Avalanche forecast

Purcells

Mar 20 – 21, 2025Avalanche Canada
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Avalanche danger

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

Forecast snow and wind are expected to form fresh storm slabs reactive to human triggers.

Watch for rapidly changing conditions during periods of heavy loading from new snow and wind.

Avalanche problems

  • Persistent Slabs

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

    Triggering buried weak layers is most likely in wind-affected terrain on northerly and easterly aspects. Small avalanches in motion may trigger these deeper layers creating very large and destructive avalanches.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2.5

    Forecast snow and wind are expected to form fresh storm slabs reactive to human triggers.

  • Deep Persistent Slabs

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

    There is evidence that weak layers near the bottom of the snowpack are starting to wake up. Explosives and smaller avalanches in motion have both triggered this deep weak layer recently resulting in very large avalanches.

Confidence

Moderate

Avalanche Summary

On Wednesday, numerous explosive triggered persistent slab avalanches up to size 3 on primarily northerly and easterly aspects at treeline and above.

On Tuesday, several explosive triggered deep persistent slab avalanches up to size 3.5 were reported on north and west aspects in the alpine. The weak layer was around 150 cm down.

Snowpack Summary

Forecast snow and wind are expected to form fresh storm slabs reactive to human triggers.

30 - 50 cm of snow overlies a crust on sunny slopes and lower elevations, and surface hoar or facets on sheltered and shady upper elevations.

Several persistent weak layers consisting of a crust, facets, and/or surface hoar from February and January remain a concern. They are down 50 to 100 cm in most areas.

The bottom of the snowpack is composed of large facets in most areas. There is evidence that this layer is becoming reactive again, and some very large avalanches have failed on this layer recently.

Weather Summary

Thursday night

Cloudy with 5 to 15 cm of snow. 10 to 20 km/h south ridgetop winds. Treeline temperature -7 °C. Freezing level valley bottom.

Friday

Cloudy with 10 to 25 cm of snow. 10 to 20 km/h southwest ridgetop winds. Treeline temperature -4 °C. Freezing level 1600 m.

Saturday

Mix of sun and cloud. 10 to 20 km/h west winds. Treeline temperature -5 °C. Freezing level 1500 m.

Sunday

Mostly cloudy. 10 to 20 km/h southwest ridgetop winds. Treeline temperature -1 °C. Freezing level 1900 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Watch for signs of instability like whumpfing, hollow sounds, shooting cracks, or recent avalanches.
  • Watch for rapidly changing conditions during periods of heavy loading from new snow, wind, or rain.
  • Use small, low consequence slopes to test the bond of the new snow.
  • Avoid steep, rocky, and wind-affected areas where triggering slabs is more likely.
  • Be aware of the potential for large, destructive avalanches due to deeply buried weak layers.

Regions covered