New snow falling Monday into Monday night has promoted storm and wind slab development.
Confidence
Moderate - Forecast snowfall amounts are uncertain
Weather Forecast
MONDAY Night: Snow, accumulation 5-15 cm / moderate southwest wind / alpine temperature -8 CTUESDAY: A mix of sun and cloud with isolated flurries / light northwest wind / alpine temperature -6 C / freezing level 1100 m WEDNESDAY: Cloudy with sunny periods / light to moderate west wind / alpine temperature -8 C / freezing level 900 mTHURSDAY: Cloudy with sunny periods / light southwest wind / alpine temperature - 7 C / freezing level 1000 m
Avalanche Summary
Expect the likelihood of triggering storm and wind slabs to increase with new snow from Monday and Monday night. Reports on Saturday and Sunday include several natural and human triggered storm slab, loose dry and wind slab avalanches to size 1.5.On Friday, there were 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.
Snowpack Summary
20-50 cm of storm snow from the last week 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.