Dashboard Regions Weather Stations Radar Alerts Glossary
Contact About
Log In

Register for an account and never miss a forecast again!

Register

Avalanche Forecast

Archived

Jan 3rd, 2020–Jan 4th, 2020

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

Regions

Kootenay Boundary.

Storm slab avalanches continue to be triggered in the region. There is also still concern for triggering buried weak layers. Conservative decision-making is essential to manage these avalanche problems.

Confidence

High -

Weather Forecast

FRIDAY NIGHT: Increasing cloud with early-morning flurries, accumulation 2 to 5 cm, moderate to strong southwest wind, alpine temperature -2 C, freezing level 1400 m.

SATURDAY: Mix of sun and cloud with isolated flurries, accumulation 5 to 10 cm, moderate to strong west wind, alpine temperature -9 C, freezing level 1000 m.

SUNDAY: Cloudy with light snowfall, accumulation 2 to 5 cm, moderate southwest wind, alpine temperature -7 C, freezing level 800 m.

MONDAY: Cloudy with light snowfall, accumulation 2 to 5 cm, moderate southwest wind, alpine temperature -8 C, freezing level 700 m.

Avalanche Summary

Many avalanches were reported on Thursday of large storm slab avalanches, being triggered naturally and by humans. They have generally been 20 to 50 cm deep and occurring at treeline and alpine elevations. Two large avalanches occurred on the deeply buried weak layers described in the snowpack summary, indicating that they can still be triggered.

Snowpack Summary

Around 40 to 60 cm of recent storm snow has bonded to form a touchy storm slab problem. The snow has been redistributed by strong southwest wind, loading lee features near ridges. The storm snow overlies a weak layer of feathery surface hoar and a hard melt-freeze crust on sun-exposed aspects, which has increased the reactivity of these slabs. 

There are multiple weak layers buried around 80 to 120 cm deep, including two more surface hoar layers and weak faceted snow near the bottom of of the snowpack. This fundamentally unstable snowpack structure remains a concern. It is possible that storm slab avalanches could step down to these deeper layers or the layers could be triggered in areas where the snowpack is thin, forming large and destructive avalanches.

Terrain and Travel

  • Make conservative terrain choices and avoid overhead hazard.
  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Be aware of the potential for large avalanches due to the presence of buried surface hoar.
  • Storm slabs in motion may step down to deeper layers resulting in large avalanches.

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

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.