Tornado Patterns In 2011 Not an Anomaly

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Only three of the top 10 states with the most tornados from 1980 to 2009 currently are in the so-called Tornado Alley, according to a new CoreLogic tornado and hail risk report. The change, however, is not an anomaly, as everyone believed.

CoreLogic reports that “historical data” challenge the long-held notion of risk concentration in Tornado Alley that typically it includes the Great Plains states along with surrounding Texas, Oklahoma, Kansas, Nebraska, Colorado, North Dakota, South Dakota and Illinois.

In 2011 the trail of destruction occurred outside of the Midwest hitting much of Arkansas, Mississippi, Alabama and even Virginia, which were seen as an anomaly.

The unexpected destruction brought about by these storms forced many insurance companies to rethink the way they assess natural hazard risk, said Howard Botts, vice president and director of database development for CoreLogic Spatial Solutions, suggesting the mortgage industry needs to change its risk management policies and procedures accordingly.

Historical data show “the frequency and severity of storms is much more widespread than commonly believed,” indicating the apparent shift in geographic distribution of tornado related losses in 2011 does not represent a drastic change in storm patterns and asks for further comparative data analysis that can help prepare for future hazardous weather losses.

Entitled "Tornado and Hail Risk Beyond Tornado Alley" the report analyzed the impact of record-breaking hazard events over 2011 for insurance companies and homeowners. It finds that tornado and hail weather patterns have changed moving mostly outside of the country’s narrow Midwest corridor or Tornado Alley.

It found that “the perceived dramatic increase in the frequency and severity” of storms in recent years could be attributed to factors that include improved observational tools, broadened geographic distribution of modern Doppler radar stations, population growth and migration to suburban areas.

Furthermore, these insiders expect the analyses of claims losses associated with severe weather events in 2011 will likely cause many insurers and enterprise risk managers to approach state Department of Insurance Commissioners with rate change requests in 2012.

While nonstop 24/7 disaster news reporting on television and online have increased public awareness in recent years, the report notes “growing scientific evidence” shows there has been an actual increase in the number of severe weather outbreaks due to global warming.

Tornado risk extends across most of the Eastern half of the U.S. rather than being confined to the Midwest. CoreLogic reviewed National Oceanic and Atmospheric Association data, which not only indicates that of the top 10 states with the highest number of tornado touchdowns between 1980 and 2009 only three actually fell within Tornado Alley—but also, at least 26 states have some area facing extreme tornado risk.

In the last decade—from 2000 to 2011—estimated property damages within Tornado Alley states were approximately $2.5 billion. Meanwhile, the 16 states located outside of Tornado Alley that endured nearly $15.5 billion in property damages, ranged from Illinois and Ohio, to Mississippi and Alabama, and also extending North to parts of Minnesota and as far south as Florida.

Hail risk also is significant. In the Tornado Alley region hail storms caused approximately $4.3 billion in property damage and nearly $1 billion in crop damage between 2000-2011. At least 11 states have significant areas facing extreme hail risk extending outward from the central Great Plains to include states as far east as Georgia and the Carolinas. Plus, almost every state east of the Rocky Mountains has some area facing a moderate or higher level of hail risk.

The 16 states with the next highest amounts of hail damage outside of Tornado Alley reported about $3.2 billion in property damage and $400 million in crop damage over the same time period.

To map and analyze the situation in various states CoreLogic is using its recently launched proprietary property-level risk assessment tools Wind Probability and Hail Probability that assess risk based on geographical areas of 10 x 10 kilometers, or 6.2 x 6.2 miles, that are smaller than the average risk models used in the past.

The report includes charts, images and risk maps for the top 16 states outside of the traditional Tornado Alley corridor with the greatest exposure to tornado and hail disasters.