10 Worst U.S. Tornado Outbreaks

Comparing the Worst Outbreaks

There are many ways to compare tornado outbreaks. You can simply look at raw tornado or fatality counts for a quick look. But how do you truly dig down to answer the question, "Which are the worst U.S. tornado outbreaks?"

TWC Severe Weather Expert Dr. Greg Forbes (Facebook | Twitter) examined 11 parameters to rank the severity of U.S. tornado outbreaks from 1950 through November 2012. 

These parameters include not only deaths and tornado counts, but also number of violent tornadoes, killer tornadoes, damage amounts, total tornado path length, number of wide-track tornadoes, number of states affected, number of tornadoes per hour and number of injuries.

These values were combined into a "Forbes Impact Index", with a maximum value of 100.

To be clear, we are considering tornado outbreaks, not necessarily one singular, destructive tornado, such as, for example, Greensburg, Kan. (May 2007).

Let's kickoff our top 10 worst outbreak list with a pair of classic outbreaks in the Southern Plains.

#10: (tie) Oklahoma, etc. (May 24-26, 2011) and Paris/Broken Bow (April 2-3, 1982)Forbes Impact Index:  22

Fast Facts

• May 24-26, 2011:  186 tornadoes, 4 of which were violent (EF4/EF5)
• EF5 tornado tore a 75-mile path across central Oklahoma on May 24, 2011
• 18 killed on May 24, 2011 in Okla., Kan. and Ark.
• Apr, 2-3, 1982:  56 tornadoes
• Apr, 2-3, 1982:  30 killed, 383 injured

Wrapping up a stunningly deadly April and May in 2011 was one final outbreak that, while hitting the Southern Plains hardest, stretched into the Ohio Valley, Tennessee Valley and Northeast.

The signature tornado from this outbreak was a massive EF5 "wedge" tornado that tore through areas to the west, northwest and north of Oklahoma City on May 24.  As a sidelight, the EF5 rating was assigned based on measurements from a University of Oklahoma mobile Doppler radar.  

This EF5 tornado claimed 7 lives in central Oklahoma, while injuring 112.  Additional killer tornadoes touched down in Logan, Grady and Major Counties.  Other killer tornadoes in this outbreak spun through Stafford County, Kan., as well as Franklin and Johnson Counties, Ark.  

(MORE:  Photos | An Unusual Tornado)

The April 1982 tornado outbreak affected areas from north Texas to Illinois, but, as most outbreaks, was marked by several deadly and destructive tornadoes.

An F4 tornado leveled Paris, Texas killing 10 and injuring 170.  

Reaching a width of up to 1.5 miles wide, an F5 tornado carved out a 53-mile long path through McCurtain and Choctaw Counties in southeast Oklahoma.  This was the first F5 in the United States in almost five years, since the Birmingham, Ala. Apr. 4, 1977 tornado.  

Another F4 tornado carved a path in southwest Arkansas south of DeQueen and Nashville, ending near Blevins, claiming three lives.  

Our next outbreak corresponded to a fairly important election day.

#8:  "Super Tuesday Outbreak" (Feb. 5-6, 2008)Forbes Impact Index:  23

Fast Facts

• Record February U.S. tornado outbreak:  86 tornadoes, 10 states
• Deadliest U.S. tornado outbreak since May 31, 1985:  57 killed
• Total damage: over $1 billion

February isn't a typically active severe weather month. Typically, cold air dominates the eastern two-thirds of the nation, squashing the tornado threat in the Deep South. Some Februaries only manage around a dozen tornadoes for the entire month, when cold air is particularly dominant in the East.

But that's just an average. A sharp dip in the jet stream slid into the Plains states on "Super Tuesday". Ahead of this powerhouse so-called trough, temperatures warmed into the 70s and even low 80s in the Lower Mississippi and Tennessee Valleys, accompanied by an almost muggy air mass, certainly by early February standards.

What followed was the largest U.S. February tornado outbreak on record. Five tornadoes were rated EF4. One of these tracked an astonishing 122 miles across Arkansas, the longest tornado path of record in that state. Another EF4 tornado hit Jackson, Tenn., inflicting damage on every building at Union University.  This was the third F4/EF4 tornado to hit the city in 10 years.

Super Tuesday 2008 was the deadliest tornado outbreak in both Kentucky (7 killed) and Tennessee (31 killed) since the April 1974 "Super Outbreak".

Next, we visit an infamous tornado as part of one tornado outbreak.

#6: (tie) Joplin, Mo. (2011) and Union City, Okla. (1973)Forbes Impact Index:  24

Fast Facts

• May 22, 2011:  48 tornadoes, including Joplin EF5
• Joplin, Mo. was deadliest U.S. tornado since 1947 (161 deaths)
• Estimated damage in Joplin: $2.8 billion (Costliest single tornado in U.S.)
• May 26-29, 1973 outbreak:  99 tornadoes, 22 deaths

The day's first killer tornado on May 22, 2011 was not in Joplin, Mo.

An EF1 tornado tore through the west and north sides of the Minneapolis metro that afternoon.  One person was killed along the tornado's six-mile path through north Minneapolis, St. Louis Park, Golden Valley, Fridley, Mounds View and Blaine.  

Then all hell broke loose much farther south. 

A mile-wide EF5 tornado with peak winds estimated over 200 mph damaged 75% of the city of Joplin, Mo., rendering neighborhoods unrecognizable and severely damaging both St. John's Hospital and Joplin High School.

(MORE:  One of Worst Tornadoes | Photos | Before/after)

Joplin and Minneapolis were just two of 48 tornadoes which touched down in the Midwest on May 22, 2011.  

The late May 1973 outbreak is not as well known for its total impact, despite its statistics (99 tornadoes, 22 killed from 8 killer tornadoes) as it is for a famous tornado observed several days earlier.

On May 24, 1973, a tornado mauled through the town of Union City, Okla.  

For the first time, researchers from the National Severe Storms Laboratory in Norman, Okla. were able to position storm chasers for an intercept of this destructive tornado, documenting the entire life cycle of this storm.  This is something we may take for granted today in an era of streaming video, social media and cable storm chase shows.

The NSSL research meteorologists later found rotation aloft before the tornado touched down, establishing a bedrock nowcasting technique still used today in most tornadic supercells.

Speaking of Oklahoma, our #5 worst tornado outbreak hammered the Sooner State almost 26 years later.

#5:  Oklahoma City Metro (Moore) (May 3, 1999)Forbes Impact Index:  26

Fast Facts

• Record Oklahoma tornado outbreak:  61 tornadoes
• 55 killed, 40 in Oklahoma
• Total damage: $1.6 billion

While supercell thunderstorms spawned tornadoes in 8 states, including an F4 striking the south side of Wichita, Kan. claiming 6 lives, it was a monster F5 tornado that stole most of the headlines.

A tornado just northeast of Chickasha, Okla. quickly strengthened and grew into a violent tornado as it carved a swath through Bridge Creek and Moore. This was the first F5 tornado on record to hit the Oklahoma City metro. The "Doppler on Wheels" research radar measured a wind speed of 301 mph about 100 feet above the ground in that mammoth tornado.

This single tornado was responsible for $1 billion in damage and 36 fatalities. Three were killed seeking shelter under or near highway overpasses. Over 2300 homes were destroyed and over 7500 were damaged in the Sooner State alone.

Next, you may not think one of our worst tornado outbreaks has occurred in....November.

#4:  Houston to Carolinas Outbreak (Nov. 21-23, 1992)Forbes Impact Index:  30

Fast Facts

• Record November tornado outbreak at the time:  105 tornadoes in 13 states
• 26 killed, 638 injured
• Total damage: $713 million
• Total tornadoes path length: 1227 miles

November may conjure up thoughts of Thanksgiving or of the season's first cold, raw winds.  However, as Dr. Forbes points out in this previously written blog, November is a "second season" for tornadoes in the southern tier of states.

(MORE:  Typical November tornado threat area)

It started the Saturday before Thanksgiving 1992 in Houston. An incredible 7 tornadoes were spawned in just two hours' time in the metro area, with three twisters on the ground at one particular time in Harris County. The strongest tornado, rated F4 destroyed over 200 homes on Houston's east side. Since 1950, this is the strongest tornado to hit the Houston metro.

Another F4 tornado went on a 128-mile long rampage through Mississippi overnight Saturday night into Sunday morning, November 22, claiming 12 lives and damaging or destroying more than 700 homes.

Fifteen total tornadoes touched down in Indiana that Sunday, the largest November outbreak in state records. One tornado was an F4 in southeast Indiana and northern Kentucky. Not to be left out, other F4 tornadoes carved a swath through the far northwest suburbs of Atlanta, and also struck near White Plains and Lake Oconee, Ga.

Finally, a pair of F3 tornadoes in North Carolina killed 2 and injured 59.

From an outbreak near Thanksgiving, we next detail one the week before Easter.

#3:  Palm Sunday Outbreak (April 11-12, 1965)Forbes Impact Index:  46

Fast Facts

• Only 52 tornadoes in 7 states, but 22 were violent tornadoes (F4/F5)
• 260 killed, 3442 injured
• Total damage: $1.19 billion
• Total tornadoes path length: 1043 miles

When it gets warm and humid in the Great Lakes in early April, there is usually a later price to be paid. Unfortunately, that bill comes due via severe weather, and Palm Sunday 1965 was no exception.

This is a clear-cut case that it's not the necessarily the number of total tornadoes that captures the full impact. There were only 52 total tornadoes in this event. Many other outbreaks have had more.

Of all the outbreaks Dr. Forbes examined, however, this Palm Sunday outbreak had the highest percentage of violent (F4/F5) tornadoes. An incredible 22 F4 or F5 tornadoes were documented. The only F5 was the "double tornado" pictured above.

Normalized for inflation, this outbreak is #1 in total damage cost of any outbreak in the study.

The loss of life in this tragic outbreak spurred significant changes within the National Weather Service (NWS). Prior to this event, the system of severe weather watches and warnings we know so well now didn't exist. NOAA Weather Radio didn't exist. Radio and television stations were not involved in the dissemination of warnings and were not connected to the NWS "weather wire".

We've now come to our top 2 worst outbreaks, or "Superoutbreaks".

#2:  April 26-28, 2011 "Superoutbreak"Forbes Impact Index:  70

Fast Facts

• 349 tornadoes in 21 states
• 15 "violent tornadoes", including four rated EF5
• 321 killed, 2775 injured
• Total damage: $11 billion
• Total tornadoes path length: over 3200 miles (Greatest of any outbreak!)

Capping off an awful April for tornadoes, a massive multi-day tornado outbreak swarmed from Texas to the East Coast in late April 2011.  

Hardest hit was the Deep South, particularly Alabama, Mississippi, northwest Georgia, Tennessee. An EF4 tornado ravaged both the Tuscaloosa and west Birmingham metro areas.  The parent supercell spawning the Tuscaloosa/Birmingham tornado tracked 380 miles in just under 7.5 hours from eastern Miss. to western N.C.

(MORE:  One of Worst U.S. Tornadoes...Tuscaloosa)

EF5 tornadoes struck Smithville, Miss., Philadelphia, Miss., Hackleburg, Ala., Phil Campbell, Ala. and Dekalb County, Ala.  April 27, 2011 was the first day on record in the state of Mississippi with a pair of F/EF5 tornadoes on the same day.  

Ground was scoured out in Neshoba County, Miss. by one of the EF5 tornadoes.  Appliances and plumbing fixtures in the most extreme damage swath of the Smithville, Miss. EF5 tornado were "shredded or missing."  The Hackleburg/Phil Campbell EF5 tornado stayed on the ground for 132 miles reaching a peak width of 1.25 miles, sucking up a 25-foot section of pavement and scattering it over one-third mile away in a home!  

(MORE: One of Worst U.S. Tornadoes...Hackleburg, Ala.)

Other hard hit cities included Cullman, Ala., Ringgold, Ga., Cleveland, Tenn., Chilhowie, Va. and Bayse, Va.  

Of the combined fatalities, 240 of those occurred in Alabama alone.  A study by the Centers for Disease Control and the Red Cross found that the violent tornadoes (EF4 or EF5) were responsible for 89.5 percent of the deaths in this outbreak.  The outbreak was Alabama's costliest disaster on record.  

Only one other outbreak ranked worse than the signature outbreak from spring 2011.

#1:  April 3-4, 1974 "Superoutbreak"Forbes Impact Index:  75

Fast Facts

• 148 tornadoes in 13 states and Canada
• 30 "violent tornadoes", including six rated F5
• 307 killed, 5454 injured
• Total damage: $1.5 billion
• Total tornadoes path length: 2521 miles

There are several aspects of this "Superoutbreak" that clearly set it apart:

1) 30 "violent" tornadoes (F4 or F5) in 24 hours! In some years, you may go several years without a single F/EF5 tornado. In the "Superoutbreak", there were six F5 tornadoes in just 24 hours!  Dr. Greg Forbes says the 30-year average number of "violent" tornadoes each year is seven.  So, over four times the yearly average of violent tornadoes occurred in just 24 hours during the "Superoutbreak"!

2) 48 tornadoes were "killers".  This tops the April 2011 "Superoutbreak" (29 killer tornadoes).

3) This occurred prior to Doppler radar networks, the internet, social media, and smartphones able to upload video instantly. Rarely today does a U.S. tornado go "undetected", thanks not only to modern technology, but also improved public awareness, spotter programs, and verification efforts from the National Weather Service. This adds an "inflation" factor to tornado counts over the past couple of decades. This makes the 1974 "Superoutbreak's" tornado count all the more impressive.

Among the hardest hit cities were:

• Xenia, Ohio  (34 killed, $100 million damage from F5 tornado)
• Monticello, Indiana (109 mile path length; longest track of '74 "Superoutbreak")
• Brandenburg, Ky. (28 killed by another F5 tornado)
• Guin, Alabama (F5 tornado moving at forward speed of 75 mph leveled the town)

Incredibly, 16 tornadoes were on the ground at one time in the state of Indiana alone on April 3, 1974.

Incidentally, TWC Severe Weather Expert Dr. Greg Forbes (Find him on Facebook) has a close connection with the 1974 Superoutbreak.  Dr. Forbes personally surveyed the damage and wrote his Ph.D. largely on the 1974 "Superoutbreak", while studying under pioneering tornado expert, Dr. T. Theodore Fujita. Yes, that Fujita...as in the Enhanced-Fujita scale.