Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.
Regions
Northwest Inland.
Confidence
Fair - Track of incoming weather is uncertain
Weather Forecast
Thursday: Strong ridgetop winds from the SW with snow amounts near 10cms. Treeline temperatures near -5. Friday-Saturday: Freezing levels may rise to 1100m. Mix of snow and rain at lower elevations. Snow amounts near 12cms. Ridgetop winds strong from the west.
Avalanche Summary
No new avalanche activity has been reported. Any information (professional or recreational) from the field is highly appreciated. Please send your observations to [email protected].
Snowpack Summary
Early in the week the region received up to 20cms of new snow accompanied by strong southwest winds. Storm snow and wind slabs are forming. There could be up to 50cms total from last week's snowfall and the current snowfall loading the weak layers in the upper part of the snowpack. These weak layers are the December 12th surface hoar/crust/facet combo. What is the tipping point of this weak interface? In areas where this interface has reached its threshold avalanches have occurred. If they have yet to happen naturally, I suspect they are very touchy and will react to a rider trigger. Observations suggest there is faceting above and below the crust. The crust being a result from rising freezing levels, then the early December dry spell. This crust is widespread and is lingering in most start zones up to 2000m. In short, the upper snowpack is variable and showing easy shears in test results. The midpack seems to be well settled and strong.
Problems
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.
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.