Archived

Avalanche Forecast

Jan 16th, 2018–Jan 17th, 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

2: Moderate

The avalanche danger rating below treeline will be moderate

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

2: Moderate

The avalanche danger rating below treeline will be moderate

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: Northwest Inland.

Triggering an avalanche is most likely on steep features in wind-affected terrain.

Confidence

Moderate - Forecast snowfall amounts are uncertain

Weather Forecast

WEDNESDAY: Flurries developing throughout the day with 10-20 cm of snow by the afternoon, strong south winds, alpine temperatures around -5 C.THURSDAY: Another 5 cm of snow, moderate south winds, alpine temperatures around -3 C.FRIDAY: Mix of sun and cloud, light wind, alpine temperatures around -5 C.

Avalanche Summary

Reports from Monday include two small skier triggered avalanches (both size 1). One was a wind slab on a northwest-facing slope under a wind lip and the other was a remotely triggered avalanche on a 50 cm deep surface hoar layer at 1000 m. These small avalanches may be indicators that the upper snowpack has settled into a more reactive slab.

Snowpack Summary

New snow is falling on a temperature crust left over from warm temperatures on the weekend. This crust likely exists well into the alpine. The warm temperatures also settled the upper snowpack, potentially forming a slab above buried weak layers in the top 50 cm of the snowpack. The potential weak layers include a few crusts and surface hoar layers that formed in early January and December. Recent reports suggest the snow is well bonded to most of these layers, but the recent settlement of the upper snowpack may have changed that.

Avalanche Problems

Wind Slabs

New snow will form fresh slabs throughout the day as well as bury old wind slabs. Be cautious around steep rolls in exposed terrain.

Minimize exposure during periods of heavy loading from new snow and wind.Use ridges or ribs to avoid pockets of wind loaded snow.

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2

Persistent Slabs

There's some signs to suggest a reactive slab has finally developed above weak layers in the top 50 cm of the snowpack. Thin areas and convexities are most suspect.

Carefully evaluate and use caution around thin snowpack areas.Choose well supported terrain without convexities.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Unlikely - Possible

Expected Size: 1 - 2.5