2011: Year of the Tornado

[phantom power]

The year 2011 will forever be known as Year of the Tornado in the U.S. A series of violent severe storms swept across the Plains and Southeast U.S., bringing an astonishing six billion-dollar disasters in a three-month period. The epic tornado onslaught killed 552 people and caused $25 billion in damage. Three of the five largest tornado outbreaks on record hit in a six-week period, including the largest and most expensive tornado outbreak in U.S. history--the $10.2 billion dollar Southeast U.S. Super Outbreak, April 25 - 28. Even more stunning was the $9 billion late-May tornado outbreak that brought an EF-5 tornado to Joplin, Missouri. The Joplin tornado did $3 billion in damage and killed 158 people--the largest death toll from a U.S. tornado since 1947, seventh deadliest tornado in U.S. history, and the most expensive tornado in world history. In a year of amazing weather extremes, this year's tornado season ranks as the top U.S. weather story of 2011.


Figure 4. Death rate per million people per year in U.S., 1875-2011. Thin line with dots is raw rate, curved thick line is death rate, filtered by 3-point median and 5-point running mean filter, and straight solid lines are least squares fit to filtered death rate for 1875-1925 and 1925-2011. Dashed lines are estimates of 10th and 90th percentile death rates from 1925-2000. The death rate fell from 8 per million to .12 per million between 1940 and 2010. Image credit: A Brief History of Deaths from Tornadoes in the United States, Harold Brooks and Charles Doswell III, and updated by Harold Brooks in 2011.


Figure 5. Number of EF-1, EF-2, EF-3, EF-4 and EF-5 tornadoes from 1950 to 2011. The total shown for 2011 is preliminary and uses unofficial numbers through November 17, but 2011 now ranks in 2nd place behind 1973. There is not a decades-long increasing trend in the numbers of tornadoes stronger than EF-0, implying that climate change, as yet, is not having a noticeable impact on U.S. tornadoes. However, statistics of tornado frequency and intensity are highly uncertain. Major changes in the rating process occurred in the mid-1970s (when all tornadoes occurring prior to about 1975 were retrospectively rated), and again in 2001, when scientists began rating tornadoes lower because of engineering concerns and unintended consequences of National Weather Service policy changes. Also, beginning in 2007, NOAA switched from the F-scale to the EF-scale for rating tornado damage, causing additional problems with attempting to assess if tornadoes are changing over time. Data provided by Harold Brooks, NOAA/National Severe Storms Laboratory.

http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=2007

[AlecBGreen]

1. satellite imagery from NOAA

covers the month of april and shows all recorded tornados. Highly reccomended even for non-science nerds.

http://www.nnvl.noaa.gov/MediaDetail.php?MediaID=731&MediaTypeID=2