Human triggered avalanches remain possible at all elevations. A cautious approach to backcountry travel is recommended.
Weather Forecast
TUESDAY NIGHT -Mainly cloudy with scattered flurries / southwest winds 10-20 km/h / alpine low temperature near -13WEDNESDAY - A mix of sun and cloud / north winds 10-20 km/h / alpine high temperature near -11THURSDAY - A mix of sun and cloud / west winds 10-20 km/h / alpine high temperature near -13FRIDAY - Mainly cloudy with flurries, 2-4 cm / southwest winds, 15-35 km/h / alpine high temperature near -11
Avalanche Summary
On Monday a few size 1-1.5 wind slab avalanches were reported, and some loose dry avalanches to size 1.5 were also reported. One notable report from Monday was of a size 2 natural persistent slab avalanche on a northeast aspect at 2000 m. This avalanche occurred on the persistent weak layer that was buried in January. Natural avalanche activity on this layer has mostly tapered off, so this came as a surprise to the observer.On Sunday, several natural and human triggered wind slab avalanches up to size 2 were reported. Several natural loose snow avalanches were reported on steep solar terrain, size 1.5-2.5.On Saturday, skiers triggered a few small (size 1) storm slabs and wind slabs as well as one larger (size 2) persistent slab avalanche. The persistent slab avalanche was triggered on a north aspect at 2100 m and failed on a 60 cm deep surface hoar layer.
Snowpack Summary
10-15 cm of snow has been blown around by recent strong northerly winds, forming wind slabs in alpine and treeline terrain.Two prominent weak layers have been responsible for several dangerous avalanches in the past two weeks. The upper layer was buried at the end of January and lies approximately 40 cm below the surface. The deeper one was buried mid-January and lies approximately 75 cm below the surface. Both consists of a mix of surface hoar (feathery crystals) and facets (sugary snow) and may lie on top of a sun crust on southerly aspects. Both layers are potentially reactive and in any given location, one or both could exist in the snowpack. These weak layers are most prevalent at treeline and below, but may also be found in sheltered areas in the alpine.Average snow depths are approximately 300 cm. Very sporadically, failures have occurred near the base of the snowpack in this region, or in neighboring regions. These releases have almost all been from high alpine areas, possibly triggered close to rocky features.
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.