squall

While I always think of a squall as a storm that blows across open water, my Webster's New World dictionary says, "a brief violent windstorm, usually with rain or snow". So, it seems this quick moving storm would qualify as a squall.

It would be an interesting exercise to confabulate a new word that denoted a brief, fast-moving rainstorm that approaches across a cornfield. Maybe I'll do just that, after a few more cups of coffee.