Avalanche Forecast

Issued: Feb 3rd, 2016 8:21AM

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

jsmith, Avalanche Canada

South Rockies.

Wind slabs continue to be a concern for human triggering, and a buried persistent weak layer has been active in isolated locations during the past week.

Summary

Confidence

Moderate - Due to the number of field observations

Weather Forecast

Thursday: Isolated flurries, moderate to strong westerly winds, freezing level around 1000m. Friday: Flurries without significant accumulation, moderate westerly winds, freezing level between 1500 and 1700m. Saturday: Flurries with Moderate westerly winds and freezing levels 1000-1500m.

Avalanche Summary

No new avalanche observations from this region.

Snowpack Summary

3 to 5 cm of new snow has fallen in the last week. Depending on where you are riding you may find either pockets of lingering wind slab or extensive wind effect at treeline and in the alpine. A persistent weak layer of buried surface hoar can be found buried at variable depths depending on elevation. For example our field team found it down 45 cm at 1850 meters and down 90 cm at 2150 meters in the Crown Mountain area, where compression tests gave hard sudden planar results. A weak crust/facet layer from early-December can typically be found down over 1m. It has become difficult to trigger this layer but it is still reactive in snowpack tests suggesting that it remains capable of wide propagations and large destructive avalanches. Below 1700m the most recent snow hides a melt-freeze crust.

Problems

Wind Slabs

Moderate westerly winds have developed wind slabs in the alpine and at treeline.

Use ridges or ribs to avoid pockets of wind loaded snow. >Be aware of the potential for wide propagations due to the presence of hard windslabs. >Avoid freshly wind loaded features. >

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Persistent Slabs

A persistent weak layer of buried surface hoar on the west side of the region and a buried crust/facet combination on the east side of the region continues to be a concern for human triggering in thin spots where the layer is closer to the surface.

Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

3 - 5

Valid until: Feb 4th, 2016 2:00PM