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Avalanche Forecast

Archived

Feb 5th, 2023–Feb 6th, 2023

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

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

Evaluate snow conditions as you transition into open terrain features, and be on the lookout for signs of instability like shooting cracks. Stiff, wind deposited snow can be expected to avalanche under the weight of a rider. Also, moist, heavy snow may slide easily on steep slopes. Especially where it is sitting on top of lighter, fluffy snow.

Confidence

Moderate

Avalanche Summary

On Saturday, east of Fernie, a couple of small to large natural and rider triggered avalanches were reported that involved cornices. See the MIN report for more information.

Natural and rider-triggered (size 1 to 1.5) wind slabs have been recently reported at treeline and alpine elevations. This MIN report from the South Rockies field team is a good example of terrain where wind slabs are more likely to be triggered.

Looking forward, riders could trigger small wind slabs in lee terrain features from the recent snow and sustained southwest wind.

Please continue to share any observations or photos on the Mountain Information Network.

Snowpack Summary

Possible 5-10 cm of moist snow on the surface.

10 to 15 cm of storm snow from late last week was redistributed by moderate to strong winds which developed wind slabs at treeline and alpine elevations. This overlies previous wind slabs that may still be reactive, or a melt-freeze crust below 1900 m

The mid-pack is consolidated in the Lizard Range with a robust melt-freeze buried 70 to 90 cm.

Outside of the Lizard Range, the snowpack is shallower and more faceted. In these areas, deep weak layers formed early season are slowly gaining strength but are still a concern, especially in steep rocky terrain features.

Weather Summary

Sunday Night

Clearing overnight. No new snow expected. Moderate northwest ridgetop wind. Treeline temperature around -3 ºC.

Monday

Clear in the morning, increasing clouds through the day. No new snow expected. Moderate southwest ridgetop wind, trending to strong at higher elevations. Treeline temperature around -2 ºC.

Tuesday

Cloudy. 5-12 cm of snow expected, on the higher end in the north of the region. Moderate southwest ridgetop wind, trending to strong at higher elevations. Treeline temperature around -5 ºC.

Wednesday

Mostly cloudy. 5-15 cm of snow expected, on the higher end in the south of the region. Moderate west ridgetop wind. Treeline temperature around -7 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Approach lee and cross-loaded slopes with caution.
  • Be careful with wind slabs, especially in steep, unsupported and/or convex terrain features.
  • Watch for unstable snow on specific terrain features, especially when the snow is moist or wet.
  • Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.

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.