Avalanche Forecast

Moderate -

Saturday: Mainly sunny with some valley cloud due to a weak temperature inversion. Light northwest winds, moderate to strong at high elevations. Alpine high temperatures of -11, slightly cooler at lower elevations.Sunday: A mix of sun and cloud with cloud increasing over the day. Light variable winds. Alpine high temperatures of -12. Cooling over the day as the temperature inversion breaks down.Monday: Mainly sunny with some valley cloud due to a new temperature inversion establishing. Light north winds, increasing overnight. Alpine high temperatures of -10, cooler at lower elevations.

We have preliminary information of a snowmobiler triggering a size 2 avalanche on a north aspect at 2200 metres in the Hospital Creek area east of Golden on Friday. The individual was potentially deeply buried by the debris and was extricated by their riding companions. The storm slab had a crown depth of 40-60 cm and width of 50 metres. Although this incident did not occur in a forecast region, it gives an indication of potential conditions in the surrounding area.Reports from Thursday included observations of numerous natural and explosives-triggered storm slab releases, generally from size 1.5-2.5. Several more explosives-triggered persistent slabs ran from size 2-3 with crown fracture depths of up to 150 cm and runout distances of up to 400 metres. The adjacent Columbias forecast regions saw storm slab and persistent slab avalanches reaching size 4 and greater. Several historic slides destroyed mature timber along their edges as well as on opposing slopes.Looking forward, it will be essential to maintain elevated caution as ratings shift into the CONSIDERABLE range. As the likelihood of triggering diminishes, the destructive potential of avalanches will remain dangerously high.

Recent accumulations of 20-30 cm have formed reactive new storm slabs on the surface throughout the region, burying pre-existing storm and wind slabs. Collectively, this storm snow overlies a complex and generally weak snowpack structure with four active weak layers that we are monitoring:1) 90 to 140 cm of snow now overlies a crust and/or surface hoar layer from mid-January. The crust is reportedly widespread, except for possibly high elevation north aspects. The surface hoar exists at all elevation bands.2) The early-January persistent weak layer is 100 to 160 cm below the surface. It is composed of surface hoar on sheltered slopes as well as sun crust on steep solar aspects and is found at all elevation bands. 3) Another weak layer buried mid-December consists of a facet/surface hoar/crust combination, which is buried 120 to 180 cm deep. It is most problematic at and below tree line.4) A crust/facet layer from late November is yet another weak layer, which has recently produced very large, destructive avalanches.The wide distribution and ongoing reactivity of these layers suggests that choosing simple terrain free of overhead hazard is the best avoidance strategy.