The forecast calls for cooler temps but it is now mid February and we have a complex snowpack with persistent weak layers, recently buried melt-freeze and solar crusts with big cornices looming. When the sun pops out, the solar heating is significant
Weather Forecast
Sunday should bring cooler temperatures - freeze levels at valley bottom. Cloudy in the morning and the sun might pop out in the afternoon. Winds will be out of the west 45km/h at treeline. No precipitation anticipated.
Avalanche Summary
To the eastern edge of our forecast region, a fresh 1.5 and a size 2.0 were observed on solar aspects of Mt. Nestor in the alpine. These slabs are likely failing as a result of a combination of wind loaded slabs on top of sun crusts with a bit of local solar warming.
Snowpack Summary
The snowpack is beginning to take on characteristics of late winter/early spring. The january 6th facets are buried about 80cm deep but are giving no results to spotty sudden collapses in isolated locations above treeline and alpine. There are also several melt-freeze & sun crusts from February 11th (40-50 cm) and February19th buried about 10-15cm. A complex array of storm slabs, wind slabs, cornices and deeply buried persistent weak layers in the mid to upper snowpack coupled with variable and difficult to predict results in snowpack tests. Snowpack areas that are thin (less than 100cm) are weak and facetted.
Problems
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.
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.