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Archived

Avalanche Forecast

Dec 18th, 2023–Dec 19th, 2023
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low

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

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.

Avalanche Problems

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