Lloyd’s on Tornado Trends

Data on tornadoes can be both unreliable and inconsistent, making it impossible to identify long term trends, according to a new report from Lloyd’s.

Tornado records underreport tornado numbers and changes in classification of tornado strengths adds further uncertainty, making it even more difficult to determine trends in tornado frequency and severity, the report says. Even in the United States detailed records only exist back to 1950.

While the number of officially recorded tornadoes has risen, this can be attributed to better reporting, tracking and more people, homes and infrastructure in the path of a tornado, Lloyd’s says.

The report notes:

Despite the anomalous 2011 season there is no trend in the number of strong to violent tornadoes between 1950 and 2012, evidence that the number of high intensity events has not increased over that period.†

Note: 2011 was an unusually active and deadly year for tornadoes across the U.S., with over 1,600 tornadoes recorded, more than any other year on record except for 2004. Costs were high, with seven individual tornado and severe weather outbreaks recording damages that exceeded $1 billion. Total damage from the outbreaks is estimated at in excess of $28 billion.

But while the number of violent tornado losses may not be increasing, insured losses are.

The report identifies a clear trend of increasing annual aggregate losses to the insurance market and says that billion dollar losses are becoming more common:

As exposure continues to increase, tornadoes represent a more serious threat to the insurance industry. An active tornado season hitting populated areas could result in high damages and it is important that insurers consider modeling and managing potential exposure.†

Check out I.I.I. facts+statistics on tornadoes here. PC360 has more on this story.

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