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 4th, 2021–Jan 5th, 2021

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

Recently formed storm slabs will be most reactive in wind affected areas at upper elevations and human triggering in these areas is likely. Be especially cautious as you transition into wind affected terrain. 

Confidence

Moderate - Uncertainty is due to whether buried persistent weak layers become active, triggering avalanches, with the arrival of the forecast weather.

Weather Forecast

Monday night: Snow, 5-10 cm, moderate to strong south wind, freezing level 500 m.

Tuesday: Sun and cloud, moderate southwest wind, alpine high -7, freezing level 800 m.

Wednesday: Snow, 5-15 cm, moderate southwest wind easing, alpine high -4, freezing level 1200 m.

Thursday: Snow, 5-10 cm, light northwest wind, alpine high -5, freezing level 1100 m.

Avalanche Summary

Numerous natural, human and explosive triggered storm slabs size 1-2.5 were reported on Saturday and Sunday. Check out this avalanche triggered remotely by a skier in Kootenay Pass on the weekend.

Sporadic reports of persistent slab avalanches have been popping up, including a natural size 3 near Whitewater on Sunday. With new snow slowly but steadily piling up, the chances of a resurgence of persistent slab avalanches will increase. This incremental loading makes it difficult to predict when the tipping point will be reached. The uncertainty around this problem is best managed with conservative terrain selection.

Snowpack Summary

30-60 cm of recent storm snow has seen significant wind affect at upper elevations. In sheltered areas, the recent snow may sit over surface hoar.

Two weak layers are buried in close proximity to one another. They are 70-100 cm deep around Nelson and 50-80 cm deep around Rossland and other western parts of the region. The layers are composed of feathery surface hoar and sugary faceted grains and they overlie a hard melt-freeze crust. 

Terrain and Travel

  • Continue to make conservative terrain choices while the storm snow settles and stabilizes.
  • Keep in mind that human triggering potential persists as natural avalanching tapers off.
  • Be especially cautious as you transition into wind affected terrain.
  • Be aware of the potential for large avalanches due to the presence of buried persistent weak layers.

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.