Top Fifteen U.S. Tornado Outbreaks

There is no doubt that the April 3-4, 1974 tornado outbreak remains the greatest 24-hour tornado outbreak in recorded U.S. history.

But, there are many other tornado outbreaks that are noteworthy unto themselves. Until 2004, there was no absolute scale by which to rate such outbreaks. Typically meteorologists use some combination of fatalities, number of twisters, damage, and area affected to classify these. The NWS office in Milwaukee, WI classified the top 25 outbreaks by "severity," while the Tornado Project classified the top 10 individual tornadoes by fatalities. Then Russell S. Schneider, Joseph T. Schaefer, and Harold E. Brooks of NOAA's (National Oceanic and Atmospheric Administration) Storm Center in Norman, OK and Greg Forbes of The Weather Channel developed two more objective systems for assessing outbreak events.

Schneider et al, using a definition of a "tornado day" and the distribution of tornado events across the spectrum of the Fujita Scale, arrived at an outbreak category scale ranging from 1 to 6. The higher the number of tornadoes and the greater number of more powerful tornadoes, the higher the outbreak value.

While this may appear to ignore the obvious - casualties - it really doesn't. The authors noted that, "...preliminary data suggest that while only about 3.5 percent of all days can be classified as Tornado Outbreak Days (Cat. 1-6), they account for over 80 percent of all tornado fatalities. Further, Major Tornado Outbreaks (Cat. 3-6) are observed on an average of 1.6 days per year (less than 0.5 percent of days), but account for nearly 50 percent of all fatalities."

This means that if a day can be classified as an outbreak day, fatalities likely occurred.

Forbes, used a different approach and used a suite of 11 criteria (including number of more intense tornadoes, deaths, injuries, number of killer tornadoes and total path length).

Not to be outdone (LOL), I went back into the historical record (see links within content piece) to rate my top 15 tornado outbreaks (which obviously includes the April 3-4, 1974 outbreak). I was a bit more generous and did not lock myself into a calendar day. Instead I let the weather pattern define the outbreak. I also wanted to look at those outbreaks with at least 30 tornadoes (which would rate the outbreak as category 6). I ignored situations in which hurricanes generated large numbers of tornadoes because these situations typically do not produce long-tracked deadly twisters. Further, since both previously mentioned papers were published, a new Enhanced Fujita Scale has been introduced and is being used to classify tornadoes. This will require that past research and classification systems be updated.

The actual number of tornadoes and casualties may not match all documented reports since the event climatology is always under scrutiny and review. Still, the numbers shown in the following are well within the bounds of being category 6 on the outbreak scale.

I've listed what I consider to be my top 15 outbreaks below (along with links for those of you who want to know more). Although I ordered these events based on fatalities, simply being in the top 15, is noteworthy enough. Damage totals (not available/reliable for all events) have NOT been adjusted for inflation.

Finally, recognize that due to improvements in technology, warning dissemination and public awareness, the death toll in many of the more recent outbreaks is likely a fraction of what it would have been back in 1950, the start of the Nation's tornado warning program.

01. SUPER OUTBREAK
* April 3-4, 1974
* Large part of the eastern U.S.
* 148 tornadoes in 24 hours
* more than 330 deaths
* 6,142 injuries
* Damage $600+ million

02. MAY 2007 CENTRAL PLAINS OUTBREAK
* May 4-6, 2007
* South Dakota, Nebraska, Kansas, Iowa and Oklahoma
* Approximately 120 tornadoes during a two-day period (90 tornadoes on May 5-6, 2007; Greensburg, KS struck by an EF5 tornado on May 4)
* 14 deaths
* afternoon until slightly past midnight

03. NOVEMBER OUTBREAK
* November 21-23, 1992
* Southeast Texas to Mid-Atlantic and Ohio Valley
* 94 tornadoes
* 26 deaths
* 641 injuries
* Damage $291 million
* Began 1:30 pm Nov. 21 , Ended 7:25 am Nov. 23

04. VETERAN'S DAY WEEKEND OUTBREAK
* November 9-11, 2002
* Indiana, Ohio, Pennsylvania south to Mississippi, Alabama, Georgia
* 92 tornadoes
* 35 deaths
* 200 injuries
* 1:00PM-2:00AM
* Highest November deaths on record

05. MAY OUTBREAK
* May 4, 2003
* Kansas, Missouri, Tennessee
* 94 tornadoes
* 37 deaths
* 2:00pm - 10:00pm
* Period from May 4-10 - 393 tornadoes, 39 deaths, record $2.2 billion in damage
* Most active tornado week on record (surpassing May 12-18, 1995 when 171 twisters occurred)
* All of May 2003, total of 562 tornadoes, average is 229.

06. SUPER TUESDAY TORNADO OUTBREAK
* February 5-6, 2008 (12-hour period)
* 9-state region from Kentucky southward to Alabama and Arkansas eastward to Tennessee
* 87 tornadoes (31 in Tennessee)
* 57 deaths in four states
* Second largest February tornado outbreak since 1950 (beginning year of official tornado database) in terms of
fatalities and the largest since May 31, 1985
* Five violent Enhanced Fujita (EF) Scale 4 tornadoes reported; two each in Tennessee and Alabama, and one in Arkansas. The EF4 tornado in Arkansas had a remarkable 122-mile continuous damage path; this was the longest path length of a tornado in the state since at least 1950.
* A deadly EF3 tornado that touched down northeast of Nashville, Tennessee, carved a 51- mile path of destruction claiming 22 lives. This was the deadliest tornado in the United States since a tornado in Evansville, Indiana, in November 2005 killed 25 people.

07. OKLAHOMA OUTBREAK
* May 3, 1999
* Oklahoma, Kansas
* 70 tornadoes (50 in OK), largest outbreak in OK on record.
* 55 deaths
* 2000 injuries
* Damage $2 billion
* 2:00pm - 10:00pm

08. ENIGMA OUTBREAK
* February 19, 1884
* Southeast U.S from Mississippi to Virginia
* 60 tornadoes
* 420 deaths (but ranges from 182 to 1200, hence the term "enigma")
* Damage $4 million in Georgia alone
* 11:00 am - 11:00 pm

09. PLAINS OUTBREAK
* April 26, 1991
* Texas, Oklahoma, Kansas, Nebraska
* 54 tornadoes
* 21 deaths (13 in Andover, KS)
* 308 injuries
* Damage $277+ million
* Portable Doppler radar measured wind speeds in Red Rock, OK tornado at 286 mph.
* 2:30 pm - 11:00 pm

10. NORTHERN ILLINOIS OUTBREAK
* April 21, 1967
* Especially Northern Illinois, also Missouri, Iowa, Lower Michigan
* 52 tornadoes
* 58 deaths
* 1109 injuries
* Damage $100+ million
* 12:30 pm - 9:00 pm

11. PALM SUNDAY OUTBREAK
* April 11-12, 1965
* Midwest/Great Lakes states
* 51 tornadoes (6 in Wisconsin)
* 260 deaths (3 in Wisconsin)
* 3148 injuries (65 in Wisconsin)
* Damage $200+ million
* 1:00 pm - 1:00 am

12. UPPER MIDWEST OUTBREAK
* June 7-8, 1984
* Missouri, Iowa, Minnesota, Wisconsin
* 42 tornadoes (9 in Wisconsin)
* 13 deaths (9 in Barneveld, WI - hit at 12:47 am June 8)
* 319 injuries (202 in Wisconsin)
* Damage $100+ million
* 2:00 pm - 2:00 am

13. DEEP SOUTH OUTBREAK
* March 21-22, 1932
* Deep South (especially Alabama)
* 33 tornadoes
* 334 deaths (268 of these in Alabama)
* Damage $5 million
* 3:00 pm - 1:00 am

14. JANUARY OUTBREAK (MIDWEST)
* January 24, 1967
* Iowa, Missouri, Illinois, Wisconsin
* 30 tornadoes (1 in Wisconsin)
* 7 deaths
* 268 injuries
* Damage $100+ million
* 11:45 am - 8:45 pm

15. UTICA, INDIANA OUTBREAK
* April 20, 2004
* Mostly Illinois and Indiana
* 30 tornadoes
* 8 deaths
* 2:00pm - 9:00pm