Northwest Mountains

Slabs 2 to 4 feet thick on average, are resting over widespread weak layers around the compass. These slabs are becoming increasingly difficult to human trigger with each passing day, but the consequences if triggered remain severe. Obvious signs of instability have become rare, and the poor snowpack structure will not be revealed unless you dig into the snowpack. Careful snowpack evaluation is required to identify how the current avalanche problem exists in the terrain you are traveling in. The most likely areas to trigger an avalanche are where the snowpack thins near rock outcrops, or in wind-affected terrain for example. 

Mild weather over the last week has allowed the upper snowpack to gain strength. If you stepped into the snow last Thursday, you would have sunk up to your waist or deeper. Now if you step into the snow you will often only sink up to your boot tops. This strong snow is the slab that is resting above wide-spread weak layers formed during the December and early January drought. In most areas, those weak layers have not gained any notable strength and remain just as ugly as when they were first buried. The weight of a human is held up by that strong slab and this has made it more difficult to affect the weak layers below. That is why we are seeing fewer obvious signs of instability and a downturn in avalanche activity. Do not be fooled into thinking the avalanche problem has gone away, or let yourself become complacent by a decrease in those red flags. 

The persistent slab avalanche problem becomes more likely to trigger where that strong slab thins and it is easier to affect the weak layer below. Thinner slabs are more common in the SE Mountain Forcast area, like in this recent observation on Cement Mountain that noted a widespread collapsing snowpack. In the NW Mountain forecast area, the slab is more often thick, and areas where those slabs taper down and become thin are the most likely trigger points, such as this remotely triggered avalanche on Mt Baldy last week. 

The several hundred avalanches that occurred in the last couple of weeks have also created a patchwork in the location of the avalanche problem, as some slopes no longer have a slab above the weak layer. 

If you are riding in avalanche terrain, there is a lot to put together in the avalanche equation. Such as: Is the persistent slab avalanche structure present? How thick is the slab and how likely are you to trigger? What is the consequence of a triggered avalanche in the terrain? If you are stepping out in your terrain choices from run to run or day to day, be asking and trying to answer those questions. Otherwise, you may be traveling blindly through a field of land mines. If you start to answer those questions and can start identifying trends, then you will find areas with fewer land mines, or discover techniques to travel around those land mines.