Avalanche forecast

Jasper

May 9 – 10, 2019Parks Canada
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Avalanche danger

Fri
Sat
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

Soaring freezing levels and hot sun will stress a relatively cool, wintery snowpack.  The sound of natural avalanches will echo around the hills this weekend - steer clear of avalanche terrain Friday onwards. Start very early if traveling on snow.

Avalanche problems

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–3.5

    Occasional cornice falls are expected, increasing into the weekend. some of these may trigger large slab avalanches, running well down into lower elevations. 

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1.5–3

    Weak mid-pack facets and upper-snowpack crusts will become more reactive, especially on shaded, wind-sheltered slopes. This may morph into a Wet Slab problem on solar aspects, as water accumulates above strong crusts.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely - Very Likely
    Size
    1–2

    Springs' increasing influence is encouraging the upper snowpack to shed recent snowfall, in loose snow avalanches. Steer away from avalanche terrain as the upper snowpack becomes wet, and you are sinking in to bootop or deeper.

Weather Forecast

Freezing level soaring, with valley bottom highs forecast in the 20's.  Generally scattered cloud, warm overnight temperatures.

Thursday: Mainly sunny, Treeline low -1, high 6 °C, Light NW winds, Freezing level 3100 metres.

Friday: Treeline low 2.5, High 7. freezing level 3000m.

Saturday: Treeline Low 5, High 1, freezing level 3500m1

Snowpack Summary

Surface layers becoming wet daily, as the snowpack is forced to transition rapidly from Winter to Spring.  Snow from frequent small Spring storms has settled quickly, but overlies crusts and facets in the upper snowpack. The crusts are thick on solar aspects.  The snowpack remains faceted on shady aspects, and weak in shallow areas.

Avalanche Summary

On Wednesday, numerous small (size 1-1.5) loose wet avalanches were observed on N and E aspects near Jasper townsite.  On Sunday, a large (size 2.5) natural slab avalanche was observed at 2400m on a NE aspect of Pyramid Mountain. 

Confidence

Due to the number of field observations

Regions covered