Tornado outbreak sequence of May 2004

Tornado outbreak sequence of May 2004
	Radar image of the supercell that spawned the Hallam, Nebraska, tornado.
Type	Tornado outbreak
Duration	May 21, 2004 – May 31, 2004
Highest winds	207–260 mph (333–418 km/h) (Hallam, Nebraska on May 22);
Tornadoes; confirmed	389 (33 significant)
Max. rating1	F4 tornado
Duration of; tornado outbreak2	11 days
Fatalities	7 fatalities, 123 injuries
Damage	$175 million (May 22); $65 million (May 29–31)
Areas affected	Central, Southern, and Eastern United States, Ontario
	Part of the tornado outbreaks of 2004; 1Most severe tornado damage; see Fujita scale; 2Time from first tornado to last tornado

The tornado outbreak sequence of May 2004 was a series of tornado outbreaks that affected much of southern Ontario, Canada, the Central and Southern United States from east of the Rockies to the Mid-Atlantic States from May 21 to May 31, 2004. Particularly hard hit were the central Plains from Missouri to Iowa and the Ohio Valley. The Central Plains were hit by two significant outbreaks on May 22 and May 24, the first outbreak of which produced a very large and violent F4 tornado in Hallam, Nebraska on May 22. The Ohio Valley was affected by one of the largest tornado outbreaks ever during the Memorial Day weekend on May 29–30.

Seven people were killed in four states during the entire event. In all, 389 tornadoes were confirmed over an 11-day period – close to the number of tornadoes in the May 2003 tornado outbreak sequence which affected more or less the same area. However, the 2003 outbreak sequence produced several more destructive and violent tornadoes and had a much higher death toll than in May 2004.