Storm snow totals of up to 50cm have formed slabs in the alpine and upper treeline terrain. The warm sun of mid-March will be a major factor in increasing the hazard on solar aspects during any sunny period. Plan your approach to terrain accordingly.
Weather Forecast
A mix of sun and cloud expected on Tuesday with freezing levels near 2100m. Alpine temperatures should reach -1 celsius and winds will be light from the South. Wednesday should be a bit cloudier with a trace of precipitation.
Avalanche Summary
Several naturally triggered loose avalanches (both dry and wet) occurred on all aspects in steep terrain at alpine and treeline elevations up to size 1.5. In addition, ski cutting produces sluffs up to size 1.5 on steep north facing terrain. A few slab avalanches also occurred in the past 24hrs. These are all naturally triggered slabs (some by solar triggering) and occurred in alpine terrain on all aspects up to size 2.0.
Snowpack Summary
The snowpack is highly variable depending on aspect and elevation. Up to 50cm of storm snow has fallen at treeline. On polar aspects moderate shears exist at the storm snow interface (down 50cm) and easy to moderate shears exist within the storm snow down 15 to 30cm. Thin storm slabs formed early in the storm, but then the winds backed off. This has left hidden slabs buried under low density snow at treeline. In the alpine slabs are prominent and a few avalanches have occurred related to this problem (see Avalanche Activity Discussion). On solar aspects a completely different situation exists. On these aspects the storm snow has already settled to 30cm and seems well bonded to the underlying crusts below 2400m. Above this elevation the storm snow seems to have bonded less well and numerous point release avalanches have been observed in steep alpine terrain. The surface snow on solar aspects was moist by midday. On all aspects below 2100m the storm snow sits on a very dense and strong rain crust (about 1cm thick) that was formed on Saturday. This rain crust is supportive to skier traffic.
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.
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.