Avalanche activity over the course of the storm has been extensive. Maintain conservative terrain selection while human-triggering remains a concern. Isolated areas will see storm slabs continue to build over Sunday night.
Weather Forecast
Monday: A mix of sun and cloud with isolated flurries and a trace of new snow. Light variable winds. Alpine high temperatures around -10.Tuesday: Mainly cloudy with isolated flurries and a trace to 3 cm of new snow. Light southwest winds. Alpine high temperatures around -9Wednesday: Mainly cloudy with isolated flurries and a trace of new snow, increasing overnight. Light southeast winds. Alpine high temperatures around -6.
Avalanche Summary
Reports from Saturday included numerous observations of storm slabs releasing naturally as well as with remote (from a distance) triggering, skier traffic and explosives control. Sizes ranged from 2-3, with crown fracture depths varying from 30-100 cm. This activity occurred on all aspects but was focused at alpine elevations.Friday's storm caused a natural avalanche cycle with numerous size 1-2 avalanches in the top 20-30 cm of new snow. Storm slabs were also reactive to skiers, producing several size 1 avalanches on small terrain features on various aspects.Storm slab avalanches have been reported on a regular basis since Tuesday's storm. Natural avalanches up to size 3 were reported from Tuesday's storm on all aspects from 1900-2800 m. South and west aspects were the most reactive with slabs running on the recently buried late-March crust. In the days following the storm, several size 2 skier and remotely (from a distance) triggered storm slab avalanches were reported. Activity on Thursday was mostly on east aspects at treeline. Skier triggered slabs were mostly 30-50 cm thick and ran on the late-March layer.
Snowpack Summary
Another 20-30 cm of new snow on Friday brought the weekly total throughout the region to 40-80 cm. Strong west winds have redistributed the snow in alpine and treeline terrain.The storm snow sits on a layer buried in late-March that consist of crusts below 1900 m and on south aspects, and surface hoar on shaded aspects at higher elevations.A deeper layer buried mid-March is now 60 to 90 cm below the surface, and is similar to the late-March interface.Deeper persistent weak layers from January and December are still being reported by professional observers, but are generally considered dormant.
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.