whumpf

1. A dull, soft sound as of something hollow collapsing.

plural whumpfs

1. snow sportsThe collapsing of a weak part of the snowpack, accompanied by a whumpf noise and potentially leading to an avalanche.

present singular third person whumpfs · participle present whumpfing · participle past whumpfed · past whumpfed

1. intransitivesnow sportsOf snow: to collapse in this manner.

   Even by the end of the month observers in the Northern and Central Mountains were still reporting collapsing and "whumpfing" snow; conditions that typically disappear in February.

   1999, Colorado Avalanche Information Center, Annual Report (page 10)

   1 more example

   Avoid convex surfaces, especially on lee ridges; this is where slab avalanches most frequently start. If you observe settling or whumpfing of snow as you travel on it, or if the surface cracks and the cracks spread, […]

   2004, Craig Connally, The Mountaineering Handbook, page 48