Archived

Avalanche Forecast

Nov 30th, 2017–Dec 1st, 2017

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Regions: Kootenay Boundary.

This forecast is based on very few field observations and a high level of uncertainty exists. A conservative approach to terrain selection is critical until more snowpack data becomes available.

Confidence

Moderate - Due to the number of field observations

Weather Forecast

Friday: 5-10cm of new snow / Moderate southwest winds / Freezing level at 1100mSaturday: Mix of sun and cloud / Light and variable winds / Freezing level at 1000mSunday: Overcast skies / Light and variable winds / Freezing level at 800m

Avalanche Summary

On Tuesday a naturally-triggered size 1 storm slab was observed around Kootenay Pass. The avalanche occurred on a southeast aspect at about 2100m, and is thought to have failed on the recently buried crust. A natural storm slab avalanche cycle is expected to have occurred on Wednesday and Thursday in response to recent wind and snowfall. The possibility of human triggering these storm slabs may continue into the weekend.We currently have very limited observations in this region. Please submit your observations to the Mountain Information Network (MIN).

Snowpack Summary

Up to 40cm of new snow has fallen since last weekend. At higher elevations, southerly winds (gusting strong at times) likely redistributed the new snow, forming wind slabs on lee features.Below the recent storm snow you'll likely find a couple of widespread crusts which formed as a result of last week's rain. Last week's heavy rain to the mountaintops really shrunk the snowpack and has transitioned much of the snowpack from dry to moist snow. The depth of the snowpack varies greatly with elevation. Recent reports suggest the average depth is 100-170cm in the alpine, 50-100cm at treeline, and decreasing rapidly below treeline where the primary hazards are rocks, stumps, and open creeks. We currently have very limited snowpack observations within this region and it is critical to supplement this information with your own observations.

Avalanche Problems

Storm Slabs

Recent wind and snowfall has likely formed touchy new storm slabs. Storm slabs may be more reactive in heavily wind-exposed terrain, or in areas where the new snow has a weak bond with underlying crusts.

Be cautious as you transition into wind affected terrain.The new snow may require several days to settle and stabilize.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2