Avalanche Forecast

Stormy conditions during the day Wednesday could make it difficult to observe and manage avalanche concerns. Expect the avalanche danger to peak during periods of heavy snowfall and blowing snow. Steer around open slopes greater than 35 degrees at mid and upper elevations where you could trigger an avalanche. Take time to investigate the new snow and how it bonds to the recent crust. Small slope tests and hand pits can give you clues to potential storm slab avalanches. Windy conditions Tuesday night could pile-up snow on lee-slopes at higher elevations forming thicker slabs in those locations.

While this storm doesn’t look like a massive snow producer for Snoqualmie Pass, weather forecasts anticipate enough snow to create new and possibly reactive slabs. The snow will accumulate above a thin and occasionally firm crust formed over MLK weekend. We believe any avalanche concerns should be limited to the storm snow and MLK crust. If you experience rain or very wet snowfall at lower elevations, identify and avoid slopes with new rollerballs or fan-shaped avalanche debris. 

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.