Regions
Northwest Inland.
Human triggering of large persistent slab avalanches remain possible; especially in rocky, alpine terrain with a shallow or highly variable snowpack depth.
Weather Forecast
FRIDAY NIGHT: Cloudy with isolated flurries; 0-3 mm. / Strong, southeasterly winds / Alpine low -3 C / Freezing level dropping to 1200 m.SATURDAY: Cloudy / Moderate, southwesterly winds / Alpine high -2 C / Freezing level 1200 m.SUNDAY: Sunny / Light, southeasterly winds / Alpine high -1 C / Freezing level 1400 m.MONDAY: Mostly sunny / Light, northeasterly winds / Alpine high -1 C / Freezing level 1500 m.
Avalanche Summary
Natural avalanche activity will taper off with the cloudy skies and cooling temperatures. Concern remains for human triggering persistent slab avalanches on a layer of facets that are down 30-50 cm.
Snowpack Summary
30-50 cm of well settled snow overlies weak facets (sugary snow) that were around March. 10th. which is currently the primary layer of concern for human triggering persistent slab avalanches.Lower down in the snowpack, the base is composed of weak facets. Large avalanches initiating on these facets are most likely in rocky, alpine terrain where there is a shallow or highly variable snowpack depth. They would likely require a large trigger such as a cornice fall, snowmobile, or a group of people standing in the same spot.
Problems
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.