Avalanche Forecast

Fair - Freezing levels are uncertain on Monday

A firmly embedded ridge of high pressure will continue to dominate the region bringing clear skies and light southerly winds throughout the forecast period. An inversion with above freezing alpine temperatures will persist on Sunday, but will give way to a gradual cooling pattern forecast for Monday and Tuesday.

A significant avalanche cycle occurred in the region on Friday as many large loose snow and slab avalanches (size 2-4) were observed. For the most part, the cycle was specific to southeast to southwest aspects in the alpine, with some slides running down to mature forest. Cornice fall was also an issue as many large cornices failed naturally, in some cases triggering a slab on the slope below. There were also a few isolated deep slab avalanches (to size 3.5) on north aspects that failed without cornice fall. It is thought that some of these released at a crust that was formed in October. Expect ongoing avalanche activity with forecast warm alpine temperatures on Sunday.

January was a snowy month in the South Columbia region and average snowpack depths at 1700m are now between 2 and 3m. For the most part, the storm snow is well settled on shaded aspects and riders are gaining increased confidence on steeper terrain. There are, however, several storm interfaces within the top 150cm that operators have been watching, most notably the January 13th interface which had spotty surface hoar. At the bottom of the mid-pack is a surface hoar layer that formed in mid-December. Until Friday these layers were showing very little in the way of reactivity. That changed on Friday as the region experienced above freezing temperatures at alpine elevations due to an inversion and direct solar radiation. As a result, a significant avalanche cycle took place waking up a number of these deeper layers as sun exposed slopes and cornices became moist and weak. Reactivity of deeper layers was not limited to south aspects as some deep failures were observed on north aspects without cornice fall as a trigger. Expect continued weakening of the snowpack with forecast weather on Sunday.