North Columbia

Warm air and sunny skies persist at higher elevations. The amount of warming and its influence on the snowpack is uncertain. Travel conservatively and observe for signs of snowpack warming -- conditions may change rapidly over the day.

Moderate - Freezing levels are uncertain

SUNDAY NIGHT: Mostly clear skies, inversion conditions with above-freezing layer between 1800 m and 2300 m.MONDAY: Clear skies, light west winds, alpine temperature -1 to 2 C, inversion conditions with above-freezing layer between 1800 m and 2500 m.TUESDAY: Clear skies, light southwest winds, alpine temperature 0 C, inversion conditions with above-freezing layer between 2100 m and 2500 m.WEDNESDAY: Partly cloudy skies, light southwest winds, alpine temperature -4 C, freezing level below valley bottom.

Numerous storm slab avalanches were triggered naturally on Sunday, likely due to warming and solar input. They were large (size 2 to 3), released on all aspects, and generally in treeline and alpine terrain.A few wind slab avalanches were triggered naturally, by skiers, and by explosives on Saturday. They were small to large (size 1.5 to 2.5), on all aspects, and generally at treeline and alpine elevations. See here for a recent report.For the weekend, the likelihood of triggering slab avalanches may increase due to the substantial amount of warming expected around treeline and alpine elevations. Also watch out in thin snowpack areas, where the likelihood of triggering deeper layers is the highest. See here for a recent example.

Warm air temperatures and sunny skies at higher elevations may impact the snow surface. You may find dry or moist snow depending on how warm it gets. On south aspects, you will likely find a sun crust. The warm air may produce touchy storm slabs at all elevations and particularly on southerly aspects where the greatest amount of warming is expected. Wind slabs may still linger in lee and cross-loaded terrain features in alpine and exposed treeline terrain.The middle and lower portions of the snowpack are generally well-settled and strong. However, there still remain a few deeper weaknesses in the snowpack around treeline and alpine elevations. Professionals are still tracking a layer around 150 to 200 cm deep, composed of sugary faceted grains, feathery surface hoar, and a sun crust. The base of the snowpack may also still be composed of weak faceted grains. These layers would most likely be triggered by humans in areas where the snowpack is shallow. The likelihood of triggering these layers may increase with the warm air expected to last until Tuesday.