Very dangerous avalanche conditions exist in this region at this time.
Confidence
Poor - Timing, track, or intensity of incoming weather is uncertain
Weather Forecast
Saturday: 5-10 cm new snow is expected, with extreme winds gusting from the SW to 110 km/h. Freezing levels around 1800 m. Sunday: Flurries or light snowfall. Winds strong southwesterly. Freezing levels around 1300 m. Monday: Further light precipitation with strong winds and freezing levels around 1300 m.
Avalanche Summary
On Friday, a natural avalanche cycle occurred up to size 3 in response to very warm temperatures and continued loading of exposed start zones by high winds. Over the past few days, there have been several reports from in or near the region of near misses, including a snowmobiler who triggered an avalanche and was buried for around 30 minutes, remote-triggered avalanches, and slab avalanches running into unusually low-angled terrain.
Snowpack Summary
Intense warming on Thursday and Friday was making the surface snow moist in many places. 20 to 50 cm of recent storm snow has been reported from different parts of this region. Winds from the SW and the NW have set up wind slabs in lee areas in exposed terrain. The mid February surface hoar layer is now down between 40 & 100cm and is more prevalent in the west and south of the region, particularly in the Flathead. Recent snowpack tests as well as a rider-triggered avalanche on this weak layer indicate that it still has the potential to be triggered in many areas and if it is triggered, a large avalanche could result. Remote-triggering, triggering from below and triggering on low-angled terrain are also concerns. Lingering concern remains for basal facets, particularly in shallower snowpack areas with steep, rocky start zones. Cornices are becoming well developed in response to recent winds and are likely starting to droop with the warm temperatures.
Problems
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.
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.
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.