Archived

Avalanche Forecast

Feb 18th, 2017–Feb 19th, 2017

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

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: South Coast Inland.

Watch for signs wind transport in exposed terrain. Moderate to strong winds and light snowfall on Sunday may form new wind slabs.

Confidence

Moderate - Intensity of incoming weather systems is uncertain on Sunday

Weather Forecast

5-10 cm of new snow is forecast between Saturday evening and Sunday afternoon. Freezing levels are expected to reach around 1200 m and alpine wind is forecast to be moderate to strong from the southwest. 10-20 cm of new snowfall forecast between Sunday evening and Monday afternoon. Freezing levels are forecast to reach around 1400 m in the afternoon and alpine wind is forecast to remain moderate to strong from the southwest. Another 5 cm of snow is currently forecast for Tuesday with afternoon freezing levels 1000 m and light to moderate alpine wind.

Avalanche Summary

No new avalanches were observed on Friday. On Thursday, explosive control in the Duffey triggered several size 2-2.5 slabs with 30-50 cm thick crowns, noted for pulling into low angle terrain above the start zones. Widespread natural activity was reported on Wednesday and early Thursday during the warm storm system. Many of these avalanches were wet and gouged all the way to ground in confined paths.

Snowpack Summary

In the Duffey above around 1800 m elevation, 20 cm of heavy powder overlies the widespread mid-February crust layer. Wind slabs and cornices are being reported in north facing alpine terrain. Below around 1800 m, the surface crust is reported to be supportive to the weight of a skier. Two surface hoar layers down 100 cm and 150 cm are still reactive in snowpack tests but would be very difficult to trigger without something heavy like a cornice fall or smaller avalanche stepping down.

Avalanche Problems

Wind Slabs

Old wind slabs may still be reactive in northerly alpine terrain. New snow and moderate southwest wind will likely form thin new wind slabs on Sunday which may be touchy where they overlie a crust. Large lingering cornices may also still be weak.

Avoid freshly wind loaded features.Use ridges or ribs to avoid pockets of wind loaded snow.Avoid areas where the surface snow feels stiff or slabby.

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2