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Archived

Avalanche Forecast

Dec 20th, 2019–Dec 23rd, 2019
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
4: High
The avalanche danger rating at treeline will be high
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
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

Regions: Waterton Lakes.

The storm rages on! Wet snow and rain will continue to load the snowpack on Friday night into Saturday. This continues to be a good time to avoid avalanche terrain.

Weather Forecast

Heavy wet snow or rain will continue Friday night and possibly Saturday with 110km/h winds and freezing levels near 2000m. There is some disagreement in the weather models on how much precipitation will arrive on Friday night and Saturday with amounts between 10 and 30cm, but the main event should be over by Sunday.

Snowpack Summary

30cm of wet snow and rain has arrived with extreme northwest winds and a freezing level around 1900m, providing a shock to the snowpack. A weak crust facet combo formed in November is down 60cm, and additional crust/facet layers formed in October form the bottom of the snowpack.

Avalanche Summary

No recent natural activity has been observed but visibility is poor. You can be sure slabs are building where the precipitation has come as snow.

Confidence

Intensity of incoming weather systems is uncertain

Avalanche Problems

Storm Slabs

The atmospheric river continues to bring heavy snowfall accompanied by 120km/h southwest winds and rain below 1700m. Snowfall amounts are uncertain on Saturday, but winds will be strong and freezing levels will remain high.

  • If triggered the storm slabs may step down to deeper layers resulting in large avalanches.
  • Avoid avalanche terrain during periods of heavy loading from new snow, wind, or rain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Very Likely

Expected Size: 1 - 2

Persistent Slabs

Melt freeze crusts and facets from early season snowfalls are lurking at the bottom of the snowpack. This layer may come alive again with loading form the incoming storm.

  • Good day to make conservative terrain choices.
  • Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 2 - 3