May 21–26, 2011 tornado outbreak sequence

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May 21–26, 2011 tornado outbreak
EF4 tornado that struck Chickasha, Oklahoma.
Date of tornado outbreak: May 21 – May 26, 2011
Duration1: Six days
Maximum rated tornado2: EF5 tornado
Tornadoes caused: 242 confirmed
Highest winds:
Largest hail:
Damages: ~$7 billion (2011 USD)[1]
Fatalities: 178 (+ 6 non-tornadic)[2][3]
Areas affected: Midwest, isolated tornadoes elsewhere

1Time from first tornado to last tornado
2Most severe tornado damage; see Enhanced Fujita Scale

The May 21–26, 2011 tornado outbreak was a deadly tornado outbreak across the Midwestern and Southern regions of the United States. Most of the tornadoes developed in a corridor from Lake Superior southwest to central Texas; isolated tornadoes occurred in other areas. An especially powerful tornado destroyed one-third of Joplin, Missouri, resulting in 158 deaths and 1000 injuries.[4][5] The Joplin tornado is the deadliest in the US since April 9, 1947, when an intense tornado killed 181 in the Woodward, Oklahoma area. Tornado-related deaths also occurred in Arkansas, Kansas, Minnesota, and Oklahoma. Overall, the tornado outbreak resulted in 184 deaths, 6 of those non-tornadic, making it second only to the April 25–28, 2011 tornado outbreak as the deadliest since 1974, and the second costliest tornado outbreak in US history behind that same April 2011 outbreak, with insured damage estimated at $4–7 billion.[1]

Meteorological synopsis[edit]

April 2011 was the most active month for tornadoes on record, capped by a very large tornado outbreak (the largest on record) that killed more than 324 people in the final week. In contrast, the first three weeks of May were remarkably quiet; only a few isolated tornadoes were confirmed. However, that pattern changed abruptly as a strong low pressure area and associated dry line and cold front tracked eastward.

On May 21, a small system of thunderstorms developed in Brown County, Kansas while another system formed to the southeast of Emporia, Kansas. The Brown county system spawned a brief tornado over Topeka, Kansas, causing minor damage. This system also caused significant damage in Oskaloosa, Kansas, and other communities. Meanwhile, the Emporia system spawned an EF3 tornado in Reading, Kansas; one person was killed, several others were injured, and at least 20 houses were destroyed.[6] These two systems developed several other tornadoes throughout the evening.[7]

EF3 tornado that struck Reading, Kansas
Outbreak death toll
State/Province Total County County
Arkansas 5 Franklin 3
Johnson 2
Kansas 3 Lyon 1
Stafford 2
Minnesota 1 Hennepin 1
Missouri 158 Jasper 158
Oklahoma 11 Canadian 7
Grady 1
Logan 2
Major 1
Totals 178
Only tornado-related deaths are included

A moderate risk of severe weather was issued for much of the Midwest, as well as further south to Oklahoma for May 22. The first tornadic supercell developed in the mid-afternoon hours over the western Twin Cities in Minnesota, and caused moderate damage in the Minneapolis area.[8] Shortly thereafter, an intense tornado crept towards Harmony, Minnesota, prompting the National Weather Service to issue the first tornado emergency of the outbreak. Late that afternoon, a large and extremely intense multiple-vortex tornado left catastrophic destruction in Joplin, Missouri; it was the deadliest single tornado in the U.S. since at least 1947.

Once again, a moderate risk of severe weather was issued on May 23—this time for the southern Plains and the lower Great Lakes. Forecasts showed that the main threats would be damaging wind and large hail instead of frequent tornadoes; the stationary front lacked the necessary wind shear to sustain the type of tornadic supercells seen on May 22. This prediction came to light, as only scattered, and mostly weak tornadoes were reported throughout the day. However, an EF2 tornado caused significant damage in Tennessee.

On May 24, a high risk of severe weather was issued for parts of south-central Kansas, central and eastern Oklahoma, and extreme north-central Texas; a moderate risk was issued for surrounding areas in those three states plus northwestern Arkansas and southwestern Missouri. Throughout this region, strong to violent tornadoes were considered to be highly probable for three reasons: (1) the stationary front was expected to maintain its position over the region, (2) wind shear was expected to greatly increase, and (3) these elements would be associated with an incoming trough. Late that morning, the tornado threat increased to 45%, a rare occurrence matching the widespread April 27 outbreak.[9] At 12:50 p.m. CDT, the SPC issued a PDS tornado watch for parts of central Oklahoma, including Oklahoma City, and northern Texas, in effect until 10:00 p.m. CDT.[SPC 1] Numerous tornadoes touched down in several regions, with the first activity being in western Oklahoma that afternoon where several very intense tornadoes developed, including another EF5 (the sixth of the year). They did not cause extensive damage in Oklahoma City, but 10 deaths were reported among extensive damage just to the western and southern suburbs of the OKC metro area. Other tornado clusters developed in central Kansas that afternoon and in the Dallas-Fort Worth Metroplex that evening.

Once again on May 25, a high risk of severe storms was issued for the middle Mississippi River valley from near Memphis, Tennessee northward to north of Evansville, Indiana, and was expanded late that morning northward to near Indianapolis, Indiana, northwest to near St. Louis, Missouri, southeast to just west of Nashville, Tennessee and southwest to near Little Rock, Arkansas.[10] Several hours before the outbreak was set to begin, a PDS tornado watch was issued for western Kentucky, southern Indiana, the southern half of Illinois and eastern Missouri. The entire state of Indiana, southern Michigan, and most of Missouri were under tornado watches. Widepread tornado activity occurred that day across the central and eastern US. An EF3 destroyed many homes in the town of Bedford, Indiana, and an EF2 wedge tornado caused severe damage in Sedalia, Missouri.

Tornado activity continued on May 26, but most were weak. 8 separate EF1 tornadoes touched down across Pennsylvania. An isolated EF3 tornado destroyed multiple homes near Bush, Louisiana.

Notable tornadoes[edit]

242 108 90 31 8 3 2

Joplin, Missouri[edit]

Damage to St. John's hospital

On May 22, a large, devastating tornado tracked across Joplin, Missouri leaving behind catastrophic damage. It was a multiple-vortex tornado in excess of 1 mile (1.6 km) wide. Mainly the southern part of the city was affected with most structures in the area either damaged or destroyed. 158 people[11][12][13] were killed on the 22.1 miles (35.6 km) path through Jasper and Newton counties in Missouri, making it the deadliest U.S. tornado since 1947, and one of the deadliest single tornadoes ever recorded. Among the most heavily damaged structures was St. John's Hospital (pictured right). It will have to be destroyed and rebuilt. Damages were estimated at around $2.8 billion (2011 USD).

El Reno–Piedmont, Oklahoma[edit]

A de-barked tree just north of El Reno with various debris, including a car, piled at its base. Note the severe ground scouring in the foreground.

On May 24, a long-tracked, violent tornado touched down south of Calumet, Oklahoma. It produced complete destruction near El Reno and Piedmont, before striking the northwest side of Guthrie, causing more significant damage there before dissipating. The tornado caused severe devastation along most of its path, including the destruction of numerous vehicles, debarking trees, scouring the earth, and sweeping several well-built homes from their foundations.[14][15]

Many other homes were badly damaged or destroyed along the path. The Cactus-117 oil rig was completely destroyed and gas lines were ruptured, resulting in a fire. The 1.9 million pounds (860,000 kg) oil derrick was blown over and rolled three times.[16][17] Numerous vehicles were thrown and destroyed almost beyond recognition, including a car that was wrapped around a tree. Two vehicles were thrown from I-40 and obliterated, resulting in three fatalities. One vehicle was thrown 780 yards (710 m) into a wooded area had its frame torn from the vehicle body.[18] The frame was mangled and twisted apart, and the vehicle body itself was crumpled around a completely debarked tree.[16] The three victims were found a quarter-mile away, stripped of clothing and left "unrecognizable". Due to an undetected change in direction of the massive, precipitation-obscured tornado, experienced storm chaser Chris Novy was stuck by the outer edges of the tornado, had his windows shattered and some equipment blown out of his vehicle.[19] A 20,000 lb (9,100 kg) oil tanker truck was thrown a full mile (~1.6 km) nearby.[20] Intense ground scouring occurred in this area, as grass was shredded from the ground, leaving nothing but mud behind in some areas.[21] A storage garage was cleanly swept away, and its concrete slab foundation was found badly cracked, and nearly broken into pieces. The tornado finally dissipated after heavily damaging several homes in the Guthrie area.[22][23]

The mesonet station at El Reno recorded a wind gust of 151 mph (243 km/h) as the tornado passed by and which set a record for the highest wind speed observed by the Oklahoma Mesonet.[24] The tornado was rated EF5 on the Enhanced Fujita Scale partially based on University of Oklahoma (OU) mobile Doppler radar measurements, which recorded winds well over 200 mph (320 km/h). Nine people were killed.[25] Research published in 2014 by OU RaXPol researchers reveals winds analyzed as reaching 296 mph (476 km/h), the third highest measurement ever reported, in a subvortex within the parent tornado.[26] This was the first EF5 tornado to strike Oklahoma since 1999, when an F5 tornado killed 36 people in and around southern and central parts of the Oklahoma City metropolitan area. Another violent tornado struck the El Reno area two years later on May 31, 2013 and also struck several storm chasers, three of whom were killed, in addition to a local resident that was following the storm.

Non-tornadic events[edit]

At least three people were killed in the Atlanta metropolitan area as a result of straight-line winds on the evening of May 26, likely due to a downburst.[27]

See also[edit]


  1. ^ a b Noah Buhayar (June 6, 2011). "Joplin Tornado Leads Storms That May Cost Insurers $7 Billion in One Week". Bloomberg. Retrieved June 6, 2011. 
  2. ^ McCune, Greg. "Joplin tornado death toll revised down to 160". Retrieved 12 November 2011. 
  3. ^ Urt Voigt; Alan Scher Zagier (2011-05-23). "Death toll from Missouri tornado rises to 116". Houston Chronicle. Associated Press. Retrieved 2011-05-23. 
  4. ^ "Storm Event Survey". National Weather Service, Springfield, Missouri. June 19, 2012. 
  5. ^ "City official: Joplin tornado death toll at 153". Kansas City Star. June 13, 2011. 
  6. ^ Associated Press (May 21, 2011). "One Killed In Reading, KS Tornado". KAKE. Retrieved May 22, 2011. 
  7. ^ "Storm Reports for May 21, 2011". Storm Prediction Center. National Oceanic and Atmospheric Administration. May 21, 2011. Retrieved May 22, 2011. 
  8. ^ "Storm Reports for May 22, 2011". Storm Prediction Center. National Oceanic and Atmospheric Administration. May 22, 2011. Retrieved May 22, 2011. 
  9. ^ "Storm Prediction Center May 24, 2011 1630 UTC Day 1 Convective Outlook". Storm Prediction Center. National Oceanic and Atmospheric Administration. May 24, 2011. Retrieved May 24, 2011. 
  10. ^ "Storm Prediction Center May 25, 2011 1630 UTC Day 1 Convective Outlook". Storm Prediction Center. National Oceanic and Atmospheric Administration. May 25, 2011. Retrieved May 25, 2011. 
  11. ^ "Storm Event Survey". National Weather Service, Springfield, Missouri. September 15, 2011. 
  12. ^ "Annual U.S. Killer Tornado Statistics". Storm Prediction Center. 
  13. ^ McCune, Greg. "Joplin tornado death toll revised down to 161". Retrieved November 12, 2011. 
  14. ^ Tornado B2 - The Calumet-El Reno-Piedmont-Guthrie Tornado of May 24, 2011
  15. ^ Ortega, Kiel. "Overview of the 24 May 2011 tornado outbreak". 
  16. ^ a b "The Indefinitive List of the Strongest Tornadoes Ever Recorded Part III". 3 October 2012. 
  17. ^ Ortega, Kiel. "Overview of the 24 May 2011 tornado outbreak". 
  18. ^ Ortega, Kiel. "Overview of the 24 May 2011 tornado outbreak". 
  19. ^ Oklahoma tornadoes: Television storm chaser loses vehicle windows
  20. ^ Gardner, Jim (May 24, 2011). Tornado Hits Producing Location-Oklahoma (motion picture). Oklahoma: KFOR. Retrieved January 20, 2014. 
  21. ^ Unknown (May 24, 2011). El Reno Tornado Raw Rescue Video (motion picture). Oklahoma: SurvuM. Retrieved January 20, 2014. 
  22. ^ Ortega, Kiel. "Overview of the 24 May 2011 tornado outbreak". 
  23. ^ Tornado B2 - The Calumet-El Reno-Piedmont-Guthrie Tornado of May 24, 2011
  24. ^ Oklahoma Mesonet Site Records Tornadic Winds
  25. ^ The Calumet-El Reno-Piedmont-Guthrie Tornado of May 24, 2011
  26. ^ Snyder, Jeff; H. B. Bluestein (2014). "Some Considerations for the Use of High-Resolution Mobile Radar Data in Tornado Intensity Determination". Wea. Forecast. doi:10.1175/WAF-D-14-00026.1. 
  27. ^ "Atlanta Severe Storms Claim Three Lives". Bill Deger. AccuWeather. May 27, 2011. Retrieved May 27, 2011. 
  1. ^ "SPC Tornado Watch 356". Retrieved 2011-05-24. 

External links[edit]