The winter snowpack still rules the alpine while spring conditions are starting to take effect in the valley bottoms. Watch for surface slabs and massive cornices up high, and be aware of loose, wet avalanches in the valley at the end of your day.
Weather Forecast
Convective cells will be the main story today, bringing isolated flurries and complete white-out in the alpine for brief periods, then followed by a mix of sun and cloud. Freezing levels will rise to 1500m by the afternoon, alpine high of -6*C, and light westerly ridge-top winds. Monday will see a mix of sun and cloud with slightly warmer temp's.
Snowpack Summary
15cm of new snow fell in the last 2 days with strong southerly winds accompanying the 1st wave of snow, then backing down to light winds. Below the new snow lies 30cm of moist snow with several embedded temp crusts. Deeper in the snowpack, old persistent weak layers that include crusts and facets have been reactive to large triggers like cornices
Avalanche Summary
Numerous slab avalanches up to size 3 were triggered by artillery control in the highway corridor yesterday. All slabs were in the upper storm snow, failing on sun or temperature crusts, and were not observed to be digging deeper into the snowpack.
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.
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.