Avalanche Forecast

Moderate

A weak frontal system is expected to arrive Friday night bringing moderate to strong southwest winds to the alpine. Freezing levels are forecast to drop to around 1000m by Saturday morning. Cloudy conditions are expected for Saturday morning with light scattered flurries. A mix of sun and cloud is expected for Saturday afternoon with freezing levels around 1500m. Increasing cloud cover is forecast for Sunday with light snowfall in the afternoon. Alpine winds are expected to be moderate from the south with afternoon freezing levels around 1300m. Light snowfall is forecast to continue on Monday with moderate southerly winds in the alpine and afternoon freezing levels around 1300m.Models currently showing 3-6mm of precipitation between Sunday morning and Monday evening.

On Thursday, loose wet avalanches were reported in the south of the region and a natural cycle up to size 2.5 was reported in the north of the region including loose avalanches, slabs, and cornice releases.  On Wednesday, numerous slabs up to size 2.5 were reported on solar aspects in the far north of the region. Some of these releases were over 2m deep releasing on old weak layers. In the south, a natural icefall triggered a size 2.5 slab avalanche. Several loose wet avalanches were also reported. Conditions are expected to improve quickly when the temperatures drop on Saturday but there has been so much heat added to the snowpack over the last few days that some of the deep persistent weak layers may remain reactive for a few days. Once the snow surface develops a widespread supportive crust layer, it will become unlikely to trigger any deep weaknesses. Lingering cornices may remain reactive to human-triggering until there has been substantial cooling.

Over the last couple days, the snow surface has been developing a weak crust overnight which has been quickly breaking down in the morning due to the warm temperatures. With the freezing levels dropping substantially Friday overnight, a more substantial crust is expected to form and is not expected to fully break down on Saturday at higher elevations. If the crust remains supportive, it is expected to cap any deeper weaknesses. The warm temperatures and sun over the last week have woken up deeply buried weak layers within the snowpack. This includes a weak crust/surface hoar layer which was buried down 20-30cm in the north of the region, a widespread crust/facet layer buried in early February down up to 1m, a lingering surface hoar layer from January down around a meter, and weak basal facets at the bottom of the snowpack. These old weak layers may still have isolated potential to produce large avalanches over the weekend, especially with a large trigger such as a cornice fall. Once the snowpack has seen substantial cooling, these layers are expected become inactive.