Avalanche Forecast

Expect widespread wet avalanches. Avoid all avalanche terrain. Very large natural avalanches could run long distances to their historic runouts. You will need to be extra cautious and watch for any overhead avalanche paths where avalanches could run to lower elevation slopes.

Rain falling on dry snow is the perfect combination for large and destructive wet avalanches. Some may be very large and destructive enough to break mature trees. You will definitely see loose wet avalanches and you may see very large wet slabs. Most of the upper snowpack has accumulated since January 10th and has seen little liquid water. This major rain event is the first time these layers will be saturated and weakened. There is much uncertainty around wet slab avalanches and they are very hard to predict. For certain, they can be very large and dangerous.

Release of a cohesive layer of snow (a slab) that is generally moist or wet when the flow of liquid water weakens the bond between the slab and the surface below (snow or ground). They often occur during prolonged warming events and/or rain-on-snow events. Wet Slab avalanches can be very destructive.

Avoid terrain where and when you suspect Wet Slab avalanche activity. Give yourself a wide safety buffer to handle the uncertainty

A Wet Slab avalanche. In this avalanche, the meltwater pooled above a dusty layer of snow. Note all the smaller wet loose avalanches to either side.

Wet slabs occur when there is liquid water in the snowpack, and can release during the first few days of a warming period. Travel early in the day and avoiding avalanche paths when you see pinwheels, roller balls, loose wet avalanches, and during rain-on-snow events.

Warm heavy snow will fall at the highest elevations. Storm slabs will be easy to trigger and could be 2 feet deep. Avalanches at upper elevations could easily entrain wet heavy snow as they run onto lower slopes becoming more dangerous and destructive. You can find a recent crust buried 2-3 feet below the surface that formed around the MLK weekend. This could also serve as a bed surface for avalanches to slide on. Expect drifts to form in exposed terrain at upper elevations from southwesterly winds.

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.