Use caution when riding in new terrain. Now is not the time to "Go Big"A Special Public Avalanche Warning is in effect for this region
Confidence
Moderate - Intensity of incoming weather systems is uncertain
Weather Forecast
A low pressure system coming up from the south west will brush the area Saturday afternoon and Sunday morning and may bring 5 to 10cm of moist snow to the region. Freezing levels will fluctuate between 200 m overnight and 1000 m in the afternoon on Sunday. Monday the freezing level will again rise to 1000 m with cloudy skies and the possibility of flurries
Avalanche Summary
Numerous slab avalanches up to size 2.5 have been reported in the past 2 days. Many were naturals as a result of recent storm loading. A large number were skier controlled. Many of these failed around treeline and below, on buried surface hoar, about 20-40 cm deep. Many of these were triggered remotely, highlighting the volatility of the persistent slab. An increasing number of wind slabs have also been failing at alpine/ treeline elevations, and also running on surface hoar. It is likely that a natural avalanche cycle occurred on Friday in response to the warm, windy storm.
Snowpack Summary
Recent snowfalls have created new storm slabs throughout the region and wind slabs on lee features. This has also added load and stress to the already touchy persistent slab. The 40-90 cm persistent slab overlies a variety of surfaces including large surface hoar, sun crusts, rime crusts and facets. This persistent slab is ripe for human and natural triggers and is especially touchy at and below treeline. The mid and lower snowpack are generally well settled and strong.
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.