South facing slopes are my weakness as a snow and avalanche worker. I have the least experience with this side of the compass. Maybe it's why I am so curious about this interface. With that in mind I wanted to check out the weak layer of the natural avalanche in Mill A.

This avalanche released naturally January 24th on a south east facing slope at 9500' in elevation and almost identical to the avalanche one ridge over (White Snake)

For what it's worth - It appears that the Jan 14th melt/freeze crust with faceted grains underneath was in fact the culprit in this avalanche. This marks the 3rd location where we have seen and noted the facet/crust combo. Brighton Backside, Flaffstaff Ridge, and Gobblers. My guess is that it is present on most of the south aspects. This crust/facet combo varies in depth and strength throughout the range.

I have lots of questions about this interface, for example - Why is the weak layer stronger at Brighton than mid Big Cottonwood Canyon? It was the surface snow from January 9th - 13th that was subjected to strong temperature gradients and faceted. A sunny day formed a melt freeze crust that was buried and preserved on the 14th. This tells us it has nothing to do with the overall depth of the snowpack (like early season facets, depth is everything). The same surface snow was at Gobblers, Brighton and Flagstaff - wouldn't all the weak surface snow be somewhat the same? Why is Brighton so different from Gobblers? Not sure I know how to answer this question, I do have my theories. However, the bottom line is that it is producing avalanches and that's bulls eye information we can't ignore.

It's hard to predict the behavior of the crust/facet combo, but it's easy to find - all you have to do is take your shovel out and dig. I would imagine it won't be the last avalanche we see at this interface, especially with heavy snow and wind in the forecast. Here in the Wasatch we are usually pretty safe to jump into the steep south facing slopes right after a storm - However, this year is a bit different and we need to watch the slope angles where this weakness is found.