Storm snow has added load to a complex upper snowpack creating touchy avalanche conditions.
Stick to lower angle terrain with no overhead hazard.
There is a weak layer of surface hoar/crust/facets in the upper snowpack. This layer is spotty, but most likely areas to trigger it are on north-facing terrain, which were most recently reactive in the Flathead.
Recent storm snow will likely remain reactive as it settles. Cold temperatures may prolong its reactivity, specifically where it has formed over a crust or is affected by the wind.
A cycle of natural, human, and explosive triggered storm slab avalanches up to size 2 occurred on Tuesday and Wednesday in the Lizard Range. In the Flathead and St Mary's, there have been reports of several remotely triggered (from a distance of 100+ m) storm and persistent slab avalanches up to size 3. Some have had very wide propagations and were 50-60 cm deep.
There was an avalanche fatality in the Matheson Creek area on Tuesday. See this MIN report for more details.
Roughly 50 cm of storm snow has developed touchy storm slabs over an upper snowpack that is variable and contains two distinct weak layers:
50 cm deep, there is a supportive crust on south-facing terrain. On north-facing terrain, this crust is breakable or absent.
Between 60 and 100 cm deep, a persistent weak layer of crust/facets with spotty surface hoar is present.
The persistent weak layer is becoming less reactive, but continues to produce sporadic avalanches, particularly on north aspects where a supportive crust is absent and in less-travelled areas like the Flathead. Recent storm snow has increased the load on these layers.
Friday Night
Mostly clear skies. 10 to 20 km/h west ridgetop wind. Treeline temperature -13 °C.
Saturday
Mostly sunny. 10 to 20 km/h south ridgetop wind. Treeline temperature -10 °C.
Sunday
Mostly sunny. 20 to 50 km/h south ridgetop wind. Treeline temperature -7 °C.
Monday
Mostly cloudy. 5 to 10 cm of snow. 40 to 70 km/h southwest ridgetop wind. Treeline temperature -4 °C.
More details can be found in the Mountain Weather Forecast.
