Avalanche Forecast

Over a foot of fresh snow could accumulate by Sunday afternoon forming fresh storm slabs. The most dangerous slopes are at upper elevations where avalanches could be large. Stay off of steep slopes near and above treeline where the wind has drifted thick slabs. You can trigger avalanches on any slope 35 degrees and steeper where the new snow is poorly bonded. If you choose to travel in avalanche terrain, carefully evaluate the new snow.

Recent avalanches are the best indicator that you should avoid avalanche terrain. Use small, inconsequential slopes and tests to check if the storm snow will slide. A variety of old surfaces, from soft snow to crust, have created variable bond between the storm snow and older layers.

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.

You could trigger Deep Persistent Slabs in the eastern portion of the zone and on steep, shaded slopes facing west through north through east. While these avalanches are generally difficult to trigger, they are also hard to predict. If you initiate an avalanche in the storm snow in wrong spot, it could result in a very large and dangerous avalanche.

The best way to reduce the risk of this is a low likelihood, high consequence scenario is to minimize your exposure to terrain capable of producing large avalanches:

-Limit the amount of time you spend on or near slopes 35 degrees and steeper.

-Put an extra buffer of terrain between where you travel and where avalanches could start.

-Stay well out from under large avalanche paths and identify safer areas to stop and regroup.

Release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer, deep in the snowpack or near the ground. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage. They commonly develop when Persistent Slabs become more deeply buried over time.

Deep Persistent Slabs avalanches can be destructive and deadly events that can take months to stabilize. You can trigger them from well down in the avalanche path, and after dozens of tracks have crossed the slope.

A snowboarder triggered this Deep Persistent Slab near treeline, well down in the path.

Deep, persistent slabs are destructive and deadly events that can take months to stabilize. You can triggered them from well down in the avalanche path, and after dozens of tracks have crossed the slope. Give yourself a wide safety buffer to handle the uncertainty, potentially for the remainder of the season.