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Avalanche Forecast

Archived

Feb 17th, 2022–Feb 18th, 2022

Alpine
Natural avalanches unlikely.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.

Regions

Purcells.

Heightened avalanche conditions exist on open convex slopes. Avalanches are less likely where thick crusts exist near the surface.

Confidence

High - We have a good understanding of the snowpack structure and confidence in the weather forecast

Weather Forecast

THURSDAY NIGHT: Cloudy skies with isolated flurries bringing trace amounts of snow (and up to 5 cm along the western Purcells), moderate to strong wind from the northwest, treeline temperatures around -6 C.

FRIDAY: Cloudy with isolated flurries bringing up to 5 cm of snow, moderate wind from the west, treeline temperatures around -4 C with freezing level around 1500 m.

SATURDAY: Cloudy with flurries bringing 5-15 cm of snow by the evening, moderate to strong wind from the southwest, treeline temperatures around -6 C.

SUNDAY: Partly cloudy with scattered flurries bringing another 5-10 cm of snow, light wind from the northwest, treeline temperatures drop to -10 C throughout the day.

Avalanche Summary

No significant human triggered avalanches have been reported over the past week. Explosive cornice control over the past few days has not resulted in avalanches on the slopes below, except for one on Sunday when a cornice fall triggered a size 2.5 slab west of Forster Creek. This avalanche occurred on north aspect at 2250 m and failed on a 40 cm deep surface hoar layer.

Snowpack Summary

5 to 15 cm of fresh snow sits above hard wind-affect snow and melt-freeze crusts in most terrain. The exception could be north-facing terrain at treeline where there may still be soft snow. North-facing treeline terrain also has a 20 to 40 cm deep surface hoar layer that was buried at the end of January. This layer has produced variable results in recent snowpack tests, and could still be reactive on some steep convexities. The lower snowpack is well consolidated, with a crust/facet layer found 80 to 150 cm deep. This layer is currently considered dormant, but could become active later this season as discussed in this forecaster blog.

Terrain and Travel

  • Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
  • Look for signs of instability: whumphing, hollow sounds, shooting cracks, and recent avalanches.
  • Pay attention to isolated alpine features as well as cross-loaded features at treeline.

Problems

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.