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Avalanche Forecast

Archived

Dec 30th, 2022–Dec 31st, 2022

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

Regions

Lizard-Flathead, South Rockies, Flathead, Lizard, Bull, Elkford East, Elkford West.

The snowpack is slowly gaining strength, but triggering large persistent slab avalanches remains possible. Approach avalanche terrain with caution and stick to smaller pieces of terrain.

Confidence

Moderate

Avalanche Summary

A natural cycle of large and very large avalanches (size 2 to 3) occurred earlier this week, and explosive control has continued to produce large avalanches as recently as Friday. Most of the avalanches were in storm snow layers, however some are suspected to have stepped down to deeper weak layers, especially those in the Sparwood and Elkford areas. We suspect it is becoming more difficult to trigger storm and persistent slab avalanches, however caution should be taken in challenging or complex terrain given the uncertainty and consequence of these large avalanches.

Snowpack Summary

A dusting of new snow is falling on top of settled snow from the December 26th storm. This storm left roughly 50 cm of heavy snow above a rain crust that extends to treeline elevations. While the recent snow has shown signs of settling and strengthening, there are two deeper layers of concern that may still be possible to trigger in specific terrain. This includes a 40 to 80 cm deep layer of surface hoar and facets that was buried in mid-December and an 80 to 150 cm deep layer of surface hoar and facets that was buried in mid-November. These layers are at the deeper end of these ranges in Lizard Range and Fernie areas and the shallower end of the range towards Sparwood and Elkford. The persistent slab above these layers may be easier to trigger around Sparwood and Elkford, because they are closer to the surface.

Weather Summary

Friday night

Light snowfall with 5 to 10 cm in the Lizard range and a trace to 5 cm elsewhere, 30 to 40 km/h wind from the southwest, treeline temperatures around -5 °C.

Saturday

Cloudy with light snowfall and localized accumulations up to 5 cm, 30 to 40 km/h wind from the southwest, treeline temperatures around -5 °C.

Sunday

Partly cloudy with sunny breaks in the afternoon, no precipitation, 20 to 30 km/h wind from the west, treeline temperatures around -7 °C.

Monday

Mix of sun and cloud, no precipitation, light wind, treeline temperatures around -9 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
  • Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
  • Back off if you encounter whumpfing, hollow sounds, or shooting cracks.

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.