several directions, creating wind slabs and reverse loading. Expect these wind slabs to continue to be easy to trigger, and may take longer than usual to settle and bond due to the cold temperatures
If triggered the wind slabs may step down to deeper layers resulting in large avalanches.Be cautious as you transition into wind affected terrain.Avoid travelling in areas that have been reverse loaded by winds.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Persistent Slabs

An icon showing Persistent Slabs
Where denser snow overlies weak, sugary snow, there is the potential to trigger large, dangerous avalanches. Dig down and test for weak layers before committing to any steep slope.
Be aware of the potential for full depth avalanches due to deeply buried weak layers.Danger spots are where denser snow overlies weak, sugary snow below.Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 3

Valid until: Jan 3rd, 2017 2:00PM