The Collaborative International Dictionary of English v.0.48:
Squall \Squall\ (skw[add]l), n. [Cf. Sw. sqval an impetuous
running of water, sqvalregn a violent shower of rain, sqvala
to stream, to gush.]
A sudden and violent gust of wind often attended with rain or
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 marked in its approach by the clouds. --Totten.