Avalanche Forecast

Moderate

Increased cloud will develop throughout Sunday with 5-15cm of new snow expected between Sunday night and Monday morning. Generally overcast skies and light flurries are expected on Monday although an intense frontal system will bring moderate to locally heavy snowfall (~ 30cm) to the region on Tuesday. Ridgetop winds will be moderate from the southwest on Sunday night, and then spike to extreme with Tuesday's storm. Freezing levels should sit at about 1400m for the forecast period.

In recent days, loose wet avalanches up to size 2.5 were reported throughout the region. 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, while a full depth slab avalanche was reported on Hudson Bay Mtn. 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 has likely formed 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.