Fast travel and good weather make for some of the best conditions in weeks. The snowpack has gained a lot of strength but problems continue to linger in the high and shaded terrain where deep layers are not protected by thick crusts.
Weather Forecast
After a cold start to the day on Monday clearing skies and light winds will allow modest heating under a gradual warming trend. By Wednesday freezing levels could reach the alpine especially combined with clear skies however winds may start to increase as well. More cloud is expected by Thursday. Solar heating seems like the variable to watch.
Snowpack Summary
10cm of snow that fell over the weekend sits on rain and temperature crusts to 2000m and thin solar crusts to mountain top. Below this old windslabs cap the 50 to 80 cm slab that seems well bonded to the Jan 31 crust. The Mid-December layer down about 1m average is still a concern in high shaded terrain where there are no strong crusts above it.
Avalanche Summary
There was significant solar and heat induced loose moist activity while conditions remained warm last week. Things have cooled over the weekend and the snowpack has begun to refreeze creating strong surface crusts below tree line. Avalanche activity has diminished as a result with no new avalanches seen since Saturday.
Confidence
Freezing levels are uncertain on Wednesday
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.
Cornices
Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.