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Avalanche Forecast

Archived

Dec 28th, 2023–Dec 29th, 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, Seven Sisters, Howson, Kispiox, Microwave-Sinclair, North Bulkley, South Bulkley, South Bulkley, South Bulkley, Telkwa.

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

Confidence

No Rating

Avalanche Summary

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

Snowpack Summary

15-20 cm of recent snowfall has been blown around forming new 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.Avalanches are currently not a concern below 1100 m elevation as there is not enough snow.

Weather Summary

Thurs Night

Cloudy, 2 cm of snow expected. southeasterly 30 km/h winds. Freezing level up to 1200m and treeline temperatures around -2 °C.

Friday

Cloudy, 1cm of new snow with a chance of freezing rain. Winds 30 km/h easterly, Freezing level up to 1200 m. Treeline high of -2 °C.

Saturday

Cloudy, 5 cm of snow (possibly rain at elevations below 1100 m) expected. 20 km/h southeasterly wind. Freezing level 1250m. Treeline high around -0°C.

Sunday

Mix of sun and cloud, no precipitation. 30 km/h southwest winds. Freezing level falling to 500 m. Treeline high of -5 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

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

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.