Register
Get forecast notifications
Create an account to receive email notifications when forecasts are published.
Login
Archived

Avalanche Forecast

Dec 8th, 2012–Dec 9th, 2012
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
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: Kootenay Boundary.

Confidence

Fair - Timing of incoming weather is uncertain

Weather Forecast

Sunday:  Warm front reaches the Interior. Snow amounts 5-10 cm, ridgetop winds W 20 km/hr , alpine temps near -5, freezing levels at 500 m.Monday: Trace of new snow, ridgetop winds W 20 km/hr, alpine temps near -6, freezing levels 900 m.Tuesday: The cold front is expected to slide down from the North bringing moderate snow fall amounts, ridgetop winds SW 30 km/hr, alpine temps near -8, freezing levels near 1000 m.

Avalanche Summary

Recent explosive control work triggered several 1.5-2.0 slab avalanches on SE-SW aspects 1700 m and above. These avalanches failed on the early December crust, that recently got buried. Please don't confuse this with the early November facet/crust layer that sits near the base of the snowpack.Any observations from the field are welcome at [email protected].

Snowpack Summary

The Kootenays have received over a metre of snow over the past week, with Kootenay Pass seeing the highest amount regionally. Regardless, current surfaces most likely include varying amounts of fairly low density storm snow which override wind slabs that formed earlier in the week. Below the recent storm snow exists a surface hoar layer that was buried at the end of November. Recent tests on this layer show CTM (SP) down 100 cm sliding on surface hoar 4-10 mm in size.Near the base of the snowpack sits the early November rain crust. This layer is most likely to be found in deeper snowpack areas at higher elevations. I'm not aware of any activity on this layer in the KB region; however, deep and destructive releases have been observed in the South Columbia region (directly to the north). Keep this on your radar, especially when traveling in areas at higher elevations that have a smooth ground cover where the existing crust is uniform and consistent. Average snowpack depths at treeline are 130-200 cm. There are significant variations in snowpack structure from one drainage to another. In short, digging down and making your own observations will be critical to safe slope selection.

Avalanche Problems

Storm Slabs

Varying amounts of new snow are likely to produce soft slab and loose snow avalanches. The weight of these avalanches may even trigger weak layers that exist deeper in the snowpack. Rider triggers are likely.
Whumpfing, shooting cracks and recent avalanches are all strong indicators of an unstable snowpack.>Be cautious of sluffing in steep terrain.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 4

Persistent Slabs

A layer of surface hoar buried at the end of November has been responsible for fairly widespread avalanche activity in some areas. Rider triggering is still likely, especially on convex rolls, and unsupported terrain.
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 - Likely

Expected Size: 2 - 5

Deep Persistent Slabs

Deep and destructive releases on the early November crust have been observed in the South Columbia Region. Although not widespread in this region, where it exists this layer may be primed for triggering.
Be aware of the potential for full depth avalanches due to a deeply buried crust.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 6