Avalanche Forecast
Regions: Cascades - South West.
Deep new snow combined with strong winds and warming has created dangerous avalanche conditions requiring conservative terrain choices Wednesday. Avoid steep slopes greater than 35 degrees, especially higher terrain that received wind deposited snow where you are likely to trigger avalanches. Avalanches could be large and run far and fast.
Discussion
Snow and Avalanche Discussion
Since Sunday morning an impressive 3-5 ft of new snow has fallen in this zone, with over two feet of new snow in 24 hrs as of Tuesday morning! Much of the storm snow has fallen at cold temperatures with gradual warming and some strong winds Monday night. All this storm snow is sitting on a hard crust and in areas may be poorly bonded with faceted crystals on the crust. This persistent grain type exists in adjacent zones, but there are limited observations in this zone. There were natural and triggered slab releases in the storm snow Tuesday in the Crystal area with some slides running fast and far. It will take some time for these dangerous conditions to stabilize requiring conservative travel.
Snowpack Discussion
New Regional Synopsis coming soon.
Avalanche Problems
Storm Slabs
3- 5 ft or more of recent low-density storm snow is sitting on a hard crust layer. In some areas, buried surface hoar or faceted crystals above the crust are making for very poor bonding. Strong winds and gradual warming have created dangerous slabs to form in many areas, especially steep terrain having been loaded with wind transported snow. This is time to be vigilant choosing conservative terrain. Storm slabs can be avoided by sticking to low angle supported slopes. Cracking or whumphing of the snow is a valuable warning sign that anticipated problems are in your terrain.
Release of a soft cohesive layer (a slab) of new snow that breaks within the storm snow or on the old snow surface. Storm-slab problems typically last between a few hours and few days. Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
You can reduce your risk from Storm Slabs by waiting a day or two after a storm before venturing into steep terrain. Storm slabs are most dangerous on slopes with terrain traps, such as timber, gullies, over cliffs, or terrain features that make it difficult for a rider to escape off the side.
Storm slabs usually stabilize within a few days, and release at or below the trigger point. They exist throughout the terrain, and can be avoided by waiting for the storm snow to stabilize.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Likely
Expected Size: 1 - 1