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Avalanche Forecast

Mar 9th, 2021–Mar 10th, 2021
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
1: Low
The avalanche danger rating at treeline will be low
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
1: Low
The avalanche danger rating at treeline will be low
Below Treeline
1: Low
The avalanche danger rating below treeline will be low

Regions: Sea To Sky.

Recent storm snow has been redistributed into pockets of wind slab at tree line and in the alpine and may continue to be reactive. Watch for denser, deeper drifts near ridge-crests and rollovers.

Confidence

Moderate - Uncertainty is due to how quickly the snowpack will recover and gain strength.

Weather Forecast

TUESDAY NIGHT - Cloudy with clear periods and isolated flurries / light to moderate west wind / alpine low temperature near -5 

WEDNESDAY - A mix of sun and cloud with isolated flurries / light to moderate northeast wind / alpine high temperature near -6 / freezing level 1200 m

THURSDAY - Mainly sunny / light west wind / alpine high temperature near -6 / freezing level 1300 m

FRIDAY - Mainly cloudy with isolated flurries / moderate southwest wind / alpine high temperature near -2 / freezing level 1400 m

Avalanche Summary

On Monday, there were a few explosive triggered size 2 cornices, and a few natural and human-triggered size 2 wind slab avalanches reported. 

On Sunday, small pockets of wind slab were reported releasing naturally and with ski cuts, primarily on northerly aspects near and above 1900 m. Small loose dry sluffs were also observed in steep terrain. 

Explosive control on Saturday produced numerous large cornice and storm slab avalanches, with 50-100 cm crown depths. Explosives also released a very large (size 3) wind slab avalanche on a northeast aspect above 2000 m. 

Reports indicate that a natural avalanche cycle occurred during the storm on Friday, with small to large (size 1-2.5) avalanches releasing in the storm snow across all aspects and elevations. 

Snowpack Summary

50-100 cm of snow fell over the weekend and has been settling rapidly. The recent snowfall was accompanied by strong south winds, forming wind slabs on leeward slopes that remain possible to trigger. Massive cornices exist on ridgelines, which can act as triggers on slopes below.

The mid and lower snowpack is well settled and strong in most areas. A weak layer of facets buried in mid-February may still be found but has been gaining strength.

Terrain and Travel

  • Be careful as you transition into wind affected terrain.
  • Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.
  • Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
  • Minimize your exposure time below cornices.

Avalanche Problems

Wind Slabs

Recent strong south winds have had ample snow to drift into reactive wind slabs on lee features at upper elevations. Pay attention to the pattern of wind-drifting in the terrain where you are traveling and watch for cracking or changes in snow stiffness. Triggering large wind slabs on specific features remains possible. 

Aspects: North, North East, East, South East, West, North West.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1.5 - 2.5