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Avalanche Forecast

Apr 8th, 2023–Apr 9th, 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
3: Considerable
The avalanche danger rating below treeline will be considerable
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
4: High
The avalanche danger rating below treeline will be high
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
3: Considerable
The avalanche danger rating below treeline will be considerable

Regions: Little Yoho.

Strong winds are building slabs in the alpine while warm temperatures and poor overnight recoveries are causing the strength of the snowpack to deteriorate BTL.

As snow and rain are added to the mix Sunday evening, a natural avalanche cycle can be expected to begin.

Confidence

Moderate

Avalanche Summary

Sunshine Village saw a sz 1.5 cornice failure while Lake Louise worked with small wind slabs in the immediate lees and reported a small wind - generated avalanche off of the cliffs on Mt Redoubt.

Snowpack Summary

Up to 5cm of new snow sits over sun crusts on solar aspects. Isolated small wind slabs can be found in the alpine.

A weak, isothermal snowpack is developing BTL with minimal overnight recovery.

Several buried crusts can be found in the top 40cm on solar aspects.

The November depth hoar at the base of the snowpack remains a concern mainly in shallow areas of the Yoho sub-region.

Weather Summary

Freezing levels ~ 1700m overnight Saturday with flurries / showers.

Strong SW winds increase Sunday as freezing levels rise to 2400m.

Winds peak near extreme values overnight Sunday. Freezing level: 2000m with 5 to 10 cm of snow / rain.

Freezing levels higher Monday with 15-30cm of snow / rain. SW winds increase to extreme values.

Terrain and Travel Advice

  • Back off slopes as the surface becomes moist or wet with rising temperatures.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
  • Be aware that wet activity at low elevations is a classic situation for step-down failures in deeply buried persistent weak layers.

Avalanche Problems

Deep Persistent Slabs

The November basal facets at the base of the snowpack have mainly been a concern for triggering in shallow snowpack areas of this sub region however with the weather inputs on track for Sunday the potential for these slabs to be triggered increases.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 2 - 3.5

Wind Slabs

Fresh small slabs have formed over the last two days and will continue to develop through the weekend as SW winds peak near extreme values Sunday evening. As these start to fail naturally, consider them to be potential triggers for larger avalanches.

Aspects: All aspects.

Elevations: Alpine.

Likelihood: Likely

Expected Size: 1 - 2

Loose Wet

With continued poor overnight recoveries, the thin snowpack at the lowest elevations has already gone isothermal losing its strength and structure. With increasing freezing levels and rain in the forecast Sunday, expect this to progress further.

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2