Archived

Avalanche Forecast

Dec 31st, 2017–Jan 1st, 2018

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

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

Regions: Sea To Sky.

Human triggered avalanches may become more likely as warm temperatures allow the storm snow to settle into a more cohesive slab. Keep a close eye on steep sun exposed slopes throughout the day, warming may initiate natural loose avalanches.

Confidence

Moderate -

Weather Forecast

A warm dry pattern is expected for the next few days. The upper ridge will shift eastward on New Year's Day, which should allow freezing levels on the Coast to rise to around 2500 m. This pattern is expected to stick with us for the foreseeable future. MONDAY: Temperature Inversion with below freezing air in the valley, above freezing (warmer) air between 1400 m and 2600 m, a few clouds, very light northwest wind, no snow expected.TUESDAY: Scattered cloud, freezing level rising to around 2600 m mid-morning, light southwest wind, no snow expected.WEDNESAY: Cloud cover increasing to overcast throughout the day, freezing level around 2700 m, light variable wind, no snow expected.

Avalanche Summary

On Saturday control work produced storm slabs, wind slabs and loose dry avalanches to size 2 with crowns 20 to 50 cm in depth. One isolated loose wet avalanche was reported on a solar aspect which could be a portent of things to come.

Snowpack Summary

Two successive storms produced 50 to 70 cm of storm snow with wind out the southwest, south and southeast that was strong at times. All of this new snow rests on a variety of old surfaces including crust on solar aspects, old wind slabs, facets and isolated surface hoar below treeline. Warming temperatures will likely allow the storm snow to settle into a more cohesive slab. 40 to 100 cm below the surface there is a widespread melt-freeze crust that was buried on December 15th. This layer has not produced much in the way of avalanche activity, but could come to life as the overlying slab becomes more cohesive as temperatures warm. Beneath the December 15th layer, the lower snowpack is generally strong and well settled.

Avalanche Problems

Storm Slabs

The last storm system produced 50 to 70 cm of new snow with winds mainly out of the south. Human triggered avalanches may become more likely Monday as warm temperatures allow the snow to settle into a more cohesive slab.

Avoid wind loaded terrain, especially near ridge crests and roll-overs.As the storm slab problem gets trickier, the easy solution is to choose more conservative terrain.Be alert to conditions that change with elevation and sun exposure.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 2

Loose Wet

Loose moist avalanches may run naturally on steep sun exposed slopes as previously cold snow is introduced to warm temperatures for the first time on Monday.

Avoid sun exposed slopes especially if the snow is moist or wet.Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.Minimize exposure to solar aspects overhead, loose avalanches could travel surprisingly far.

Aspects: North, North East, East.

Elevations: Alpine.

Likelihood: Possible - Likely

Expected Size: 1 - 2