Though avalanche danger may be decreasing, the potential exists to trigger persistent slab avalanches. While these avalanches are becoming less likely, the consequences are high. The uncertainty associated with complex snowpacks is best managed with conservative terrain choices.
A weak layer of surface hoar that was buried around Christmas is now down about 50-80 cm and is most prevalent at treeline and below treeline.
Two more persistent weak layers buried in early/mid-December are now 90-150 cm below the surface. The form and distribution of these layers are highly variable and may vary significantly from one valley to the next, and between elevation bands.
Recent fresh snow with some moderate wind has created storm slabs that may still be easy to trigger in some areas.
THURSDAY NIGHT - Cloudy with clear periods / light to moderate southeast wind / alpine low temperature near -7
FRIDAY - A mix of sun and cloud / moderate south wind / alpine high temperature near -5
SATURDAY - A mix of sun and cloud / light southeast wind / alpine high temperature near -7
SUNDAY - A mix of sun and cloud / light southeast wind / alpine high temperature near -6
Storm slabs will likely be easiest to trigger in wind loaded areas, as well as in the trees where they may rest on a buried surface hoar layer.
Numerous natural storm slab avalanches size 2-3.5 were reported in the neighboring Glacier National Park region on Wednesday.
A few natural and human triggered storm slab avalanches size 1-2 were reported on Tuesday. Natural storm slab avalanches up to size 3 were also reported in the nearby Glacier National Park region on Tuesday.
It is notable that there were several human triggered avalanches reported at lower elevations in the neighboring Glacier National Park region on Monday. These avalanches highlight the potential to trigger avalanches in the trees. Reports of these can be viewed here, here, and here.
Around 50-80 cm of recent fresh snow now sits on a weak layer of surface hoar that was buried around Christmas. This layer is most prevalent at treeline and below treeline. Previous moderate to strong winds have likely redistributed the new snow, creating storm and wind slabs.
Two persistent weak layers buried in early/mid-December are now down about 90-150 cm. The form and distribution of these layers are highly variable and conditions may differ significantly from one valley to the next. The first layer has been primarily reported as small surface hoar. The next layer has been reported as a thin freezing rain crust, surface hoar, or thick rain crust depending on elevation and location. This layer also remains a concern.
