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Avalanche Forecast

Archived

Dec 13th, 2022–Dec 14th, 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 continue to receive reports of large natural and human-triggered avalanches on the persistent weak layer. Keep your terrain choices conservative and be prepared to back off quickly if you find signs of instability; whumpfing and shooting cracks.

Read our featured blog to learn more about how to manage a persistent slab problem when traveling in the backcountry.

Confidence

Moderate

Avalanche Summary

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.

Evidence of several natural storm slab avalanches was observed to have released on the Dec 5 weak layer. A few natural persistent slab avalanches, size 2.5, were reported to have released or 'stepped down' from smaller avalanches onto deeper instabilities.

Explosive control triggered several persistent slab avalanches up to size 3 in the eastern part of the region.

Snowpack Summary

Small surface hoar is forming on 40 - 50 cm of settling storm snow. On south-facing slopes snow sits on a sun crust and in sheltered terrain it overlies a weak layer of 5mm surface hoar. In the alpine northerly winds are redistributing available snow into deep pockets in lees.

Buried 60 to 90cm deep, a persistent layer of surface hoar, crust, and faceted crystals is the primary concern within the snowpack. 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.

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

Weather Summary

Tuesday Night

Mainly cloudy, isolated flurries trace accumulation. Northerly ridge wind 20 - 40 km/hr. Alpine temperatures, low of -10. Freezing levels valley bottom.

Wednesday

Sunny with cloudy periods. Northerly ridge wind 30 - 50 km/hr. Alpine temperatures, high of -8. Freezing levels valley bottom.

Thursday

Partly cloudy skies. Northwesterly ridge winds 40 - 60 km/hr. Alpine temperatures, high of -8. Freezing levels valley bottom.

Friday

Partly cloudy skies. Northwesterly ridge winds 40 - 60 km/hr. Alpine temperatures, high of -8. Freezing levels valley bottom.

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.
  • Give the new snow several days to settle and stabilize before pushing into bigger terrain.
  • Avoid open slopes and convex rolls below treeline where weak layers may be preserved.
  • Be carefull around freshly wind loaded features.

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.