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Avalanche Forecast

Dec 20th, 2024–Dec 21st, 2024
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
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
3: Considerable
The avalanche danger rating in the alpine will be considerable
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

Regions: Glacier.

The most recent storm snow still needs time to settle. Be especially cautious moving into steep wind effected terrain in the alpine.

Confidence

Moderate

Avalanche Summary

Several natural avalanches were observed in the highway corridor due to a wind spike overnight into Friday. Naturals ran up to size 3 with some running running full feature.

Avalanche control at Rogers Pass on Wednesday produced storm slab avalanches to size 3.

Snowpack Summary

15cm of new snow has fallen with strong gusting Southerly winds. This lands on a series of storm layers from the last week. A persistent weak layer is down 60-90cm. This interface consists of surface hoar in sheltered locations, a sun crust on solar aspects, and continues to produce moderate-hard sudden results in test profiles. The snowpack's base is comprised of several early-season melt-freeze rain crusts.

Weather Summary

Remnants of Saturdays coastal system will push into southern interior bringing a pattern of light snow & flurries overnight into the work week.

Tonight: Trace, Alp low -3°C, Mod-Strong SW wind, Freezing level (FZL) 1700m

Sat: 6cm. Alp High 1°C, Strong SW winds, FZL 1900m

Sun: Trace precip, Alp High -4°C, Moderate SW wind, FZL 1400m.

Mon: 4cm, Alp High -4°C, Moderate SW wind, FZL 1400m

Terrain and Travel Advice

  • Storm slabs in motion may step down to deeper layers resulting in large avalanches.
  • Look for signs of instability: whumphing, hollow sounds, shooting cracks, and recent avalanches.

Avalanche Problems

Storm Slabs

Recent new snow, accompanied by strong SW winds has created a slab that will need time to settle.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 1.5 - 2.5

Persistent Slabs

60-80cm of snow overlays a layer of surface hoar in sheltered zones, and a sun crust on steep, solar aspects. There has been limited activity on this layer in recent days, but the new load from the incoming storm could re-awaken this problem.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 1 - 3