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Avalanche Forecast

Archived

Jan 9th, 2021–Jan 11th, 2021

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

Regions

North Rockies.

While the snowpack is slowly gaining strength in many locations, Pine Pass remains weaker than other locales. Wherever you go, watch for potentially deep wind slabs in exposed terrain and stay away from cornices. The best & safest riding will be found out of the wind.

Confidence

Moderate - Uncertainty is due to extremely variable snowpack conditions reported through the region.

Weather Forecast

Warming temperatures and quite a bit of west/southwest wind are in store.

SATURDAY NIGHT: Freezing level at valley bottom, strong southwest wind, trace of snow possible. 

SUNDAY: Broken cloud cover at dawn with clear skies by lunch, freezing level beginning at valley bottom steadily climbing throughout the day to about 1400 m by sunset, strong southwest wind, trace of snow possible. 

MONDAY: Scattered cloud cover, freezing level starting at valley bottom rising to about 1500 m during the day, strong to extreme southwest wind, trace of snow possible.

TUESDAY: Broken cloud cover, freezing level starting at valley bottom rising to about 1800 m during the day, strong to extreme southwest wind, 5 to 10 cm of snow at upper elevations with rain in the valleys.

Avalanche Summary

Several size 1 to size 2.5 natural avalanches were observed on north, northeast and east facing slopes in the alpine around the Bullmoose area near Tumbler Ridge Friday, more details in this MIN report.  

Our field team found some recent avalanche activity in the Pine Pass on Thursday in the Bijoux area, more details here. Recent wind slabs to size 1.5 were reported from the Kakwa Saturday.

Snowpack Summary

The last storm was pretty warm, and you're likely to find a crust on or just below the surface up to about 1200 m.

80 to 90 cm of snow rests above a weak layer buried in early December which has created a persistent slab avalanche problem and a low probability/high consequence scenario. Depending on location, the buried weak layer is composed of surface hoar and/or a crust/facet combination.

This interface remains active and problematic at Pine Pass, but elsewhere it's gaining strength. It's presence is spotty in the McGregors and Tumbler Ridge, recent testing on this interface near Tumbler did not produce any results. This problem has not been found at Renshaw, but has been found in the surrounding areas near McBride. There is very little information coming out of the Kakwa right now, but preliminary information suggests it may not be a player there, at least not yet.

Total snow depths are 150-300 cm around Pine Pass & the McGregors. Near McBride there is 150 to 200 cm, around Tumbler 50 to 200 cm can be found. 

Terrain and Travel

  • Expect slab conditions to change drastically as you move into wind exposed terrain.
  • Be aware of highly variable recent wind loading patterns.
  • Surface hoar distribution is highly variable. Avoid generalizing your observations.

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.