Mammoth Area

I went to see storm instabilities in the Mammoth Lakes Basin.

• I didn't see any recent natural avalanches. I did trigger some small dry loose avalanches. These were bigger on north and east aspects, where more new snow has accumulated and is sitting on snow that existed before these storms. It was hard to find wind slabs and I couldn't trigger a slab avalanche in the terrain I was in, but I did get shooting cracks on some of the features most prone to wind-drifting.
• The new snow is mostly cohesionless and right-side-up, except where it was stiffened by the wind last night. The places I got cracking, the cracks broke down to a storm interface, not on the old melt-freeze snow.
• It was less windy than I expected until right at the end of my day, when winds and snowfall seemed to increase considerably.

Visibility on the Crest was poor, and it was hard to spot wind slabs. Combining those observations with the few shooting cracks I got in drifted snow, I decided to manage my sluffs on smaller slopes near and below treeline rather than go looking for trouble in leeward alpine couloirs.

I got shooting cracks in wind-drifted snow on only the most favored features. I triggered small dry loose avalanches on north and east aspects near and below treeline and got at least a little surface snow to sluff on almost every aspect.

The storm snow was mostly right-side-up, except where the wind had drifted it. In those few favored places, I got shooting cracks or triggered very tiny, baby wind slabs.

• Slabs were 1 finger-to 4 finger (from top to bottom), and they were breaking at the interface (Fist hard) between yesterday's graupelly snow and last night's storm snow about 10 cm above the old melt-freeze snow.  I found slabs up to 40 cm thick; they just didn't stretch far across the slopes I traveled on.
• It seemed like today's snow was covering and masking wind slabs that formed last night, making them harder to spot by shape or texture. It didn't help that they were also pretty isolated and hard to find.

The new snowfall today was convective and a mix of rimed snowflakes and graupel. Below treeline and on solar aspects, the storm snow was just covering obstacles and the snowpack was very thin. I had to ski very carefully and still scraped up my bases on rocks and logs on my way down at lower elevations.