A gustnado is a landspout (i.e. a "mini-tornado") that isn't connected to the ambient cloud base (if there is any). Mt Everest, the highest point on Earth, there is nothing "in the way" of colliding winds to form a snow gustnado on the summit. Cumulonimbus clouds can be as high as sixty thousand feet so perhaps even such gustnado could become a landspout (or snowspout). Is there enough area on or near the summit of Mt Everest (or another mountain in the Himalaya or on K2) and the right conditions possible for a snow gustnado or similar whirl spouts to form and persist for some time (and for how long) there?