Archived

Avalanche Forecast

Jan 12th, 2017–Jan 13th, 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

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 Rockies.

Changing winds have built fresh wind slabs on a variety of aspects and may be reactive to rider triggering.

Confidence

Moderate - Wind effect is extremely variable

Weather Forecast

The dominating arctic ridge is slowly breaking down as we transition to a more zonal (westerly) flow. Cloudy with some sunny periods, light-moderate westerly winds and warmer alpine temperatures will persist through the weekend. A more significant change to come early next week.Friday/ Saturday/ Sunday: Mix of sun and cloud with mostly cloudy skies on Saturday. Ridetop winds will be light from the SW-W and alpine temperatures near -9.

Avalanche Summary

On Wednesday, numerous natural and skier triggered loose dry avalanches up to size 2 were reported from the region. Variability in the winds has been the name of the game and wind slabs may be found on all aspects at upper elevations. Persistent slab avalanches also remain an ongoing concern, creating a low probably, high consequence problem for the region. Extra caution is recommended in shallow snowpack areas.

Snowpack Summary

Up to 20 cm of recent snow has buried a variety of old snow surfaces which consist of heavily wind scoured snow and wind slabs, surface hoar in sheltered areas, and/or widespread faceted old snow. Recent moderate winds from a variety of directions is expected to have redistributed some of this new snow on leeward slopes. The mid pack appears to be quite variable throughout the region and the structure is dependant on snow depth. In deeper snowpack areas, the snowpack appears to be well settled and right side up with isolated concerns for the mid-December weak layer. In shallow snowpack areas and lower elevations, the snowpack is heavily faceted and there are concerns for the mid-December weak facet layer as well as weak basal facets. Due to inconsistencies in snowpack structure region wide, its a good idea to dig down and test weak layers in your local riding area.

Avalanche Problems

Wind Slabs

Recently formed wind slabs may still be reactive to human triggering. Changing wind directions may build wind slabs on all aspects.

Watch for signs of instability such as whumpfing, or cracking. Use ridges or ribs to avoid pockets of wind loaded snow.Avoid areas where the surface snow feels stiff or slabby.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2

Persistent Slabs

Where stiffer snow overlies weak, sugary snow, there is the potential to trigger large, destructive avalanches.

Be aware of the potential for full depth avalanches due to deeply buried weak layers.Danger exists where denser snow overlies weak, sugary snow below.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 2 - 3