Although the storm is over, large natural avalanches are still running as of this morning. Expect natural avalanche activity to continue as the sun makes its debut.
Weather Forecast
The storm is over. Expect mostly sun today with cloudy periods. Alpine temperatures around -13.0, light ridge winds and freezing levels remaining at valley bottom. High pressure with nil precipitation continues through the weekend. Weather models show a pulse of moderate precipitation arriving Tuesday night, bringing up to 20cm of snow.
Snowpack Summary
Approximately 60cm of new snow in the past 36hrs is settling into a widespread storm slab. Storm slabs will be deeper and more reactive in wind affected areas. Dec and Jan persistent weak layers are now buried 150-200cm in the snowpack. Height of snow is 350cm at 1900m.
Avalanche Summary
Numerous natural and artillery controlled avalanches up to size 4.0 during the avalanche cycle that accompanied yesterday's storm. Several ran full extent, taking out mature trees. A large natural avalanche, size 3.5, was observed running to the valley bottom this morning in the HWY corridor. Natural activity has not yet subsided.
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.