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Avalanche Forecast

Archived

Dec 14th, 2022–Dec 15th, 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

North Columbia, South Columbia, Blue River, Esplanade, Jordan, North Monashee, North Selkirk, West Purcell, Badshot-Battle, Central Selkirk, Goat, Gold, Whatshan.

We now have two concerning persistent weak layers within our snowpack.

Be aware that if triggered, avalanches may step down to deeper layers resulting in large, destructive avalanches. Use extra caution at treeline where weak layers are more prominent and be prepared to back off quickly if you find signs of instability like whumpfing and shooting cracks.

Confidence

Moderate

Avalanche Summary

On Tuesday in the northern Monashees, a vehicle remote-triggered a size 2.5 persistent slab avalanche on the mid-November layer. Explosives control produced several size 3 and a size 3.5 persistent slab avalanches.

On Monday, a pair of size 2 human-triggered avalanches were reported in the RMR backcountry. These included a skier accidental and a skier remote from 50 m away on the mid-November layer.

Several natural storm slab avalanches were reported, up to size 2, every day this week. Several natural persistent slab avalanches, up to size 3, were also reported. These larger avalanches may have been triggered by solar warming in the afternoons and released or 'stepped down' from smaller avalanches onto deeper instabilities.

Friday

Snowpack Summary

Snowpack depths are highly variable and range from 90cm at treeline to 200cm in the alpine in wind-affected locations.

Surface: 5 - 8mm surface hoar has formed in sheltered areas on the surface of the snowpack. A sun crust is found on steep solar slopes above 2000m. Northerly winds are creating wind slabs in lees and cross-loading features at higher elevations.

Upper-pack: A 40 - 50 cm soft slab overlies a weak layer of 5 mm surface hoar in sheltered and shaded terrain and a sun crust on sunny south-facing slopes.

Mid-pack: Buried 60 to 90cm deep, is a persistent weak layer of surface hoar, crust, and faceted crystals. This layer has been most reactive at treeline between 1700-2200 m, but it was also observed as low as 1450 m and on all aspects.

Lower-pack: Below the mid-November layer is a generally weak, faceted snowpack.

Weather Summary

Wednesday Night

Partly cloudy skies. Northerly ridge wind 20 km/h gusting to 40 km/hr. Alpine temperatures, high of -10. Freezing levels valley bottom.

Thursday

Partly cloudy skies. Northerly ridge winds 20-30 km/h gusting to 40 km/hr. Alpine temperatures, high of -8. Freezing levels valley bottom.

Friday

Partly cloudy skies. Isolated flurries Friday evening in the northern Selkirks, trace accumulation. Northwesterly ridge winds 30 - 40 km/h, gusting to 60 km/h in the Monashees. Possible alpine inversion, temperatures reach a high of -6. Freezing levels valley bottom.

Saturday

Cloudy skies. Light flurries, 2 cm accumulation. Northeasterly ridge winds 30 km/h.  Alpine temperatures, high of -9. Freezing levels valley bottom.

Saturday

 

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Be aware of the potential for large, destructive avalanches due to the presence of deeply buried weak layers.
  • Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.
  • Minimize exposure during periods of heavy loading from new snow and wind.

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.