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Avalanche Forecast

Archived

Dec 9th, 2022–Dec 10th, 2022

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, Bonnington, Grohman, Kootenay Pass, Norns, Rossland, Ymir.

Continue to make conservative terrain choices. We are inching closer to the tipping point where persistent slab avalanches become more reactive to rider triggering. Read our newest blog to learn more about this concerning layer and how to manage it.

Confidence

Moderate

Avalanche Summary

No significant avalanches were reported in the past couple days. Backcountry users continue to report whumpfing and cracking, especially when traveling at the treeline elevation.

Snowpack Summary

Southerly winds continue to redistribute new snow into wind slabs on west, north and east aspects. Up to 20 of recent snow has buried a layer of surface Hoar in sheltered terrain and a sun crust on south facing slopes.

A concerning layer of surface hoar from mid November is buried down 40 to 60cm. This layer could become more reactive as slab properties above it increase with new snow and wind.

Snowpack depths average 80-160 cm in the alpine. Below treeline elevations are now above the threshold for avalanches in many areas.

Weather Summary

Friday Night

Flurries with 5 to 10cm of new snow expected. Southerly winds increasing throughout the night, strong by early Saturday morning. Low of -7 at 1500m.

Saturday

Cloudy with 10 to 15cm of new snow. Moderate southerly winds in the morning becoming light in the afternoon. High of -2 at 1500

Sunday

Flurries in the morning bringing trace amounts of new snow and then clearing in the afternoon. High of -2 at 1500m. Light easterly winds.

Monday

Mostly cloudy with the possibility of light flurries bringing trace amounts of new snow. Light winds and a high of -9 at 1500m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Fresh snow rests on a problematic persistent slab, don't let good riding lure you into complacency.
  • Storm slab size and sensitivity to triggering will likely increase through the day.
  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Back off if you encounter whumpfing, hollow sounds, or shooting cracks.

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.

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.