Avalog Logo

Avalanche Canada esharp, Avalanche Canada

South Rockies Avalanche Forecast

Feb 2nd, 2016 8:15AM

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.

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

Wednesday: flurries, light westerly winds, -8C at 1500m. Thursday: isolated flurries, moderate westerly winds, a possible above freezing level between 1000m and 1550m, Friday: flurries without significant accumulations, moderate westerly winds, freezing level between 1500 and 1700m.

Avalanche Summary

No new avalanche observations over the weekend from this region. On Friday, our field team reported several natural avalanches up to size 3.0 on east aspects that were visible from Crown Mountain in the Elk Valley North area. These avalanches were probably triggered by wind loading or cornice falls. The interesting observation about these slides was that they stepped down in the track or at the fans around 1900 meters elevation and resulted in a larger avalanche than the initial release.

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

An icon showing Wind Slabs

Likelihood

Possible

Expected Size

1 - 3
Moderate westerly winds have develop wind slabs in the alpine and at treeline.
Avoid freshly wind loaded features. >Be aware of the potential for wide propagations due to the presence of hard windslabs. >Use ridges or ribs to avoid pockets of wind loaded snow. >

Aspects:

North, North East, East, South East, South.

Elevations:

Alpine, Treeline.

Persistent Slabs

An icon showing Persistent Slabs

Likelihood

Possible - Unlikely

Expected Size

3 - 5
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, or from triggering by smaller avalanches in motion.
Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>

Aspects:

All aspects.

Elevations:

All elevations.

Valid until: Feb 3rd, 2016 2:00PM