Avalanche forecast

Lizard-Flathead

Mar 24 – 25, 2019Avalanche Canada
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Archived · expired 8 years ago

Avalanche danger

Tue
Wed
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

Small loose wet avalanches may gather mass, become much larger, and run farther into low angle terrain than expected.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    1.5–2.5
    Human triggering of large persistent slab avalanches are most likely on north facing slopes in rocky, alpine terrain with a shallow or highly variable snowpack depth.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2
    This problem is more likely at lower elevations where there was a weak or no overnight re-freeze. Sunshine and air temperatures above 0 C can rapidly increase the likelihood of triggering loose wet avalanches.

Confidence

Moderate - Due to the number of field observations

Weather Forecast

SUNDAY NIGHT: Cloudy / Light, southwesterly winds / Alpine low -3 C / Freezing level 1200 m.MONDAY: Mix of sun and cloud / Light, southwesterly winds / Alpine high 2 C / Freezing level 2000 m.TUESDAY: Cloudy with flurries (rain below approx. 1400 m.); 3-5 mm. / Moderate to strong, southwesterly winds / Alpine high -1 C / Freezing level 1600 m.WEDNESDAY: Mix of sun and cloud / Light, northeasterly winds / Alpine high 0 C / Freezing level 1500 m.

Avalanche Summary

On Sunday, there was a report near Fernie of a skier triggered, size 2.5 wet slab avalanche that began as a loose wet avalanche and then gathered mass which ran much further than expected through low angle terrain. The below link shows a smaller example of this sort of avalanche.Thursdays reports show continued skier triggered loose wet avalanches reaching size 1.5 on sun-exposed aspects. Check out this video of our South Rockies Field Team HERE.On Wednesday, several avalanches that began as loose wet point releases, then triggered small slabs which entrained or gouged out additional mass, significantly increasing the size and destructive potential of the avalanche.

Snowpack Summary

The prolonged warm spell has transitioned sun exposed slopes in the alpine and all aspects at treeline and below towards becoming isothermal (0 C throughout the snowpack). In these areas that have entered spring conditions, the avalanche hazard will fluctuate greatly depending on the strength of the overnight freeze and how quickly the snowpack is warmed up each day. Check out this guide to managing avalanche hazard during spring conditions HERE.In areas that remained more sheltered from the heat, like northerly aspects in the alpine, there may still be a dry snowpack with a well settled slab sitting on weak facets (sugary snow). Human triggering of persistent slabs on this layer may still be possible; especially in rocky alpine terrain with a shallow or highly variable depth snowpack.

Regions covered