Avalanche forecast

Purcells

Apr 18 – 19, 2019Avalanche Canada
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Archived · expired 7 years ago

Avalanche danger

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

Highlights

Conditions will vary rapidly with elevation. Watch for loose wet activity below the rain-snow line and touchy wind slabs above. Travel conservatively during Friday's stormy conditions.

Avalanche problems

  • Wind Slabs

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

    Snow depth will change dramatically due to a variable freezing level. Expect touchy slabs above the rain-snow line, somewhere between 2000 m and 2500 m. Use particular caution in lee features near ridges where deposits will be the deepest.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2

    The likelihood of loose wet avalanche activity should increase due to rain, particularly where it falls on previously dry snow. Best to avoid steep slopes during and after periods of rain.

Snowpack Summary

The freezing level rose to around 2500 m on Thursday, moistening the snowpack on all aspects. Above 2500 m, around 10 to 20 cm of snow may accumulate on Thursday night, with rain below. Another 5 to 15 cm of snow may accumulate above around 1800 m to 2200 m on Friday. Where the precipitation falls as snow, it may form touchy slabs on Friday, particularly in exposed areas due to strong southwest wind.

Weak and sugary faceted grains may remain at the bottom of the snowpack in the alpine, producing a low likelihood but high consequence scenario. Steep, rocky areas with a shallow snowpack are the most likely places to trigger this layer.

Confidence

Moderate - Freezing levels are uncertain

Weather Forecast

THURSDAY NIGHT: Cloudy with rain, accumulation 10 to 20 mm, moderate to strong southwest wind, alpine temperature 1 C, freezing level 2500 m.

FRIDAY: Cloudy with alpine snow, accumulation 5 to 15 cm, moderate west wind, alpine temperature -1 C, freezing level 2200 m dropping to 1800 m.

SATURDAY: Mix of sun and clouds with isolated flurries, light north wind, alpine temperature -3 C, freezing level 2000 m.

SUNDAY: Mostly clear skies, light south wind, alpine temperature -3 C, freezing level 2100 m.

Avalanche Summary

Small (size 1) storm slab avalanches were triggered naturally and by a skier on Wednesday. They were in alpine terrain, 20 to 30 cm deep, and on north to east aspects.

Regions covered