Avalanche forecast

Purcells

Mar 20, 2018Avalanche Canada
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Archived · expired 9 years ago

Avalanche danger

Wed
Thu
Alpine
1 · Low
Treeline
1 · Low
Below
1 · Low

Highlights

It's a good day for travel in the mountains. Normal cautions will help you to manage lingering cornices and small avalanche problems.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5
    Small new wind slabs have formed in the immediate lee of ridgecrests and wind-exposed features. Slabs my be more reactive where they have buried a new layer of surface hoar. Small loose snow releases become likelier with daytime warming.

Confidence

High -

Weather Forecast

Tuesday: Mainly cloudy with isolated flurries and a possible trace of new snow. Light southwest winds. Freezing level to 1600 metres with alpine temperatures around -4.Wednesday: Mainly cloudy with isolated flurries and a possible trace of new snow. Light south winds, increasing overnight. Freezing level to 1700 metres with alpine high temperatures around -3.Thursday: Cloudy with flurries bringing 5-10 cm of new snow, increasing overnight. Light to moderate southeast winds. Freezing level to 2000 metres with alpine high temperatures around 0.

Avalanche Summary

On Saturday there were reports of small (size 1) skier and sled triggered slab avalanches (15 - 25 cm deep) on north and northeast aspects in the alpine. Explosive control work also produced several cornice failures up to size 2.5 that entrained loose snow on the slopes below but no deeper slab releases.Explosive control work last Friday produced size 1.5 slab avalanches averaging 20-60 cm deep on steep northerly features at treeline.

Snowpack Summary

Recent light snowfalls (5-15 cm each) have been followed by warm daytime temperatures and glimpses of sun, setting up a couple of thin storm snow layers over temperature and sun crusts at lower elevations and on south aspects. On shaded aspects at higher elevations, Sunday's snowfall buried a layer of surface hoar now found 10-15 cm deep.New snow amounts taper with elevation and below 1700 m, only minimal accumulations have buried a supportive crust on all aspects. This crust will likely break down with daytime warming, becoming moist in the afternoon. Deeper persistent weak layers from mid-late February (down 40 -100 cm deep) as well as January and December layers are generally considered dormant, but could wake up with a surface avalanche stepping down, cornice fall, or a human trigger in a shallow or variable-depth snowpack area. These layers consist of sun crust, surface hoar and/or facets. Facets also linger at the base of the snowpack.

Regions covered