SLUMP v.
To fall or sink suddenly through or in, when walking on a surface, as on thawing snow or ice, partly frozen ground, a bog, etc., not strong enough to bear the person. The latter walk on a bottomless quag, into which unawares they may slump. Barrow.
SQUALL n.
A sudden violent gust of wind often attended with rain or snow. The gray skirts of a lifting squall. Tennyson. Black squall, a squall attended with dark, heavy clouds. -- Thick squall, a black squall accompanied by rain, hail, sleet, or snow. Totten. -- White squall, a squall which comes unexpectedly, without being m…