Wet Slab Avalanches:

Warm day and nighttime temperatures and a lack of a substantial freeze will increase the likelihood of Wet Slab Avalanches. This avalanche problem is defined as follows: “Release of a cohesive layer of snow (a slab) caused by meltwater weakening the bond between the slab and an underlying weak layer.” To learn more about wet slabs, click here.

Due to the unpredictable nature of this avalanche problem and the potential for limited warning signs, it’s recommended that you avoid traveling on slopes greater than 30 degrees and limit your time in runout zones, especially on slopes getting hit hard by the sun. If you find yourself sinking to your boot tops in wet snow, it indicates that meltwater is moving freely through the snowpack. Roller balls and pinwheels are visual indicators that the surface snow is getting wet and heavy. Wet Loose avalanches may precede Wet Slabs, but they are more of a surface instability. Wet Slabs can be far more destructive, acting like bulldozers down the mountain.

Wet Slabs often fail around a crust that is lubricated by pooling water. When there are known weak layers in the snowpack (January Facets, Valentine’s Buried Surface Hoar), we can’t rule out large to very large avalanches failing on these weak layers.

Cornices should also be given a wide berth, as they often fail much further back than one would expect. Traveling beneath steep slopes with cornices overhead is a poor idea, especially when it’s this warm.

Once we start seeing a cooling trend and freezing conditions at night, the snowpack will strengthen, and the chances of Wet Slabs will decline.

Removal of the Persistent Slab Problem:

If you read the avalanche forecast published on March 19th, you may notice the removal of the Persistent Slab avalanche problem. The January Facets and the Valentine’s Buried Surface Hoar were the two weak layers we’ve been tracking and testing for some time. Without a reported avalanche on either of these layers since February 25th (approximate) in the Southern Wallowas, we’ve declared these two layers dormant.