Avalanche forecast

Lizard-Flathead

Mar 3, 2018Avalanche Canada
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Archived · expired 9 years ago

Avalanche danger

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

Greater than forecast snowfall has increased the avalanche danger to HIGH. Carefully manage terrain that can produce loose dry avalanches and watch closely for signs of slab formation in the new snow.

Avalanche problems

  • Loose Dry

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely - Certain
    Size
    1–2
    Deep accumulations of new low density snow will release easily in loose dry avalanches on Saturday. This will occur naturally in steep terrain, as well as with human triggers. Watch for terrain traps where sluffs can form deep deposits.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely - Very Likely
    Size
    1–2.5
    New snow and wind will continue to form slabs over Saturday. Wind exposed areas will likely see the most rapid slab development and greatest slab reactivity. Stick to supported, sheltered slopes and watch diligently for signs of slab formation.

Confidence

High -

Weather Forecast

Friday night: Continuing flurries bringing about 10 cm of new snow. Mainly light southwest winds, increasing to strong at ridgetop.Saturday: Continuing flurries bringing about 10 cm of new snow. Mainly light southwest winds, moderate to strong at ridgetop. Alpine high temperatures of -7.Sunday: Mainly cloudy with isolated flurries and a trace of new snow. Light variable winds. Alpine high temperatures of -9.Monday: Mainly cloudy with isolated flurries and a trace of new snow. Light to moderate west winds. Alpine high temperatures of -10.

Avalanche Summary

Storm snow has grown touchy cornices and formed widespread soft storm slabs near ridge tops and open areas at treeline and below. On Thursday morning, explosives control in the Fernie area produced loose dry and storm slab releases reaching size 1.5. Continuing control in the afternoon produced results to size 2.5 with slabs of up to 80 cm in depth.On Wednesday there were reports of several natural and skier triggered size 1 loose, dry storm snow releases on all aspects above 1700 m, as well as a few size 2-2.5 natural storm slab releases on northeast aspects that where possibly cornice triggered.Tuesday a size 2.5 natural storm slab release that was likely triggered by a cornice collapse, was reported on a northerly aspect in the alpine. Cornice collapses up to size 1.5 were also reported but did not produce slab releases on the slopes below.Numerous wind slabs up to size 2 and loose dry avalanches up to size 1.5 were reported from the Lizard Range on Monday running either naturally or triggered by skiers testing small slopes. Explosives triggered widespread storm slabs up to size 1.5 and size 2 results on northerly aspects. Crown depths typically ranged from 40-80 cm.

Snowpack Summary

50-60 cm of new low density accumulated in the region over Friday night. This brings snowfall totals from the past week to about 100 cm. This storm snow overlies various old surfaces including old hard wind slabs, crusts, facets and more isolated surface hoar. Also in the upper to mid snowpack, a surface hoar layer buried mid-February is now 80 to 100 cm below the surface on sheltered northerly aspects.Deeper in the snowpack, the widespread mid-December weak layer sits about 200 cm deep. This consists of a crust, facets or surface hoar.Near the base of the snowpack, a crust/facet layer could be awoken from a thin-spot trigger point, or with a very large load like a cornice fall.

Regions covered