Regions
Northwest Inland.
This forecast is based on limited information. There is much uncertainty, particularly how weak layers may respond to human triggers. Treat this as a first estimation of avalanche danger and adjust your terrain choices based on observed conditions.
Confidence
Low - Due to the number of field observations
Weather Forecast
Tuesday: Around 5 cm new snow expected with freezing levels around 900 m. Winds strong southerly in the morning, becoming westerly later on.Wednesday: Flurries or light snow. Freezing levels around 900 m. Winds strong southwesterly.Thursday: Flurries or light snow. Freezing levelst around 500 m. Winds strong westerly.
Avalanche Summary
Small slab avalanches and loose dry avalanches were reported from the west of the region over the weekend. Previously, (last Wednesday), several estimated Size 2.5-3 avalanches wereobserved on the Kathlyn face of Hudson Bay Mountain. Please post your observations to the Mountain Information Network. (MIN)
Snowpack Summary
Snowpack depths over the south of the region are above average for late November, with total depths of approximately 150 cm present at treeline elevations and above. The past week of stormy weather delivered about 60 cm of new snow to form the upper snowpack in the region. A thin rain crust may exist at mid-depth within this new snow. Below the new snow, about 20-30 cm of settled storm snow lies above the widespread late October crust. This October crust is present near the base of the snowpack at all elevations and features a layer of weak, sugary grains above it. This "crust/facet combo" layer remains an ongoing concern for step-down potential from large triggers such as a storm slab release. This layer is less of a concern below treeline where it is broken up by vegetation near the ground.
Problems
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.