A bomb cyclone occurs when there is a rapid pressure drop, with a decrease of at least 24 millibars -- a measure of atmospheric pressure -- over 24 hours. JUST WATCHED Just what exactly is a 'bomb cyclone'? Replay More Videos ... MUST WATCH Just what exactly is a 'bomb cyclone'? Wyoming closed state offices in Cheyenne, while South Dakota's governor ordered state offices closed in 39 central and western counties because of the storm. On Wednesday, 100 vehicles were involved in an accident on Interstate 25 near Wellington, Colorado, according to Wellington Fire Protection.

Source: CNN March 14, 2019 08:02 UTC