Greensburg KS High School Tornado Damage May 2007

In mid-May, Kansas, Oklahoma and Texas are at the midpoint of the peak tornado season (April-June) on the south plains — though, of course, tornadoes may occur at any time of year.

As with all hazardous weather phenomena, in recent decades the death toll from tornadoes, though erratically variable, has generally declined, while the extent of property damage has greatly increased.

As we observed in Risk of Death: Natural Hazard Mortality Map, tornadoes are responsible for 11.6% of all deaths due to natural hazards in the United States, trailing heat or drought (19.6%), severe weather (18.8%), winter weather (18.1%), and floods (14%), just above lightning (11.3%), and far above hurricanes and tropical storms (2%).

But as last year’s Congressional Research Service report on Severe Thunderstorms and Tornadoes in the United States points out, tornadoes remain “the most destructive products of severe thunderstorms, and second only to flash flooding as the cause
for most thunderstorm-related fatalities. Damages from violent tornadoes seem to be increasing, similar to the trend for other natural hazards, and some analysts indicate that losses of $1 billion or more from single tornado events are becoming more frequent. Insurance industry analysts state that tornadoes, severe thunderstorms, and related weather events have caused nearly 57%, on average, of all insured losses in the United States in any given year since 1953.”

This increase in damage does not imply that there is any increase in the number or intensity of tornadoes, however. As that same report notes, “part of the difficulty in sorting out trends in frequency and intensity of severe thunderstorms and tornadoes lies in the way they have been observed and reported. For example, the number of annual reported tornado occurrences has doubled between 1954 and 2003. Some studies indicate that the doubling reflects changes in observing and reporting. When the artificial trend produced by these changes is removed, the adjusted data show little or no trend in the number of reported tornadoes since the 1950s.” [emphasis added]

One very frequent misperception of tornadoes is the prevalent view that Kansas is uniquely prone to their destructive force. Kansas has indeed endured a number of destructive twisters, and doubtless will continue to do so. According to the National Oceanic and Atmospheric Administration, Kansas experienced an average of 36 reported tornadoes each year during the thirty year period from 1961 to 1991 – a number which left Kansas tied with Nebraska for fourth place, behind Texas (137), Florida (52) and Oklahoma (47), and just barely ahead of Iowa (35).

But Texas is a very big state, so perhaps it’s more reasonable to consider the prevalence of tornadoes per 10,000 square miles. By this measure, again according to NOAA, and for the years 1961-1991, Kansas trails Florida (9.59), Oklahoma (6.85), Indiana (6.41), Iowa (6.25), Louisiana (6.07), Mississippi (5.51), Texas (5.23), Delaware (5.18), Illinois (4.86), and Nebraska (4.70) at an average of 4.65 tornadoes per 10,000 square miles per year.

In terms of average fatalities, the story is much the same, with Kansas, at an average of 2 fatalities per year, trailing Texas, Mississippi, Alabama, Arkansas, Oklahoma, Illinois, Indiana, Ohio, Michigan and Tennessee.

Here’s what storm chaser Joshua Wurman says about tornado fatalities on the NOAA/National Science Foundation site Vortex2: “The deadliest tornado in history was invisible. In 1925, the Tri-State Tornado ravaged a mile-wide path for 219 miles across Missouri, Illinois, and Indiana at 60 miles per hour—twice the forward speed of the average tornado. It lacked the classic funnel cloud, but the damage was catastrophic: nearly 2,000 people were injured, property losses totaled more than $16 million, and 689 people died.

“The high death count in the Tri-State disaster is extremely unusual. The odds a person will be killed by a tornado in a year are 1 in 4,513,000. Over that same period, it is more likely a person will die from a fall off a cliff—1 in 4,101,000—or will be diagnosed with leprosy—1 in 2,930,000.”

None of this is intended to deny the terrible destructive power of tornadoes. Certainly, the citizens of Haysville are intimately familiar with their deadly ways. Just last year, we comemmorated the tenth anniversary of a tornado which ripped through the heart of our city. (For an extensive review of the damage wrought to Haysville by the tornado which struck on the evening of May 3, 1999, see our anniversary posts here, here and here. For scenes of more recent devastation wrought by tornadoes elsewhere, see the Federal Emergency Management Agency Photo Library.)

Indeed, the Haysville Community Library now stands squarely in the path of devastation cut by that tornado — a resounding affirmation of our citizens’ faith in their ability to transcend nature’s most destructive storms

Next Up: Tornado Survival; Tornado Formation

Tornado, Wichita-Andover 1991 (Chris Fiebig)

Tornado, Wichita-Andover 1991 (Keith Lathrum)

Tornado, Haysville 1991 (William Goodwin)

Published in: on May 16, 2010 at 1:48 pm  Leave a Comment  

The URI to TrackBack this entry is:

RSS feed for comments on this post.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s

%d bloggers like this: