Archived

Avalanche Forecast

Dec 19th, 2016–Dec 20th, 2016

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

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

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 Rockies.

New and potentially reactive wind slabs have formed. The best and safest riding may be at treeline in areas sheltered from the wind.

Confidence

Low - Due to the number of field observations

Weather Forecast

Tuesday: 8-15cm of new snow / extreme west winds / Freezing level at 1200mWednesday: Mix of sun and cloud with light flurries / Strong southwest winds / Freezing level at 1100mThursday: Mix of sun and clouds / Strong southwest winds / Freezing level at 1000m

Avalanche Summary

New snowfall and strong southerly winds are expected to have promoted new wind slab activity in exposed terrain. Forecast new snow and wind on Tuesday will likely spark another round of wind slab activity in higher elevation, wind-exposed terrain.

Snowpack Summary

New snow on Sunday night and strong southerly winds have likely created fresh wind slabs in exposed terrain. The new snow buries a variable surface that developed over the last week of cold, dry, and windy conditions. This interface consists of scoured surfaces and wind slabs in wind exposed terrain, widespread faceting of the upper snowpack, and surface hoar up to 20 mm in sheltered areas. In sheltered areas, there may be another layer of surface hoar in the upper snowpack which was buried around December 10. The mid pack is generally well settled. The thick crust from mid-November is near the bottom of the snowpack and recent tests suggest that the crust is currently well bonded to the surrounding snow. Below treeline, the snowpack is very shallow and early season hazards such as stumps, rocks, and open creeks are still a major concern.

Avalanche Problems

Wind Slabs

New snow and wind on Tuesday will add to the size and reactivity of existing wind slabs. The new snow buries a weak interface which may prolong the reactivity of these slabs.

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

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely - Very Likely

Expected Size: 1 - 2