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With all of the severe weather lately, and the associated tragedies throughout the heartland of America, I thought that it might be useful to gain some perspective on how tornadoes effect this country. This increase in weather severity may plausibly have something to do with anthropogenic global warming (AGW), but for now, limited perspective will suffice.

It is important to note that just because there is severe weather, does not mean it is because of AGW. Severe weather one year is just bad weather one year. To be caused by AGW, or to be indicative of AGW, the overall trend of the weather must tend towards a greater severity, over a very long period of time.

1. How many tornadoes hit the U.S. yearly?
Tornado reporting methods have changed a lot in the last several decades, so the officially recorded tornadoes are believed to be incomplete. Although the actual average is unknown, recent trends indicate the number is around 1,300. This year, the number of tornadoes is 1,151 reports which is on pace for a record season.

2. How many people are killed by tornadoes every year?
On average, about 60 people are killed by tornadoes every year, most from flying or falling debris.

3. What were the top 10 deadliest U.S. tornadoes in the past?

  1. March 18, 1925, Tri-State (Mo./Ill./Ind.), 695 deaths
  2. May 6, 1840, Natches, Miss., 317 deaths
  3. May 27, 1896, St. Louis, Mo., 255 deaths
  4. April 5, 1936, Tupelo, Miss., 216 deaths
  5. April 6, 1936, Gainesville, Ga., 203 deaths
  6. April 9, 1947, Woodward, Okla., 181 deaths
  7. April 24, 1908, Amite, La.,/Purvis, Miss., 143 deaths
  8. May 22, 2011, Joplin, Mo., 124 deaths (pending final totals)
  9. June 12, 1899, New Richmond, Wis., 117 deaths
  10. June 8, 1953, Flint, Mich., 115 deaths

4. What city has been hit by the most tornadoes?
Oklahoma City. The exact count is not known, but the total is more than 100.

5. Which city/town holds the most tornado fatalities in a single city or town?
Murphysboro, Ill. – at least 234 people lost their lives during the March 1925 “Tri-state” tornado.

6. What was the deadliest U.S. tornado day?
The Dixie Alley tornado outbreak on April 27, 2011, set a record of 335 deaths.

7. What was the biggest outbreaks of tornadoes?
The Super Outbreak of April 3-4, 1974, spawned 148 confirmed tornadoes in 13 states and resulted in the second highest death toll (317) for a tornado outbreak in the United States.

The April 25-28, 2011, outbreak may exceed this number once the final number of tornadoes is counted. So far, there have been 492 tornado reports.

8. What was the biggest known tornado?
The Hallam, Neb., tornado of May 22, 2004, had the peak width of nearly 2.5 miles, which is close to the maximum size for tornadoes.

9. What was the strongest tornado? What is the highest wind speed in a tornado?
Tornado wind speeds have only been recorded in weaker ones, since violent tornadoes could destroy weather instruments. The highest winds that have ever been found during a tornado were about 302 mph near Bridge Creek, Okla., on May 3, 1999.

10. What were the costliest tornadoes?
On June 8, 1966, the Topeka, Kan., tornado had a cost of about $1,680,136,978 in 2010 dollars.

Source: USGS