Lizard-Flathead

A Special Public Avalanche Warning is in effect for this region. Recent storm snow sits above a suspect weak layer, making for tricky travel conditions.

Moderate -

SATURDAY NIGHT: Cloudy with clear periods, moderate wind from the south, alpine temperatures drop to -7 C.SUNDAY: Increasing cloud throughout the day with isolated flurries and trace accumulations possible in the afternoon, moderate wind from the southwest with strong gusts, freezing level up to 1200 m, alpine high temperatures around -2 C.MONDAY: Mostly cloudy with isolated flurries, strong wind from the southwest, freezing level up to 1500 m, alpine high temperatures around -1 C.TUESDAY: 15-30 cm of snow, strong wind from the southwest, alpine temperatures possible reaching 0 C.

On Saturday a skier remotely triggered a large avalanche on a northeast facing slope at treeline in the Corbin area. Some recent large natural avalanches were also reported at treeline elevations in the Harvey area that failed on deeper crust layers. Smaller wind slabs (size 1) were occurring naturally and reactive to skiers throughout the region on Saturday. Evidence of a natural avalanche cycle was observed on Friday, including size 2 avalanches failing on storm snow in alpine terrain. Explosives triggered several large avalanches (size 2-3) in the storm snow on north to east aspects between 1800 and 2100 m. Some of these avalanches propagated long distances across terrain, suggesting the snow has a poor bond to the old snow interface.

Roughly 30-50 cm of recent storm snow sits above a weak layer composed of large surface hoar, facets, and/or sun crust. There have been numerous signs of the new snow bonding poorly to this layer including remote triggering from low angle terrain, shooting cracks, and wide propagations in avalanches. Ongoing wind loading is forming thicker slabs at higher elevations.Several other weak layers have been observed in the lower snowpack such as early season crusts with weak facets. The most concerning crust is most prevalent at and above treeline and is likely most problematic on north-facing features, especially those that are large and planar in nature.