With continued snowfall and strong winds on Tuesday, the hazard will remain elevated.
Avalanche activity will slowly decrease with cooling temperatures, but it will take time for the snowpack to adjust to all the new load.
The Simpson Area avalanche closure zones are CLOSED for avalanche control on Tuesday, December 16th, 2025.
Warm temperatures and more snow/rain will add mass to the slab sitting on top of the mid-pack Nov 22 facet/crust layer and the deeper Nov 13 facet/crust layer. While the likelihood will slowly decrease, we still expect to see large avalanches occur on these layers for the next couple of days.
With continued strong W/SW winds and snowfall we expect to see dry loose avalanches at tree line and above on Tuesday and Wednesday, especially in steep couloirs and gullies. Best to avoid this type of terrain until the conditions improve.
Warm temperatures and ongoing precipitation continue to build storm slabs, while strong SW winds continue to actively redistribute snow into wind slabs in lee terrain at higher elevations. These slabs will remain easy to trigger on Tuesday.
On Monday, wet loose avalanches were observed in steep terrain at lower elevations.
On Sunday and Monday, local ski areas triggered wind slabs up to size 2 in loaded alpine and treeline areas, and persistent slab avalanches up to size 3 on the Nov 17/22 facet/crust layer, with some failing down at the Nov 13 facets/crust layer.
We expect avalanche activity to slow with the cooling temperatures on Tuesday, but the hazard will remain elevated for a few days.
Strong W/SW winds and new snow continue to build storm slabs in the alpine. Below 1900 m, warm air and rain have soaked the past week’s storm snow, with heavy wet snow at valley bottom.
A 50–100 cm slab now sits over the Nov 22 facet layer, which is particularly touchy where it is associated with a sun or temperature crust that persists in some alpine areas. Lower down, the Nov 13 facets/crust layer extends up to ~2100–2300 m.
Treeline snowpack depths range from 60-140 cm.
A cold front on Monday night will cool things down, with freezing levels dropping to valley bottom overnight. On Tuesday, treeline temperatures will stay steady near -6°C with freezing levels rising to 1500 m.
Another 20-30+ cm of snow is expected through Tuesday and Wednesday, with W/SW winds remaining in the moderate to strong range.
