Archived

Avalanche Forecast

Dec 15th, 2019–Dec 16th, 2019

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

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 Columbia.

At and below treeline, 20 to 30 cm of storm snow rests on surface hoar which teeters on the brink of becoming a touchy storm slab problem.

Confidence

Moderate -

Weather Forecast

SUNDAY NIGHT: Cloudy with clear periods, light to moderate northwest wind, alpine high temperature -10 C.

MONDAY: Flurries, accumulation 5 cm, moderate west wind, alpine high temperature -9 C.

TUESDAY: Flurries, accumulation 5-10 cm, moderate west wind, alpine high temperature -6 C.

WEDNESDAY: Scattered flurries, moderate southwest wind, alpine high temperature -6 C.

Avalanche Summary

On Saturday there were two reports of skier triggered persistent slab avalanches size 1-1.5. One was on a south aspect at 2200m and was about 25-45 deep.

Reports from Thursday and Friday mostly describe sloughing and small loose dry avalanches up to size 1. Soft storm slabs propagating at ridgetops but breaking up quickly as they ran, were also limited to size 1.

Snowpack Summary

20-30 cm of new snow has covered a widespread layer of large, feathery surface hoar crystals. The new snow can be expected to gain cohesion and settle into a slab treeline and below.

A weak layer formed in late November is now buried around 1 m below the surface. This is the layer of concern relating to the listed persistent slab avalanche problem. The weak layer may present as surface hoar, a crust, facets or a combination, depending on elevation and aspect. Below this, a variety of crusts from late October are buried deeper in the snowpack.

Avalanche Problems

Storm Slabs

20 to 30 cm of recent storm snow rests on a widespread layer of large surface hoar. The storm snow is teetering on the edge of becoming a touchy slab problem,

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 1 - 2

Persistent Slabs

A couple of weak layers formed in late November and early December are now sitting about 1 m below the surface. This layer may present as surface hoar, a crust, facets or a combination of those, depending on elevation and aspect.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Unlikely - Possible

Expected Size: 2 - 3