Storm slabs may be reactive to human triggering, especially in wind loaded areas, and at upper elevations. Watch for signs of instability such as whumphing, cracking and recent avalanches.
Weather Forecast
FRIDAY NIGHT - Mainly cloudy with clear periods / northwest winds, 10 km/h / alpine low temperature near -12SATURDAY - A mix of sun and cloud / northwest winds 10 km/h / alpine high temperature near -9 SUNDAY - Mainly sunny / southwest winds 10-15 km/h / alpine high temperature near -9MONDAY - Flurries, 5-10 cm / south winds 20-40 km/h / alpine high temperature near -6
Avalanche Summary
On Friday, there were preliminary reports of human triggered storm slab avalanches up to size 2. There were also reports of a natural avalanche cycle to size 2.5 in the neighboring Glacier National Park region.On Thursday, there were reports of a few human triggered size 1 storm slab and loose snow avalanches. There were also a few reports of explosives triggered avalanches size 2-2.5.On Tuesday there was one size 1 persistent slab avalanche reported on a north aspect at 1100 m. It failed on the late January persistent weak layer, 40 cm deep and was triggered remotely (from a distance).
Snowpack Summary
10-30 cm of recent storm snow is sitting mainly on wind slabs and facets (sugary snow), as well as surface hoar (feathery crystals) in sheltered areas and a crust on sun exposed slopes. There are a two weak layers in the upper snowpack that were buried in mid and late January. These can be found approximately 40-80 cm deep. Both layers consist of surface hoar and may be associated with a crust on steep, south facing slopes. These weak layers have been most reactive at lower elevations. Avalanche occurrences on these layers have tapered significantly, however it may still be possible to trigger an avalanche on these layers in isolated areas such as steep cutblocks and large open glades.The lower snowpack is generally considered to be strong, except for shallow, rocky areas where the cold temperatures continue to facet (weaken) the snowpack.
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.