Risk modelling firm EQECAT have published a summary of the tornado and severe thunderstorm activity in the U.S. for the first half of 2011. You can access the full report, Summary of US Convective Storm Activity for First Half of 2011, from our CatWatch page.
The report discusses the unprecedented levels of convective weather which resulted in severe thunderstorms spawning tornadoes across much of the U.S. midwest and southeast. Outbreaks were particularly severe during April, with more than 300 fatalities and an estimated $4 billion to $7 billion in losses. One particular outbreak from 25th-28th April is likely to become the most expensive tornado event in history says EQECAT and contributes to an overall insured loss for the first half of the year of between $12 billion and $18 billion.
Interestingly EQECAT say that they cannot find any correlation between climate change and the severe tornadic activity of 2011. They say that a review of tornado data doesn’t identify an ongoing trend of increasing tornadoes associated with temperature change.
Also of interest is the discussion of potential future trends for tornadoes. EQECAT say that there is no modern trend in increased tornado activity, and actually the trend is for the amount of tornadoes per year to fluctuate considerably. However they do suggest that there is a trend towards increasing losses as the U.S. population has doubled since tornado warnings began being issued and property values have risen greatly, thus increasing both fatality and loss trends. As more rural land is converted to suburban uses the likelihood of tornadoes striking population centres increases so a trend towards greater losses and fatalities is likely to continue.
Access the full CatWatch report on the convective storm activity during 2011 here.