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Avalanche Forecast

Archived

Dec 29th, 2023–Dec 30th, 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

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

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 week.

Last 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.

Natural avalanche activity is not expected. However, human-triggering of wind slabs remain possible.

Snowpack Summary

Recent winds have resulted in extensive wind-affected surfaces in the alpine and treeline. Below treeline, a fresh crust has formed either on or close to the surface.

The mid pack contains several layers of note; a layer of surface hoar down 30 to 50 cm, a significant crust from the early December rain event down around 60 cm and a layer of surface hoar down 70 to 120 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

Friday Night

Partially cloudy, no new snow. South alpine wind 40 to 50 km/h. Treeline temperature 3 °C. Freezing level 2500 m. above freezing temperatures in the alpine

Saturday

Cloudy with periods of sun. No new snow. South alpine wind, 20 to 40 km/h. Treeline temperature 1 °C. Freezing level 2000 m. above freezing temperatures in the alpine

Sunday

Cloudy, snow flurries 1-5 cm. South alpine wind, 20 to 40 km/h. Treeline temperature -5 °C. Freezing level 1000 m.

Monday

Cloudy, snow flurries 1-5 cm. South alpine wind, 20 to 40 km/h. Treeline temperature -5 °C. Freezing level 1000 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Minimize exposure to steep planar south-facing slopes - especially if they see sunshine.
  • 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

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.