A snowy week is forecast so expect windslabs to build as the snow arrives. Rain/Sun are two things that can quickly deteriorate stability out there right now so keep an eye on these meteorological factors!
Weather Forecast
A snowy week is headed our way it looks like. Over the next few days up to 40cm of snow is expected to fall with strong winds out of the SW in alpine areas. Freezing levels on Thursday are forecast to be around 2300m then dropping throughout the week. When the sun does come out it packs an intense punch and stability on solar aspects can deteriorate quickly. If the forecast freezing levels do come true, we may even see some rain at lower elevations. Watch the sun and freezing levels on your trips!
Avalanche Summary
No new natural avalanche activity was noted on Wednesday.
Snowpack Summary
A clear and cold night brought a good surface freeze to the snowpack overnight, but that changed quickly on steep solar aspects where snow was moist by late morning. Solar aspects have a variety of buried crusts, whereas polar aspects above 2100m have an average of 20cm of dry snow sitting on a variety of previous surfaces. Wind slabs are present everywhere in the Alpine except in sheltered features. Not much natural avalanche activity has occurred with these wind slabs, but many areas like ripe for human-triggering. As previously reported the mid-pack remains dense and strong, but the basal layers are very weak consisting of anywhere between 50 and 100cm of facets sitting on the ground. Forecasters still have low confidence for traveling in large Alpine terrain, unless there has been widespread previous avalanching.
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.
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.
Loose Wet
Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.