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Avalanche Forecast

Archived

Jan 18th, 2022–Jan 19th, 2022

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.
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

South Rockies.

Riding conditions are improving with new fresh snow. Take time to read about the various forecasted avalanches problems before heading into avalanche terrain. 

Confidence

High - Confidence is due to a stable weather pattern with little change expected.

Weather Forecast

TUESDAY NIGHT: Partly cloudy, treeline high around -10 C, light variable wind, freezing level at valley bottom.

WEDNESDAY: Sunny periods, treeline high around -12 C, light westerly wind, freezing level at valley bottom.

THURSDAY: Flurries, treeline high around -5 C, strong southwesterly wind, freezing level rising to 1500 m.

FRIDAY: A mix of sun and clouds, treeline high around -5 C, light southwesterly wind, freezing level rising to 1500 m.

Avalanche Summary

Several small loose-dry avalanches (size 1) were observed on steep terrain near Mear Lake Tuesday. They released naturally in 20-25 cm of powder snow.

Recent deep persistent slab avalanches were reported in neighbouring regions (Lizard-Flathead and Waterton National Park) over the last few days. These human-triggered and natural avalanches failed on the early December crust and showed wide propagation. This evidence suggests the deep persistent slab problem is still a concern in the region. 

Snowpack Summary

The region received between 10-25 cm of fresh dry snow Tuesday, which now overlies older surfaces like hard wind slabs or recent melt-freeze crust. The crust varies from thin/breakable to thick/supportive, according to the aspects and elevation. Under it, the snowpack consists of a variety of old surfaces, including soft snow in sheltered areas and wind slabs in exposed and open areas. 

The most notable layer of concern in the snowpack is a crust that was formed in early December and is now typically down 80-150 cm. In the neighbouring Lizard-Flathead region, three very large avalanches were reported on this layer on Jan 13. This layer has created a tricky low likelihood, high consequence scenario which is best managed through conservative terrain choices and disciplined backcountry travel techniques.

Terrain and Travel

  • Investigate the bond of the recent snow before committing to your line.
  • Wind slabs may be poorly bonded to the underlying crust.
  • Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
  • Be aware of the potential for large avalanches due to the presence of a persistent slab.

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.

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.