Avalanche Forecast

Issued: Feb 19th, 2017 3:48PM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Wind Slabs.

rbuhler, Avalanche Canada

South Coast Inland.

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

Summary

Confidence

Moderate - Intensity of incoming weather systems is uncertain on Monday

Weather Forecast

The next low pressure system arrives on the south coast on Sunday evening. 10-15 cm of new snow is expected Sunday overnight with another 5 cm during day on Monday. Alpine wind is forecast to be moderate from the south and southwest. Freezing levels are forecast to be around 800 m overnight and reach around 1100 m in the afternoon. A mix of sun and cloud is currently expected on both Tuesday and Wednesday with the possibility of lingering flurries on Tuesday. Alpine wind is forecast to be light to moderate on Tuesday and light on Wednesday. Afternoon freezing levels are forecast to peak around 800 m on both days.

Avalanche Summary

No new avalanches were reported on Saturday. On Friday, a size 3 persistent slab avalanche was observed up the Hurley at treeline elevation and likely failed on a weak layer from early February. A MIN post describes a natural cornice triggered size 2 storm slab avalanche which occurred on a northeast aspect at 2050 m elevation near the Wendy Thompson hut. Click here for more details. 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. On Monday, thin new wind slabs may develop as a result of light snowfall and moderate southerly winds.Â These slabs may be touchy where they overlie the firm crust layer.

Snowpack Summary

10-20 cm of recent snow overlies the widespread mid-February crust layer. Wind slabs and cornices were being reported in high north facing alpine terrain. Below around 1800 m, the crust is at or near the snow surface and is reported to be solid and supportive to the weight of a skier. Two facet/surface hoar layers in the north of the region 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.

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 Monday which may be touchy where they overlie a crust. Large lingering cornices may also still be weak.

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

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Feb 20th, 2017 2:00PM