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Avalanche Forecast

Archived

Dec 25th, 2024–Dec 26th, 2024

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

Regions

West Island.

The storm will rage on after an expected large natural avalanche cycle Wednesday night. Continue avoiding avalanche terrain while the new snow settles and stabilizes.

Confidence

Moderate

Avalanche Summary

No new avalanches have been reported, however visibility into much of the Island's avalanche terrain is very limited.

It is expected that a large natural avalanche cycle will be ongoing through Wednesday night. Human-triggering potential will likely persist as natural avalanches taper off.

Snowpack Summary

By Thursday morning, 40 - 100 cm of new snow should have accumulated across the Island, with the greatest accumulations on the west coast. Fluctuating freezing levels are likely to form distinct layering and mid-storm failure planes as new snow accumulates.

The new snow is falling on 20 - 30 cm of older, settled snow sitting on the early December crust, or on a combination of wet grains or crust at lower elevations. Below this, the remainder of the snowpack is thoroughly settled and bonded as a result of recent heavy rain.

Snowpack depths at treeline in advance of the storm varied from about 100 -150 cm on the north and south island, closer to 200 to 250 cm on the central island.

Weather Summary

Wednesday night

Cloudy with 10-60 mm of mixed precipitation with the greatest values on the west island. 50 to 70 km/h south ridgetop wind. Freezing level reaching 1500 m.

Thursday

Cloudy with wet flurries bringing 5 to 15 cm of new snow after uncertain overnight accumulations from mixed precipitation. 50 to 70 km/h southeast ridgetop wind shifting southwest. Freezing level 1200 m.

Friday

Mainly cloudy with flurries bringing less than 5 cm of new snow, increasing overnight. 20 to 30 km/h southeast ridgetop wind. Freezing level 1300 m.

Saturday

Cloudy with continuing wet flurries bringing 5 to 30 cm of new snow. 50 to 60 km/h southwest ridgetop wind. Freezing level 1400 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Be aware of the potential for human triggerable storm slabs at lower elevations, even on small features.
  • Continue to make conservative terrain choices while the storm snow settles and stabilizes.

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.