Winter has begun! Before Thanksgiving the mountains from Virginia Lakes to Bishop were bare of snow. Now there is solid white down below 7000’, with 1-3’+ of coverage above 8000’. Not counting a mid-October storm which brought a couple inches of snow to high elevations which then completely melted away, Thanksgiving was the first real storm of the season. Dropping a foot+ of snow above 9000’, it paved the way for this week’s Wednesday-Thursday storm which dropped another 2-3’ of snow, with highest amounts recorded around Tioga Pass. Snow levels for this storm reached down near 6000’. While the coverage is still thin in the back-country, people have been getting out with their skins and finding some blissful turns in between the occasional rock scrape and bash.
Now for talk on the stability of this new snowpack: Local entities around the Mammoth area reported sensitive storm slab conditions on Thursday morning in steeper mid to upper elevation terrain. Since then Friday brought moderate SW winds to the Mammoth area south toward Bishop for the mid to upper elevations. Significant snow banners could be seen blowing off the higher peaks along HWY 395 until late afternoon on Friday (click here for picture), after which the winds died down considerably. Very fresh evidence of small cornice collapses resulting in small wind slab failures were found just below the ridgetop of the Sherwins on Northerly facing slopes yesterday (Friday) evening (click here for observation).
Much in contrast to last season, the underlying snowpack to the ground this season at this time does not have suspect persistent weak layers lurking, since all of the snow on the ground has fallen so recently. Our biggest avalanche concern for today will be surface instabilities in the form of wind slabs at mid to upper elevations on the leeward sides of ridges and cross loaded steep exposed slopes. These slabs will become more widespread and concerning throughout the day as SW winds pick up and 4-10” of additional snow falls throughout the day.
And again, the coverage is thin! Rocks and tree stumps and logs are lurking just under the surface. Don’t end your season with an injury before it really even begins!