Avalanche Forecast

Issued: Dec 18th, 2023 4:00PM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Persistent Slabs.

Avalanche Canada isnowsell, Avalanche Canada

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Buried surface hoar remains the primary avalanche concern, currently at an ideal depth for potential human triggering.

Summary

Confidence

Moderate

Avalanche Summary

Sporadic reports continue to provide evidence that buried surface hoar layers remain human-triggerable. They have mostly occurred in treeline and alpine terrain, but have been reported as low as 1950 m.

This Mountain Information Network (MIN) post from neighboring Glacier National Park is the most recent occurrence.

Snowpack Summary

Up to 30 cm of well-settled recent snow sits over a variety of snow surfaces, including crusts on south-facing terrain and surface hoar in wind-sheltered features.

A concerning layer of surface hoar is now roughly 50-80 cm below the surface. This layer has recently been reactive to human triggering above 1900 m.

The lower snowpack is generally faceted but shows signs of strengthening and rounding. A hard crust may be found near the ground.

Average treeline snowpack depths are around 80-120 cm. Snowpack tapers rapidly as you move lower in elevation.

Weather Summary

Monday Night

Mostly cloudy with trace amounts of snow, southeast alpine winds 20 to 40 km/h, treeline temperature -4 °C.

Tuesday

Cloudy with trace amounts of snow, southeast alpine winds 20 to 40 km/h, treeline temperature -2 °C.

Wednesday

Cloudy with trace amounts of snow, southwest alpine winds 20 to 40 km/h, treeline temperature -2 °C.

Thursday

Cloudy with 2 to 8 cm of snow, southwest alpine winds 40 to 50 km/h, treeline temperature -2 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Uncertainty is best managed through conservative terrain choices at this time.
  • Remote triggering is a concern, watch out for adjacent and overhead slopes.
  • Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.

Problems

Persistent Slabs

An icon showing Persistent Slabs

A persistent weak layer of surface hoar is down 50-80 cm in the snowpack. Large, human triggered avalanches have occurred over the past few days at treeline and above.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1.5 - 2.5

Valid until: Dec 19th, 2023 4:00PM

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