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Avalanche Forecast

Archived

Dec 29th, 2023–Dec 30th, 2023

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

Regions

Northwest Inland, Howson, Kispiox, Microwave-Sinclair, North Bulkley, South Bulkley, South Bulkley, South Bulkley, Telkwa.

Several weak layers exist in the snowpack and human-triggered avalanches remain possible. Watch for signs of instability such as whumpfing.

Confidence

High

Avalanche Summary

On Thursday a large (size 2.5) naturally triggered wind slab avalanche was reported near Ashman. On Tuesday, a small (size 1) rider-triggered wind slab avalanche was reported in northeast-facing, treeline terrain by Hudson Bay Mountain. Whumpfing has been experienced by backcountry users in the Babines, Grizzly Plateau, and Hudson Bay Mountain recently. The whumpfing has been occurring mainly due to the surface hoar layers described in the snowpack summary.

Snowpack Summary

Recent incremental snowfall has been blown around forming wind slabs on mostly northwest through east-facing slopes at ridgetops. Southerly faces in the alpine are scoured down to the ground or an early-season crust. In most areas, two or more preserved surface hoar layers can be found buried between 35 cm and 80 cm deep. They appear to be most prominent at treeline and below but have been observed in some alpine locations as well.Snowpack depths at treeline are variable across the region with generally deeper amounts (~150cm) in the western part and shallower (~80cm) in the eastern part.The snow surface is likely moist or crusty up to treeline, and below 1100 m there is very little snow.

Weather Summary

Friday Night

Cloudy with 2 cm of snow expected, southeasterly winds 10-20 km/h, freezing level up to 1100m, and treeline temperatures falling to -4 °C.

Saturday

Cloudy with 2-5 cm of new snow, southerly winds 20-30 km/h, freezing level of 1400m and treeline temperatures rising to 1 °C.

Sunday

Mostly cloudy with no precipitation, westerly winds 10-25 km/h, high of -4 at treeline.

Monday

Mostly cloudy with a trace of new snow, variable winds 5-10 km/h, freezing level varies between 800m - 400m, and a high of -3 at treeline.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
  • Watch for wind-loaded pockets especially around ridgecrest and in extreme terrain.

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.

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.