Avalanche forecast

Lizard-Flathead

Jan 27, 2018Avalanche Canada
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Archived · expired 9 years ago

Avalanche danger

Sun
Mon
Alpine
4 · High
Treeline
4 · High
Below
3 · Considerable

Highlights

The combination of recent heavy snowfall and buried weak layers has created very dangerous avalanche conditions. Several large, destructive avalanches have occurred in the past week. Travel in avalanche terrain is not recommend.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    2–4
    Several weak layers of concern are buried within the snowpack and produced several recent large and very large avalanches. Simple terrain with low angle, supported slopes is a good choice.
  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    1–2.5
    New snow and has formed touchy storm slabs, while winds are building cornice and loading lee slopes near ridge top. These slabs have shown the potential for wide propagations and running long distances.

Confidence

Moderate - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

TONIGHT: Cloudy, light flurries. Accumulation 3-8 cm. Ridge wind light, southwest. Temperature -10. Freezing level valley bottom.SATURDAY: Cloudy, flurries. Accumulation 5-10 cm. Ridge wind light to moderate southwest. Temperature -4. Freezing level valley bottom.SUNDAY: Cloudy, light flurries. Accumulation trace. Ridge wind light southwest. Temperature -4. Freezing level valley bottom. MONDAY: Cloudy, flurries. Accumulation 5-15 cm. Ridge wind strong, southwest. Temperature +1. Freezing level rising to 1900 m.

Avalanche Summary

Several large and very large avalanches have occurred in the past five days highlighting that very dangerous avalanche conditions exist within the region.Explosive control work on Friday produced numerous large and one very large, Size 4, deep slab avalanche that failed on the mid-December layer, 250 cm deep, on a northeast slope at 2100 m. This avalanche destroyed several large trees and ran well below treeline to the full extent of the runout zone.On Wednesday and Thursday, numerous natural, skier and explosive triggered storm slab avalanches up to Size 3 were reported with crowns from 20-80 cm deep, and propagations from 20 up to 150 m wide.On Tuesday a Size 2 was triggered from 50 m away by a snow machine on a northeast aspect at 2050 m. The crown was 120 cm deep and is suspected to have failed on the mid-December weak layer.Reports from Monday included seven deep persistent slabs that were released with small explosives in the alpine in the Fernie area. Sizes ranged from 2.5-3, crown depths averaged about 200 cm and all results indicated the deeply buried late-November crust as the failure plane.

Snowpack Summary

About 60-80 cm of settled storm snow now covers a layer of surface hoar on sheltered aspects (especially prominent from 1400-1900 m) and sun crust on solar aspects, that was buried mid-January. Beneath the mid-January interface lie a number of very concerning buried weak layers. A layer of surface hoar from early-January is buried 90-110 cm below the surface. A weak layer buried mid-December (predominantly surface hoar and/or a sun crust) is around 120-160 cm below the surface at treeline and below treeline elevations. A rain crust with sugary facets that developed late-November is near the bottom of the snowpack and is now buried 200-250 cm below the surface. All of these layers remain active and have produced recent large, destructive avalanches.

Regions covered