A storm bringing significant snowfall (hopefully!) arrives this weekend, increasing the load over the persistent layers down 20-50cm.
With uncertainty around the storm's track and snowfall amounts, stay alert to changing local conditions.
Over the past week, numerous avalanches have occurred on these layers (20-50cm deep). With incoming snow and strong winds this weekend, the likelihood of both natural and human-triggered avalanches will rise.
Strong alpine winds on Saturday will transport any new and existing surface snow, increasing the chance of sloughing in steep alpine terrain.
Avalanche control along the Sunshine road on Friday produced persistent slab avalanches to size 2.5. A skier-triggered size 2.5 persistent slab was also reported on March 6 on Quartz Hill in the Sunshine backcountry. This slab averaged 50cm but was as deep as 90cm.
On shaded aspects, low-density snow is present, while variable crusts are found on solar aspects. A persistent weak layer of facets (Feb. 22nd/Jan. 30th) lies 20-50cm below the surface, with a faceted mid-pack beneath it. In thin areas, basal facets rest at the snowpack's base. Deeper snowpack areas out West are significantly stronger. Treeline snow depths range from ~75 cm in the east to over 150 cm in the west.
Uncertainty remains about the storm's track and impact.
Saturday: Western regions and Highway 93N may see 5 cm of snow, with little to none in the east. Strong alpine winds expected.
Sunday/Monday: Storm amounts could bring 25-40 cm of snow by Monday morning, mainly West of the divide, and along Highway 93N. Stay tuned.
