Avalanche Forecast

Issued: Feb 1st, 2016 8:18AM

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.

Avalanche Canada esharp, Avalanche Canada

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

Summary

Confidence

Moderate - The weather pattern is stable on Tuesday

Weather Forecast

Tuesday: mainly sunny, no snowfall, light westerly winds, -5Cat 1550m, Wednesday: mainly sunny, no snowfall, light westerly winds, -8C at 1500m, Thursday, Cloudy with isolated flurries, no significant accumulation, light to moderate westerly winds, freezing level rising to 1500m.

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

I suspect that a supportive melt-freeze crust has developed below about 1600 meters due to the recent cooling trend. Recent strong to extreme winds have resulted in extensive wind effect in the alpine and at treeline, scouring lee slopes, loading lee features and forming fresh cornices. 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 it remains capable of wide propagations and large destructive avalanches.

Problems

Wind Slabs

An icon showing Wind Slabs
Moderate westerly winds haveĀ  develop 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

An icon showing 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, 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.

Likelihood

Possible

Expected Size

3 - 5

Valid until: Feb 2nd, 2016 2:00PM

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