Avalanche Forecast

Issued: Nov 26th, 2017 3:28PM

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.

mgrist, Avalanche Canada

Kootenay Boundary.

The effects of warm temperatures and rain on the snowpack may linger into Monday. 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

There may be some lingering flurries on Monday with more seasonal temperatures. The next system arrives on Tuesday, with lower freezing levels than we've been seeing lately. 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.WEDNESDAY: Clearing throughout the day. Moderate westerly ridgetop winds. Freezing level around 1200 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

Approximately 4-6 cm of snow fell Saturday night into Sunday, followed by rapidly warming temperatures on Sunday morning (to +3 Celsius at ridge crest in many locations).This new snow (or what's left of it) sits on the thick Nov 23rd rain crust, that formed at the end of last week's Atmospheric River (aka Pineapple) event. 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. Last week's heavy rain to the mountaintops really shrunk the snowpack and has transitioned much of the snowpack from dry to moist snow. A major feature in the snowpack is a crust which formed at the end of October and may exist approximately 30cm above the ground in some locations. That said, the thick November 23rd 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

The rain and warm temperatures from Sunday could remain a factor in the upper snowpack depending on how quickly it cools off overnight into Monday. 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: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Persistent Slabs

Recent rain to mountaintops combined with overnight cooling has reduced the likelihood of triggering this layer. Areas in which the snowpack above this layer remained dry should be treated with increased caution.

Avoid shallow snowpack areas where triggering is more likely.Use increased caution in areas which did not form a surface crust.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Nov 27th, 2017 2:00PM