Avalanche Forecast

Issued: Feb 23rd, 2021 4:00PM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is moderate. Known problems include Storm Slabs.

Avalanche Canada ahanna, Avalanche Canada

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Ease into terrain cautiously on Wednesday. Start small and look for signs of instability like shooting cracks and recent avalanches. Be mindful that sunshine can have a powerful effect on stability - and your desire to push into aggressive terrain.

Summary

Confidence

Moderate - Recent weather patterns have resulted in a high degree of snowpack variability within the region. Uncertainty is due to how quickly the snowpack will recover and gain strength.

Weather Forecast

TUESDAY NIGHT: Partly cloudy, light northwest wind, freezing level valley bottom.

WEDNESDAY: Sunny, light westerly wind increasing in the evening, freezing level 800 m.

THURSDAY: 5-15 cm of new snow, strong southwest overnight wind easing to moderate, freezing level 1200 m.

FRIDAY: 5-15 cm of new snow, light northwest wind, freezing level 500 m.

Avalanche Summary

The Selkirks (eastern ranges of the region) were the hotspot for storm activity this cycle, with widespread natural wind and storm slab avalanches size 2-3 and explosive triggered size 3-4, many running to valley bottom. Activity was ongoing as of Monday night in neighboring Glacier National Park.

Reports from the Monashees indicate a natural cycle of size 2 storm slabs peaking over the weekend and becoming more stubborn to human triggers as the storm tapered.

We've had no reports of storm avalanche activity stepping down to persistent layers.

Snowpack Summary

40-80 cm of recent snow has been blown around by strong to extreme westerly winds, forming thick slabs in lee features at upper elevations.

The recent snow sits on old, facetted and/or extensively wind affected snow that sat on the surface during the extended cold, windy drought period. There is uncertainty around how long it will take for this interface to bond but reports from the Monashees have indicated a positive trend already.

We've now got 70 to 120 cm of snow above the late January persistent weak layer which is composed of surface hoar in openings in the trees and/ or a crust on steep solar aspects. An absence of step-downs to this layer in the most recent storm cycle indicate that is has likely healed.

Terrain and Travel

  • Don't be too cavalier with decision making, storm slabs may remain sensitive to human triggering.
  • Start with simple well supported terrain below treeline and gather information before stepping out.
  • Avoid slopes when the solar radiation is strong, especially if they have large cornices overhead.

Problems

Storm Slabs

An icon showing Storm Slabs

40-80 cm of recent storm sits overtop a thick layer of weak, sugary facets. In the Monashees, this interface appears to be bonding well, while reactivity may persist longer in the Selkirks. Human triggering is most likely in wind loaded features.

Cornices have likely experienced rapid growth with recent strong westerly winds. Fresh, unsupported tabs may weaken in the sun Wednesday. Tabs that break off can act as triggers on slopes below.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Feb 24th, 2021 4:00PM

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