Avalanche Forecast

Fair - Timing or intensity of solar radiation is uncertain on Monday

A ridge of high pressure with light winds and many sunny periods are expected on Monday over all of the interior regions. The airmass is still unsettled, and some areas may develop periods of convective flurries. A Pacific frontal system is forecast to move onto the coast during Monday evening, and should develop cloud and precipitation in the Interior around midnight. Expect winds to increase to moderate from the southwest and precipitation to be moderate to heavy by Tuesday morning. This system is expected to continue during the day and into Wednesday morning.

There were less avalanches reported from Saturday; explosive controlled releases up to size 2.0 and a few naturals up to size 2.5. Size 3.0-3.5 natural avalanches continue to be reported regularly from various aspects and elevations on Friday. Another natural size 4.0 avalanche was reported from the region on Thursday that may have released on a weak layer of basal facets, or scoured down to the ground once it was in motion. We are getting into a low probability/high consequence scenario.

Convective flurries continued on Saturday resulting in another 5-10 cm of new snow. The recent series of storms have developed a storm slab that is about 100 cm thick, and reported to be settling and stiffening. The storm slab is sitting on a mix of old hard windslabs and crusts. There is a persistent weak layer (PWL) of buried surface hoar from mid-february that is buried between 100-200 cm that is the main concern. This PWL shears with a fracture character that promotes wide propagations that result in very large avalanches. Recent avalanches up to size 4.5 have exceeded historical avalanche paths and resulted in the demolition of old timber. Very large weak cornices have developed during the recent stormy period. Even brief sunny periods over the next few days may cause natural activity in the storm slab, which may propagate the deeper weak layers.