Avalanche Forecast

Moderate - Intensity of incoming weather systems is uncertain on Saturday

SATURDAY Mainly cloudy with snow flurries bringing another 10-20cm, primarily to the western 'upslope' side of the mountain ranges. Freezing levels hovering around 1800m and moderate to strong gusry southwesterly ridgetop winds. SUNDAY: Continued unsettled conditions with power flurry activity bringing another 10-20 drainage dependant, gusty winds and freezing levels generally not much higher than 1500m. MONDAY: A mix of sun and cloud, isolated light flurries possible with freezing levels remaining near valley bottoms and moderate to strong southwesterly ridgetop winds.

Reports from Thursday include numerous natural avalanches up to Size 3 in response to heavy loading from snow, wind and rain. Most of the natural avalanches were storm and wind slabs, but a few persistent slabs also ran naturally on the late February persistent weal layer. Explosives and other artificial triggers (i.e. snow cats) produced additional Size 2-3 persistent slab activity, with remote and sympathetic triggers as well as 50-100cm thick slab releasing from the impact of the dropped charge, before it exploded.

15-25cm of fresh snow has loaded to 40-50cm wind slabs on the leeward side of ridgecrests and terrain features. These fresh storm and wind slabs are bonding poorly to a thin crust at lower elevations depending on the drainage and/or overloading lower density previous storm snow creating an unstable "upside down" upper snowpack that is sliding easily on a widespread rain crust, which extends into alpine elevations. A persistent weak layer buried late-February is typically down 60-100cm and highly sensitive to human triggers as indicated by recent avalanche activity. This weakness is widespread buried surface hoar on sheltered slopes above 1700m, and a crust potentially with associated facets on previously sun-exposed slopes (primarily south aspects).