Avalanche Forecast

Archived

Jan 9th, 2024–Jan 10th, 2024

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, Ningunsaw, Ningunsaw, Ningunsaw, North Bulkley, South Bulkley, South Bulkley, South Bulkley, Telkwa.

Seek out sheltered terrain and use caution on steep, open slopes where buried weak layers may exist.

Days are short and temperatures are cold; read this blog on managing cold weather.

Confidence

Moderate

Avalanche Summary

On Tuesday and Saturday near Kispiox, several size 1 to 1.5 persistent slabs were triggered by machines. These avalanches mainly occurred at treeline and are suspected to have failed on a weak layer of surface hoar.

Last week, backcountry users experienced whumpfs in the Babines, Grizzly Plateau & Hudson Bay Mountain.

These avalanches and the whumpfing suggest that humans can still trigger avalanches where these layers remain intact.

Snowpack Summary

20 to 40 cm of soft snow exists in areas sheltered from the wind. At upper elevations and exposed areas, this snow could be wind-affected by previous winds. Below 1500 m, new snow overlies a melt-freeze crust.

Two or more preserved surface hoar layers can be found buried between 40 cm and 80 cm deep. These layers are most prominent at treeline and below treeline elevations above 1200 m, but they've also been observed in some alpine locations.

Near Ningunsaw, there may be a crust 100 cm deep that could act as a weak layer.

Snowpack depths at treeline vary across the region with generally deeper amounts (~150 cm) in the west and shallower (~80 cm) in the east.

Weather Summary

Tuesday Night

Clear periods with no new snow. Alpine wind northwest 15 to 40 km/h. Treeline temperatures drop to -15 ºC.

Wednesday

A mix of sun and cloud with isolated flurries. Alpine wind northwest 20 to 40 km/h. Treeline temperatures drop to -25 ºC.

Thursday

Mainly sunny with no new snow. Northerly outflow wind 40 to 60 km/h. Treeline temperatures drop to -30 ºC.

Friday

Sunny with no new snow. Northeast outflow winds easing 20 to 50 km/h. Treeline temperatures around -30 ºC.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Approach steep open slopes at and below treeline cautiously, buried surface hoar may exist.
Look for signs of instability: whumphing, hollow sounds, shooting cracks, and recent avalanches.
Watch for newly formed and reactive wind slabs as you transition into wind affected 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.