April and May U.S. severe weather estimated to cost insurers $15 billion

Aon Benfield have issued a report analysing the severe thunderstorms and tornadoes which swept across the U.S. midwest, southeast and plains during April and May causing widespread damage and destruction. They identify at least eight separate outbreaks with five of them causing at least $1 billion in losses. Their estimate of insured losses of $15 billion is nearly three times the 1990-2010 annual average for severe weather losses in the U.S.

The fact that a two month period has resulted in close to three times the annual average of severe weather losses really shows how unusual and severe the convective weather has been this year. Of the eight periods that Aon Benfield identifies in the report, two were particularly severe, 22nd – 28th April and 21st – 27th May.

The period at the end of April saw the largest outbreak of tornadoes in history with 334 separate tornado touchdowns causing devastation across the southeast and the Tennessee Valley. It was this spell of weather which spawned the Tuscaloosa tornado. Aon Benfield estimate that the period at the end of April caused $5 billion in insured losses (slightly less than the risk modellers estimates).

The period at the end of May was responsible for the tornado that destroyed much of the town of Joplin, Missouri, causing 154 fatalities and massive losses for a single storm (EQECAT put the Joplin losses alone at $3 billion). Aon Benfield put an insured loss estimate of $4.5 billion on the 6 day period at the end of May.

Steve Jakubowski, President of Impact Forecasting, said: “”The late-May stretch was highlighted by an outbreak that spawned a massive EF-5 tornado that destroyed a large section of Joplin, Missouri. The tornado led to 154 fatalities in the city, becoming the deadliest singular tornadic event since the National Weather Service officially began keeping records in 1950. In addition, it is worth noting that the Tuscaloosa and Joplin events will go down as two of the costliest singular tornadoes ever recorded.”

The final toll from this catastrophic two months won’t be known for some time and it is likely to be higher than $15 billion when all claims are in and counted. Of course we are still waiting to hear the final outcome for the exposed Mariah Re catastrophe bond. Add on the devastating flooding affecting parts of the U.S., winter storms earlier this year and the severe hurricane season that is forecast and we could be heading for a record year of U.S. natural catastrophe losses.

You can download the full report from Aon Benfield here.