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Avalanche Forecast

Archived

Feb 15th, 2023–Feb 16th, 2023

Alpine
Natural avalanches possible, human triggered probable.
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, Kispiox, Microwave-Sinclair, Ningunsaw, South Bulkley, South Bulkley, Telkwa.

Carefully assess for wind slab as you move through terrain. Be especially cautious in shallow snowpack areas.

Confidence

Moderate

Avalanche Summary

Numerous storm and wind slabs were triggered by explosives on Monday within the weekend's storm snow. There was also evidence of a large (size 3) naturally-triggered avalanche in a shallow snowpack area north of Smithers and east of Hazelton. It occurred at 1750 m on a northerly aspect in a cross-loaded terrain feature and stepped down to basal facets.

Looking ahead, riders could still trigger wind slabs in lee terrain features as they slowly bond to the snowpack. There is also a possibility of triggering deeper layers described in the Snowpack Summary.

Snowpack Summary

Variable snowfall amounts accumulated across the region over the weekend but most areas received around 20 cm with strong southwest wind. The wind scoured exposed terrain and formed wind slabs in lee terrain features. A sun crust can be found under this recent snow and a new but small layer of surface hoar can also be found just below the surface.

A melt-freeze crust is found about 80 cm deep. Weak faceted grains may be associated with it in shallow snowpack areas. This layer may have been the culprit for a large avalanche within the past week north of Smithers in a shallow snowpack terrain feature.

An old surface hoar layer from early January may be found about 100 to 150 cm, but there hasn't been any recent avalanche observations on it.

Weather Summary

Wednesday Night

Cloudy with a few centimeters of new snow expected. Light to moderate southwest wind and a low of -5 at 1500m.

Thursday

Cloudy in the morning, clearing around noon. No new snow expected. Light to moderate westerly wind and a high of -6 at 1500m.

Friday

Cloudy with up to 5cm of new snow expected. Moderate westerly winds and a high of -5 at 1500m.

Saturday

Cloudy with light flurries bringing a trace of new snow. Moderate northwest winds and a high of -4 at 1500m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
  • Avoid areas with a thin or variable snowpack.

Problems

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.

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.