|A squall line is a system of thunderstorms
that have formed into a line.
This often occurs ahead of a cold front, where
wind shear combined with unusually widespread lifting
of the lower atmosphere causes convection
to become arranged in a banded structure. The line itself will be relatively narrow, and
it is usually followed by a much larger area of ligh rain trailing behind it. While a squall line can have heavy rain, high winds, and small hail,
tornadoes and large hail are more commonly
associated with isolated thunderstorms, not squall lines.