Northwest Mountains

Today's snowfall is not expected to have a significant impact on avalanche conditions with only a couple of inches forecasted.  Moderate southwest winds, then transitioning to the northwest by afternoon, will transport any new snow to the leeward side of terrain features.  The most concerning terrain features will be locations with previous or active wind-loading that face west, north, east, and some upper elevation southeasterly aspects.  Signs of instability have been diminishing, but they continue to trickle nearly every day.  Continue to exercise caution and restraint; it remains possible for you to trigger a dangerous avalanche today on slopes steeper than about 35 degrees.  If you find around 6 inches or more of new snow then you should expect that the avalanche hazard is trending to the CONSIDERABLE rating.  Uncertainty about the snowpack is best managed with simple terrain choices that are lower-angled.  Remember that you can trigger avalanches remotely from below or adjacent terrain.   

For today, there are two important things to discuss.  The first being, the change to MODERATE for the Southeast Mountains, and the second, the impact today's snowfall could potentially have on conditions if snow production exceeds forecasted amounts.  

The danger rating has been dropped to MODERATE for all elevations in the Southeast Mountains.  As time passes, slabs have become less reactive and are showing fewer signs of instability however, you can still trigger a dangerous avalanche.  At the lowest elevations, without wind effect, slabs are slowly faceting and losing strength, but anticipate that if the snowpack provides enough support for enjoyable turns on skis, board, or snow machining then there is enough slab present to produce avalanches.  The most concerning terrain features are found at upper elevations where westerly winds over the past week have drifted snow.  Upper elevation slopes with an easterly component are the bullseye for finding trouble particularly slopes below ridgelines or features with large fetches where the wind was able to move substantial amounts of snow.  To see an example of this take a look at a remotely-triggered avalanche from two days ago near West Brush Creek.   This avalanche was large enough to snap small trees and bury a person, clearly life-threatening.  Even though the sensitivity of the Persistent Slab problem in the Southeast Mountains is improving, your best terrain choices will be lower-angled slopes that are not beneath or connected to steeper slopes on aspects highlighted by the Persistent Slab rose.  As mountain travelers, we can not outsmart the snowpack, only examine it, accept it, and utilize our terrain choices to minimize risk.  Disciplined terrain selection is the name of the game.  This mindset applies to both the Southeast and Northwest Mountains.

Now for today's weather.  This storm system does not look impressive with only a few inches expected, but given that our snowpack has only been showing small, incremental improvements, it may not take much of a storm to quickly increase the danger.  In the Bottom Line, it was mentioned that if you find 6 inches or more of new snow, then you should expect the avalanche danger to be trending towards CONSIDERABLE.  The first features of concern would be on drifted terrain features where moderate to strong winds drift the new snow followed by sheltered terrain features.  Avalanches could break in basal weak layers or towards the top of the snowpack.  Take a look at this observation and accompanying snow profile photo to get a clearer picture of weak layers on shaded, below treeline slopes.   The past two weeks have shown that the snowpack is intolerant of modest loading events and until the snowpack presents evidence otherwise, we should expect similar results.  To be clear this is conditional, current snowfall forecasts do not look to be enough to cross the tipping point of increasing the danger, but with the slim margins that the snowpack is currently providing, it is prudent to convey this message.  It is not typical for 6ish inches of snow to have a significant impact on the overall avalanche hazard, but this winter is not typical.