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Archived

Avalanche Forecast

Dec 5th, 2019–Dec 6th, 2019
Alpine
3: Considerable
Treeline
2: Moderate
Below Treeline
1: Low
Alpine
3: Considerable
Treeline
3: Considerable
Below Treeline
1: Low
Alpine
3: Considerable
Treeline
2: Moderate
Below Treeline
1: Low

Regions: Sea To Sky.

Human triggered avalanches are likely in alpine terrain due to significant amounts of new snow and wind.

Confidence

High - We are confident the likelihood of avalanche will increase with the arrival of the forecast weather.

Weather Forecast

THURSDAY NIGHT: 10-25 cm of snow above 1600 m (rain below), 50 km/h wind from the southwest, alpine temperatures around -3 C.

FRIDAY: 10-20 cm of snow above 1800 m (rain below), 50 km/h wind from the southwest, alpine high temperatures around -1 C.

SATURDAY: 20-30 cm of snow above 1400 m (rain below), 30 km/h wind from the southwest, alpine high temperatures around -3 C.

SUNDAY: Mix of sun and cloud, light wind from the north, alpine high temperatures around -3 C.

Avalanche Summary

Heavy snowfall on Thursday night could result in a natural cycle of avalanches overnight and leave storm slabs primed for human triggering on Friday. Prior to the storm there were reports of a few small (size 1) slab avalanches triggered by skiers and explosives on Wednesday. They were 20-30 cm thick and ran on a hard crust. This crust could provide a bed surface for large avalanches to run on during the storm.

Snowpack Summary

A return to stormy weather is bringing much needed snow to the Sea to Sky region. 20-40 cm of new snow is possible by midday Friday, with another storm pulse coming Friday night. Not to far beneath this new snow is a hard crust that formed in late November. Recent snowpack tests have shown the snow above this crust is weak and could provide a bed surface for avalanches to run on. Typical snowpack depths in the alpine currently range between 50 and 150 cm, depending on the amount of wind affect. Snowpack depths taper quickly with elevation as most treeline terrain is still below the threshold for avalanches.

Avalanche Problems

Storm Slabs

20-40 cm of new snow and strong wind will make storm slabs very easy to trigger at upper elevations. A buried crust beneath the storm slab could cause wide propagations and large avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely - Very Likely

Expected Size: 1 - 2.5