Start early and finish early. Intense solar radiation and very warm temperatures will lead to an increase in hazard levels, possibly reaching HIGH. In addition to the problems discussed below, cornices and their underlying slopes should be avoided.
Confidence
Moderate - Timing or intensity of solar radiation is uncertain
Weather Forecast
Wednesday should be cloudy with sunny periods and isolated wet flurries (possibly rain). Freezing levels will climb to 2600m. Alpine temperatures are expected to reach a high of 2 C. Ridge-top winds will be out of the north at 20 km/h gusting to 50 km/h.
Avalanche Summary
Several loose wet avalanches up to size 2.0 were observed today in steep alpine terrain on solar aspects. Many of these initiated from shallow rocky areas.
Snowpack Summary
The snowpack is settling under the influence of intense solar radiation and daytime heating. Moist snow observed today on all solar aspects up to mountain top and on northerly aspects up to 2200m. Numerous buried crusts are found on all but sheltered north aspects, and many of these crusts are producing shears in snowpack stability tests in the easy to moderate range. We are also observing consistent shears in the hard range deep in the snowpack on the Jan 6th interface down between 100 and 130cm. The basal layers consist of large depth hoar and facets. Slabs up to 50cm thick are still found in lee and cross-loaded features in the Alpine. Much of the region has a snowpack with a dense mid-pack overlying very weak basal layers which indicates the potential for full depth avalanches, triggered either from a large load (such as a cornice) or from a step-down from an avalanche initiated in the upper snowpack. The snowpack is not yet in typical "spring condition", though it is evolving that way.
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.
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.
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.