Avalanche Forecast

If you travel above the rain-snow line, expect warm temperatures and strong winds to create upside-down storm snow. Temperatures will continue to warm as precipitation shuts off from south to north during the morning hours, leading to the potential for some natural avalanche activity near or above treeline. Heed the warning signs of natural avalanche activity if you observe it. Steer around any slope greater than 35 degrees and limit your exposure to slopes where avalanches could run and stop, particularly during periods of precipitation. 

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.

The surface snow will experience a big transition as snow turns to rain, and quickly create unstable wet surface snow. Expect natural loose avalanches when this occurs. As you encounter rain on snow, new rollerballs, or fan-shaped avalanche debris, avoid sloped greater than 35 degrees and steer around places where avalanches could run and stop. Avalanches will be larger in the near treeline band where more recent snow fell. At lower elevations, there generally is not enough snow above the crust to present a significant avalanche threat.

Release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. They generally move slowly, but can contain enough mass to cause significant damage to trees, cars or buildings. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.

Travel when the snow surface is colder and stronger. Plan your trips to avoid crossing on or under very steep slopes in the afternoon. Move to colder, shadier slopes once the snow surface turns slushly. Avoid steep, sunlit slopes above terrain traps, cliffs areas and long sustained steep pitches.

Several loose wet avalanches, and lots of pinwheels and roller balls.

Loose wet avalanches occur where water is running through the snowpack, and release at or below the trigger point. Avoid terrain traps such as cliffs, gullies, or tree wells. Exit avalanche terrain when you see pinwheels, roller balls, a slushy surface, or during rain-on-snow events.