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Avalanche Forecast

Archived

Jan 9th, 2023–Jan 10th, 2023

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

Regions

Banff Yoho Kootenay, Banff, East Side 93N, Kootenay, Lake Louise, LLSA, Sunshine, West Side 93N, Field.

The benign weather over the last week has decreased natural avalanche activity and is making explosive triggering more difficult. However, the snowpack is still weaker than normal and forecasters don't have a lot of faith in the current snowpack.

Continued discipline in sticking to mellower terrain with low consequences is the most reliable method of reducing risk in these conditions.

Confidence

Moderate

Avalanche Summary

No new natural avalanches were reported or observed over the last few days. Local ski hills are still triggering both the persistent and deep persistent weak layers but it is taking larger explosives and they are getting fewer and smaller avalanches than last week.

Snowpack Summary

Some wind-affected snow on alpine and treeline ridgetops. 10-20 cm of softer surface snow sits over a denser mid-pack which has formed a slab over the weak facet layers below. The December 17 persistent layer of surface hoar/facets is down 25-60 cm and becoming less reactive. The November 16 deep persistent layer of facets, depth hoar, and/or sun crusts is found near the base of the snowpack with test results continuing to show sudden failures.

Weather Summary

A relatively benign few days before a windy system moves in on Thurs/Friday.

Tuesday: Partly cloudy skies with a few flurries. Treeline temperatures in the -5 to -10 range. Light SW alpine winds.

Wednesday: Clearing skies. Treeline temperatures starting ~ -15 and rising to -5. Light NE alpine winds.

Thursday: Increasing cloud with light flurries. Treeline temperatures starting ~ -15 and rising to -5. Alpin winds increasing to strong to extreme from the SW.

Terrain and Travel Advice

  • Uncertainty is best managed through conservative terrain choices at this time.
  • Use careful route-finding and stick to moderate slope angles with low consequences.

Problems

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.

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.