Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Regions
Glacier.
The likelihood of triggering a slab is relatively low, but the consequences are high! Even a small avalanche in the wrong terrain feature can have penalties.
Weather Forecast
A mix of sun and cloud today; the alpine will reach -11c, and winds may change direction to the NW. Continued cool temps with light winds and flurries tomorrow, fl will remain at valley bottom. On the weekend it will warm up and start storming; forecasts are showing 20+cm should fall by Monday morning accompanied by strong SW winds.
Snowpack Summary
Over half of our snow pack can be attributed to recent December snowfalls. Pockets of wind slab are lingering in lee features and cross loaded slopes in the alpine and treeline. The Dec 9 and Nov 21 interfaces are down ~100-120cm and still producing Hard and Sudden test results. We have no persistent weak layers in the upper snowpack.
Avalanche Summary
No new significant avalanches have been observed in the HWY corridor, or reported from the back country in several days. There is a interesting MIN report from just east of Glacier National Park from the 23rd of Dec. Snowmobile triggered size 2.5-3 deep slab avalanche on a NW aspect near Silent Pass.
Confidence
Due to the number and quality of field observations
Problems
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.