As a ski patroller I'm reading about an increase in Non-Avalanche Snow Immersion Death, (NARSID) which is primarily the result of people skiing, boarding or showshoeing into tree wells and dying, often upside down, due to the inability to escape their over-snow gear.
Usually this happens near ski area groomed trails but is increasingly happening in the backcountry, especially to lone travellers.
When looking for lost out-of-area skiers we are now trained to look carefully both above and BELOW trees as this is the usual location of NARSID situations. Therefore when looking for friends who have trailed behind the group and haven't shown up don't forget to look below trees. In a heavy snowstorm a companion's tracks may be obliterted by the time you find them so don't necessarily count on finding their tracks.