Avalanche forecast

Kootenay Boundary

Jan 3 – 4, 2015Avalanche Canada
View on map
Archived · expired 12 years ago

Avalanche danger

Mon
Tue
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
Open full map

Highlights

Recent snowpack and avalanche observations from the Rossland Range indicate that the Danger Rating below treeline is CONSIDERABLE in that area. The Special Public Avalanche Warning is extended through the weekend.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–3
    Strong winds have formed hard and potentially reactive wind slabs in exposed terrain.  Due to the reverse loading pattern, wind slabs may be triggered in unsuspecting locations.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–4
    A widespread persistent weak layer continues to react to light loads with the potential for large avalanches. Conservative terrain selection remains critical.

Confidence

Fair - Intensity of incoming weather systems is uncertain on Sunday

Weather Forecast

A pacific frontal system will enter the region on Sunday. Moderate to heavy snowfall is expected by Sunday evening and should continue until Monday night. Mainly light flurries are forecast for Tuesday. Winds should remain strong to extreme from the west throughout the forecast period. Weather models are currently disagreeing on forecast temperatures. On Sunday confidence is good, and freezing levels should remain at valley bottom. Monday and Tuesday is where uncertainty lies with some models calling for freezing levels rising to  1250m. We should have a better handle on this by Sunday.

Avalanche Summary

In general, persistent slab avalanches to size 2 continue to occur in the Kootenay Boundary region. On Saturday, skiers accidentally triggered size 1 slabs around treeline in the Selkirks and the Monashees. Both avalanches failed on the mid-December layers.The mid-December layer remains the most concerning, and with new snow in the forecast avalanche danger will be on the rise at ALL elevations.

Snowpack Summary

Light amounts of low density snow overlie a variety of snow surfaces. Wind exposed slopes are showing firm wind pressing, or a scoured exposed crust, while sheltered locations have up to 35 cm of light, low density, faceted snow above recently formed surface hoar. Stiff and reactive wind slabs exist primarily on southerly aspects. Up to 80 cm below the surface, you'll likely find a touchy weak layer of surface hoar sitting on a thick rain crust. This widespread persistent weakness was buried mid-December and continues to produce whumpfing and sudden planar characteristics in snowpack tests. Although high elevation slopes may not have the rain crust, they are still reported to have touchy buried surface hoar. At the base of the snowpack, a crust/facet combo appears to have gone dormant for the time being.

Regions covered