Avalanche Forecast

High - We are confident about the likelihood of avalanche activity, what is less certain are their possible size. A small change in the upper snowpack could dramatically change avalanche conditions.

Friday night: 5-10 cm of new snow. Strong southwest wind. Freezing level climbing to 800 m.

Saturday: 5-10 cm of new snow. Strong southwest wind. Treeline temperatures around -5 C. Freezing level 1300 m.

Sunday: 10-20 cm of new snow. Moderate southwest wind. Treeline temperatures around -8 C. Freezing level 500 m.

Monday: 5-10 cm of new snow. Light southeast wind. Treeline temperatures around -7 C. Freezing level 500 m.

Reports from Wednesday and Thursday indicate increasing slab reactivity prior to burial by the current storm. There were several reports of natural size 2 avalanches in alpine terrain as well as several human triggered size 1 wind slabs around treeline. The most reactive slabs were on convex wind-affected slopes. Most avalanches were in the top 20-30 cm of snow.

Avalanche activity is expected to be large and widespread on Saturday.

10-20 cm of new snow falls amid strong wind over 20-40 cm of settling snow from the past week. Beneath this recent snow lies a variety of suspect layers. The most prominent and widespread is a crust that formed during last week's atmospheric river. This crust extends into the alpine (as high as 2400 m), and there is potential for a poor bond to snow sitting above it. There is also a thin breakable crust closer to the surface. We are uncertain about how reactive the recent snow will be as it settles over the upcoming days. The snowpack structure is relatively simple beneath the crust, with treeline snow depths around 100-200 cm.

• Use increased caution at all elevations. Storm snow is forming touchy slabs.
• Fresh snow rests on a problematic persistent slab, don't let good riding lure you into complacency.
• Use conservative route selection. Choose simple, low-angle, well-supported terrain with no overhead hazard.
• Travel in alpine terrain is not recommended.
• The trees are not the safe-haven they normally are at this time. Terrain at treeline is primed for human triggered avalanches.