Noun
English Wikipedia has an article on:squall lineWikipedia
squall line (plural squall lines)
(meteorology) A line of thunderstorms, hundreds of miles long, with squalls at the advancing edge.
The squall line seems to be moving slower rather than faster so while forecasters can’t pinpoint the exact time Lowndes County will see the squall line, they do feel confident that it will not arrive prior to the 5 p.m. window. Source: Internet