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Avalanche Forecast

Archived

Dec 26th, 2023–Dec 27th, 2023

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

North Rockies, Kakwa, McGregor, Pine Pass, Renshaw.

There have been no field observations in the past few days. Submit a MIN if you head out!

Uncertainty around buried weak layers is best managed with conservative terrain choices.

Confidence

Low

Avalanche Summary

There have been very few reports from this region in the past few days.

Over the weekend, there were numerous reports of natural and skier-triggered persistent slabs, mainly at treeline, up to size 2. Check out this MIN from Powder King on Saturday and this MIN in Torpy on Friday. We suspect these avalanches ran on one of the surface hoar layers in the top meter of the snowpack.

Looking forward to Wednesday, buried weak layers continue to be the main concern.

Snowpack Summary

Recent strong winds have created heavily wind-affected surfaces in the alpine and treeline. Below treeline a new crust is on or near the surface.

The mid pack contains several layers of note; a layer of surface hoar and a crust down 20 to 30 cm , a significant crust from the early December rain event down around 50 cm and a layer of surface hoar down 60 to 100 cm.

Snowpack depth throughout this region is highly variable and as a result the depths of the above mentioned layers are approximate and could be different than what you find in your riding area.

Weather Summary

Tuesday Night

Clearing. Southwest alpine wind 80 km/h dropping to 40 km/h. Treeline temperature -5 °C. Freezing level dropping to valley bottom.

Wednesday

A mix of sun and cloud. Southwest alpine wind 40 to 60 km/h. Treeline temperature rising to 0 °C. Freezing level rising to 2500 m in the south, 1500 m in the north.

Thursday

A mix of sun and cloud. Southwest alpine wind 40 to 60 km/h. Treeline temperature 0 °C. Freezing level 1500 m.

Friday

A mix of sun and cloud. South alpine wind 30 to 50 km/h. Treeline temperature 1 °C. Freezing level rising to 2500 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Any steep opening in the trees should be treated as suspect right now.
  • Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
  • Use careful route-finding and stick to moderate slope angles with low consequences.

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.