Avalanche Forecast

Issued: Nov 25th, 2017 4:46PM

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

Avalanche Canada mgrist, Avalanche Canada

Rain may weaken the upper snowpack Sunday afternoon. Due to limited data it is CRITICAL to supplement this information with your own observations. Please post your observations to the MIN.

Summary

Confidence

Moderate - Due to the number of field observations

Weather Forecast

The next weather system will initially bring rain on Sunday afternoon, changing to snow and lingering light flurries early next week. SUNDAY: 10-20 mm rain giving way to 5-10cm snow late Sunday. Moderate to strong southwesterly ridgetop winds. Freezing level around 2500 m lowering to surface overnight. MONDAY: Cloudy with isolated flurries. Light to moderate westerly ridgetop winds. Freezing level around 1000 m.TUESDAY: Flurries (10-15cm possible). Light-moderate southerly ridgetop winds. Freezing level around 1000 m.

Avalanche Summary

No new avalanches reported; however, we currently have very limited observations in this region. Please submit your observations to the Mountain Information Network (MIN).

Snowpack Summary

A new crust formed on Thursday as temperatures cooled and the rain-soaked snow surface froze and then was covered by 5-10cm of snow at treeline and above. The depth of the snowpack varies greatly with elevation. Recent reports suggest the average depth is 100+cm in the alpine, 50-100cm at treeline, and decreasing rapidly below treeline where the primary hazards are rocks, stumps, and open creeks. Recent heavy rain to the mountaintops has rapidly shrunk the snowpack and has transitioned much of the snowpack from dry to moist snow. The major feature in the snowpack is a crust which was formed at the end of October can be found approximately 30cm above the ground in some locations. That said, the new surface crust will temporarily reduce the likelihood of triggering on this layer. We currently have very limited snowpack observations within this region and it is critical to supplement this information with your own observations.

Problems

Loose Wet

An icon showing Loose Wet
The precipitation on Sunday will start as rain, which could saturate the upper snowpack. Even a small avalanche can push you into terrain traps.
Watch out for wet sloughs in steep terrain, particularly where the debris flows into terrain traps.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 2

Persistent Slabs

An icon showing Persistent Slabs
Recent rain to mountaintops combined with overnight cooling Thursday night has reduced the likelihood of triggering this layer. Areas in which the snowpack above this layer remained dry should be treated with increased caution.
Use increased caution in areas which did not form a surface crust.Avoid shallow snowpack areas where triggering is more likely.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Nov 26th, 2017 2:00PM

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