Williams Area

This was an off duty tour to monitor wet snow issues and get a closer look at the large, human-triggered avalanche in a north-facing couloir on Williams Peak. 

The most obvious sign of instability I observed was a wet snowpack.

No formal observations today, just moving through the mountains, listening to occasional wet loose avalanches, and trying to avoid the sun. Cool start to the morning, particularly below the level of the inversion, with things heating up very quickly in the mid to late morning. Snow above 3/10 weak layer had become wet by noon on E and SE aspects and the crusts underneath were already softening. Wet snow problems followed the sun across the sky, with slopes "turning on" to the point of easy human triggering and staying that way. The general sense from today is that we didn't get to widespread large natural avalanches, but that human-triggered wet slides became likely for a good portion of the day. As the sun dropped in the sky, crusts began to reform on E/SE relatively quickly thanks to cool air temps and clear skies. 

There is still a lot of cold, dry snow on shaded slopes. Unfortunately, the northerly winds that blew 3/13 to 3/15 got to some of this snow, forming thin, unreactive (in my travels) wind skins in many locations and eroding others. Still some good skiing to be found, but it is not widespread. 

I've spent a fair bit of time in the Sawtooths over the past 10 days and have gradually been stepping back over the course of this period. The extent of wind loading/slab building in the snow above the 3/10 weak layer and the ongoing meltdown have closed a lot of terrain for me.  The large, frightening avalanche in big fatty appears to have released on a layer of well developed facets buried deeply in the snowpack. (As badly as I wanted to...) I chose not to visit the crown due to the hazard posed by multiple large cornices that threatened the terrain from above. I climbed to above 9,700' in the couloir and turned back there. 

This is the second unusual persistent slab avalanche in very steep terrain that I've observed in the Sawtooths this season. The first was on the shield on Horstmann. Either of these could be considered an outlier, but seeing two hard slabs failing on buried persistent weak layers in this type of terrain is not the normal for the Sawtooths. The snowpack is below average here and has not made its springtime transition. I've built some extra margin into my travel plans to accommodate uncertainty around buried persistent weak layers here and have forced myself to expand the type of terrain that I expect these problems may exist in.