Northwest Mountains

Yesterday a large natural avalanche ran from light wind-loading, and a smaller slab avalanche was remotely triggered by a human. The sensitivity of the persistent avalanche problem is slowly trending down, but we are not out of the woods yet. Conservative terrain choices and cautious route finding are recommended to manage the dangerous avalanche conditions. You can find reduced avalanche risk on southerly facing slopes and lower elevation terrain. 

Frequent stormy weather since Christmas has produced multiple natural avalanche cycles and recent human-triggered avalanches such as Baxter Basin, West Brush Creek and Mount Axtell.  This avalanche data is a good example of the potentially large and deadly size of recent persistent slab avalanches. 

Initial thinking was that the persistent slab avalanche problem would drop to "possible" in the NW Mountain forecast area by now, and remain "likely" in the SE Mountain forecast area. However, that recent large natural avalanche on Mt Baldy, which released from light wind-loading, doesn't help the big picture move to the "possible" and "stubborn" descriptors for the avalanche problem just yet. The snowpack will need a little more time to adjust to the recent redistribution of snow available for transport by the northerly winds. Another way to look at how the avalanche problem sensitivity is playing out is to avoid defining it by forecast area and instead focus on snowpack depth. Where the snowpack is typically ~50cm to ~90cm, weak layers are often more pronounced and easier for the weight of a human to affect through the thinner slabs. Those snowpack depths are more common in the SE-Mountain forecast area, but of course, those depths exist in some parts of the NW Mountains, and that was probably the case with that Baldy avalanche. Where the snowpack is greater than a meter, weak layers have gained some strength and are harder to affect due to the thicker slabs. 

While dangerous avalanche conditions prevail across the forecast area, some areas offer lower avalanche risk. Recent observations have highlighted good riding and a lower risk of triggering an avalanche on some southerly-facing slopes, such as these observation from the SW side of Purple Ridge, Southern Ruby Range or this example on Mt Baldy. While others have found similar conditions on low-elevation northerly and easterly-facing slopes, thanks to thicker crusts buried in the snowpack at lower elevations. Such as these observations from Elk Creek, Gothic, Washington Gulch and Snoddgrass. 

This fresh weekly summary offers more information on recent snowpack and weather events. 

Upcoming Outreach Events:  

Jan 13 Fireside Chat:  Kim Grant from Silverton Mountain at Zuni West Brewing 5-7 pm