Northwest Mountains

The threat of human-triggered avalanches lingers where you find cohesive slabs resting above weak snow.  You can potentially find trouble at all elevations, but the largest and most dangerous avalanches are near and above treeline where winds have formed thick, cohesive slabs.  Your safest terrain options are lower-angled slopes around 30 degrees or less.  If you choose to enter avalanche terrain, then pick smaller slopes that offer reduced consequences like those without trees, cliffs, or gullies in the runout.

The danger rating for below treeline slopes has been dropped to LOW for the Southeast Mountains but remains at MODERATE for the Northwest Mountains.  LOW danger doesn't imply there is NO avalanche danger.  To be more a bit more precise, the Persistent Slab problem below treeline has slowly, over two weeks of cold and dry weather, become isolated across the terrain due to slabs faceting away.  Most slabs existed on north and east aspects, so if you were to find this isolated problem expect it to be on those aspects.  For terrain on Mount Emmons, Anthracite Mesa, and Snodgrass (terrain in SE mountains that directly borders NW mountains), slabs were a bit more substantial, to begin with, due to increased snowfall thus are more likely to linger a bit longer.  Below treeline slopes that received a bit of wind effect at some point may also hold on to slabs a bit longer.  The highest elevation band for below treeline slopes just below 11,000' maybe another place slabs could linger a bit longer.  If you are feeling slabs when pole probing through the terrain, you may be near a place where you can still find the isolated Persistent Slab problem below treeline in the Southeast Mountains.  Collapsing is a sign that the Persistent Slab structure still exists.  The expected size of an isolated slab avalanche in this terrain is small, but even small avalanches can pose a hazard if terrain traps are involved. 

The last loading event was about 6 days ago.  This loading event largely impacted leeward terrain features at upper elevations due to northerly winds transporting new snow with the most snow falling in the Northwest Mountains with up to 7 inches accumulated near Irwin and Paradise Divide.  Below treeline slopes received very little snow from this event, only a few inches.  These factors make previously drifted near and above treeline features the most concerning and suspect.  Here are two observations from this loading event with a couple of skier-triggered avalanches and a large, natural avalanche.  Stability tests and signs of instability are showing improvement, but the evidence does not suggest that slabs are unreactive to the weight of a person or machine.  Predicting which slopes hang in the balance and which slopes have reached a temporary equilibrium is a challenging and complex decision.  A good way to look at decision making for traveling on upper elevation slopes, where you should be certain that slabs exist, is to think about consequences and less about likelihood.  Understanding the likelihood of triggering an avalanche on a given leeward slope remains a bit of a guessing game whereas judging the consequences of triggering an avalanche is a bit more straightforward.  If you are uncertain about the chances of triggering an avalanche on near and above treeline slopes then consider the consequences of being wrong.  Are there terrain traps like trees, cliffs, or gullies?  Is the slope large and offer the potential for a long-running avalanche?  Your best tool for managing uncertainty is with thoughtful terrain selection that leaves room for error.