Avalanche Forecast

Wednesday’s avalanche problems will be dynamic and changing throughout the day.

New snow will start to stack up Tuesday night and will fall on a melt-freeze crust that is widespread. It remains to be seen how well new snow will bond to the crust or if sensitive weak layers develop during tonight’s snowfall. Investigate the bond between new snow and the crust below using small test slopes. Look for signs that you could trigger avalanches in the storm snow like heavy snow above light snow, or cracks shooting through the snow. Late morning or early afternoon, as the warm-up begins, will be the most likely time to trigger a storm slab on slopes steeper than 35 degrees on any aspect.

Near and above treeline, winds will be strong enough to rapidly build fresh and sensitive wind slabs on lee aspects. Wind slabs will build above the recent melt-freeze crust and may become large quickly. Look for blowing snow, fresh cornice development and cracks in the snow as signs that you could trigger an avalanche on similar slopes. Avoid leeward slopes steeper than 35 degrees especially midday as the temperatures rise.

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.

As temperatures rise during the day Wednesday and snow eventually turns to rain below 6500’, loose wet avalanches will be easy to trigger. Pay close attention to signs of warming, such as rollerballs of snow, many trees beginning to shed snow or drip water. When you see these signs avoid slopes steeper than 35 degrees, especially when near cliffs, creeks and other terrain traps. Remember that loose wet avalanches are often surprisingly powerful and being caught in even a small on can be dangerous.

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.