Riding conditions are excellent right now but isolated problems still exist. Soft wind slabs may still be lingering around ridge crests in the alpine. Sluffing can be expected on steep sun-exposed slopes during the heat of the afternoon.
Confidence
Moderate - Timing or intensity of solar radiation is uncertain
Weather Forecast
High pressure is the dominant feature for the foreseeable future. In the alpine, sunny conditions are expected for the next few days but most of the valleys will likely to be under valley fog. On Thursday, treeline temperatures will be around -5C with colder temperatures in the valleys. Alpine winds may be moderate from NE in the morning but should ease during the day. On Friday, a layer of above freezing air is expected to invade the alpine. By Saturday, temperatures could be a few degrees above zero from around 2000m to 3000m elevation. On both Friday and Saturday, alpine winds should be light and above the valley fog the conditions should be clear and sunny.
Avalanche Summary
Over the last few days, several small loose dry avalanches and one size 1.5 wind slab have been observed. Persistent slabs were last triggered about a week ago. Unfortunately these types of problems don't heal quickly, so they remain on our radar. This problem may wake up with the upcoming warm temperatures in the alpine. Progressive warming in the alpine with ongoing sunny conditions should result in ongoing loose natural avalanches from south-facing slopes and by the weekend may create slab properties within the recent storm snow.
Snowpack Summary
20-30 cm of low-density snow typically overlies a well-settled mid and lower snowpack. Surface hoar and near-surface facets may be mingled within the upper few cm. Storm slab properties may change and become more cohesive as the alpine gets some sun and warmer temperatures. Wind slabs, found in the lee of ridges and ribs, are still reactive in some spots and healing in others. A weak layer which was buried in early December is down about 40-100 cm. At and below treeline, it mainly consists of large surface hoar. At higher elevations, it consists of a sun crust, facets, and/or small surface hoar. This layer is still reactive in some snowpack tests and has produced at least one human-triggered avalanche in the last week. The persistent slab is a low probability, high consequence problem. Below this layer, the snowpack is thought to be generally strong and well-settled.
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.
Loose Dry
Loose Dry avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.