Avalanche Forecast

Moderate - Uncertainty is due to the limited number of field observations.

SUNDAY NIGHT: Clearing with some clouds, light wind from the northeast, alpine temperatures drop to -12 C.

MONDAY: Mostly sunny, moderate wind from the west, alpine high temperatures around -8 C.

TUESDAY: Light flurries in the afternoon with trace amounts of snow, moderate to strong wind from the southwest, alpine high temperatures around -8 C.

WEDNESDAY: 5-10 cm of snow overnight then clearing in the afternoon, light to moderate wind from the southwest, alpine high temperatures around -5 C.

A widespread cycle of very large deep persistent slab avalanches occurred a week ago (up to size 3), and while the likelihood of triggering deep persistent slab avalanches has declined, the consequences are severe. The most recent report of a deep persistent slab avalanche was on Friday near Summer Lake (see this MIN report). This avalanche was triggered by a snowmobile in adjacent terrain and shows the possibility of triggering large avalanches from thin spots in rocky alpine terrain.

Small (size 1) wind slab avalanches have been reactive to human triggering the past few days, including a size 2 avalanche that had impressive propagation on Friday. 

The snowpack is gradually recovering from a major storm that delivered 50-100 cm of snow last weekend. Wind has blown around surface snow into unstable wind slabs in steep terrain at higher elevations. The bottom 30-50 cm of the snowpack consists of weak facets and crusts, which resulted in large deep persistent slab avalanches last weekend. These layers are gradually adjusting to the weight of the new snow, and so the likelihood of triggering deep persistent slab avalanches is declining.

• Avalanche hazard may have improved, but be mindful that deep instabilities are still present.
• Avoid convexities, steep unsupported terrain and rocky outcroppings.
• Be careful with wind slabs, especially in steep, unsupported and/or convex terrain features.
• If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.