Avalanche Forecast

Issued: Dec 28th, 2016 5:30PM

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

jfloyer, Avalanche Canada

South Rockies.

Travel is reported to be challenging, so we may not have observations from the places where avalanches are most likely to occur. Be cautious if you're pushing into previously unridden areas.

Summary

Confidence

Moderate - Due to the number of field observations

Weather Forecast

THURSDAY: Mostly dry with some sunny breaks. Ridgetop winds southwest 40-60 km/h. Treeline temperatures rising to around -4C after a cold morning. FRIDAY: Mostly dry and clear. Winds becoming light northwesterly. Temperatures around -4C.SATURDAY: Flurries in the afternoon. Moderate southwesterly winds. Temperatures around -12C.

Avalanche Summary

No slab avalanches reported on Wednesday. On Tuesday, ski cutting produced a size 2 wind slab in the most recent storm snow. Natural loose dry avalanches up to size 1.5 have also been reported out of steep terrain the past few days.

Snowpack Summary

Up to 20 cm of fresh low density snow is being redistributed by southwesterly winds and forming wind slabs in the lee of ridgetops. In general, there is very little structure to the snowpack, with low density new 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 hard wind slabs. The snowpack is a generally weak and faceted below this interface, including another weak layer with surface hoar or facets that was buried in early December. Hazards such as stumps, rocks, and open creeks are still a major concern.

Problems

Wind Slabs

Expect steady strong winds to redistribute loose snow and form touchy wind slabs. If triggered, wind slabs may step down to deeper weak layers.

Be cautious as you transition into wind affected terrain.If triggered the wind slabs may step down to deeper layers resulting in large avalanches.Avoid freshly wind loaded features.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Persistent Slabs

In many places there appears to be insufficient stiffness in the slab for persistent slabs to be a concern. However, where denser snow exists, the weak facets in the lower half of the snowpack pose a concern, particularly on convex slopes.

Watch for signs of instability such as whumpfing, or cracking. Be aware of the potential for full depth avalanches due to deeply buried weak layers.Carefully evaluate and use caution around thin snowpack areas.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Dec 29th, 2016 2:00PM