Avalanche forecast

Lizard-Flathead

Mar 7 – 8, 2021Avalanche Canada
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Archived · expired 6 years ago

Avalanche danger

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

In areas where the snow surface stayed dry during the heatwave, or there is a breakable crust present, triggering avalanches remains a possibility. In areas where the surface has frozen into a thick crust that supports your weight, avalanches are unlikely.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–3

    Two persistent weak layers exist in the snowpack. The upper layer is down 30-50 cm and consists primarily of facets. The deeper layer is down 60-100 cm. This layer consists of surface hoar, facets, and/or a crust. The problem has been most prevalent around treeline and in openings below treeline, but also reaches into the lower alpine. 

    In areas where the snow is dry (soft or wind-affected), or where a breakable crust exists, it may still be possible to trigger a persistent slab.

Confidence

Moderate - Uncertainty is due to how quickly the snowpack will recover and gain strength.

Weather Forecast

SATURDAY NIGHT - Mainly cloudy with isolated flurries / moderate west wind / alpine low temperature near -6 / freezing level 1500 m and dropping to valley bottom

SUNDAY - Cloudy with sunny periods and a few flurries, up to 5 cm / moderate to strong southwest wind / alpine high temperature near -5 / freezing level 1500 m and dropping to valley bottom overnight

MONDAY - Sunny with cloudy periods / light west wind / alpine high temperature near -5 / freezing level 1500 m and dropping to valley bottom overnight

TUESDAY - A mix of sun and cloud / light southwest wind / alpine high temperature near -6 / freezing level 1500 m and dropping to valley bottom overnight

Avalanche Summary

There were no new avalanches reported on Saturday, at the time of publishing.

On Friday, there were a few reports of natural and human-triggered wet loose avalanches up to size 1.5, explosive triggered cornices up to size 2, and one explosive triggered size 2 persistent slab avalanche on a northeast aspect.

On Thursday, there were several reports of natural loose wet avalanches up to size 1.5 as well as natural and human-triggered wind and wet slab avalanches up to size 2. There were also a few reports of size 2.5 natural persistent slab avalanches in the nearby Waterton National Park region.

On Wednesday there were several reports of natural size 1 wet loose avalanches on solar aspects in the afternoon.

Snowpack Summary

Previous warm temperatures followed by a re-freeze created a crust on the surface in many areas, which has now been covered by a dusting of fresh snow. Dry snow may still be found on north aspects at upper elevations. Wind slabs are likely still present on northerly aspects in the alpine and at treeline. 

Up to 50 cm of snow sits above a variety of old interfaces that formed in mid-February. There is 60-100 cm sitting on a persistent weak layer that was buried in late January. These interfaces are mostly made up of sugary facets, hard wind pressed snow, surface hoar in wind-sheltered locations, and sun crust on steep solar aspects. 

Terrain and Travel

  • Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
  • Be aware of the potential for large avalanches due to the presence of a persistent slab.
  • Minimize your exposure time below cornices.
  • When a thick, melt-freeze surface crust is present, avalanche activity is unlikely.

Regions covered