Lingering storm slabs remain a concern, especially in the alpine. Avoid steep unsupported slopes and convexities. Use extra caution on sun-exposed slopes during the heat of the afternoon.
Weather Forecast
Thursday should be a mix of sun and cloud. Freezing levels are forecast to peak around 2000m and alpine winds are expected to increase to strong from the SW to W. Friday should be similar with a mix of cloud and sun, and moderate to strong alpine winds from the SW. Freezing levels are expected to climb as high 2500m on Friday afternoon. Light precipitation is possible on Saturday and freezing levels are forecast to drop back to around 2000m.
Avalanche Summary
A widespread natural avalanche cycle to size 2.5 occurred on Monday during the storm. These were primarily storm slab avalanches but several stepped down to deeper persistent weak layers or to the ground in steep unskiable terrain. At lower elevations, loose wet avalanches up to size 2.5 were reported as well as isolated wet slabs. Natural activity quickly tapered off following the storm but the storm slab is expected to still be reactive to human-triggering. It is best to avoid steep unsupported slopes and convexities, as well as steep gully features. There is also concern for avalanches to step down to deeper persistent weak layers in isolated areas. Loose wet avalanches are a concern on sun-exposed slopes during the heat of the afternoon.
Snowpack Summary
The recent storm snow is settling into a cohesive slab which is typically 30-40cm thick. Up to at least 2000m elevation, the snowpack below the new storm snow is moist or wet from the warming and heavy rain last week. A weak rain crust sits between the storm snow and the lower snowpack. The thick mid-February crust has broken down and is no longer supportive. There are a couple older persistent weak layers in the midpack that are probably breaking down but will remain an isolated concern while the snowpack remains warm.
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.