2011 is shaping up to be a year that contradicts historical patterns.
Since 1950, when ISO's Property Claim Services (PCS) began to keep records on catastrophes, 88 hurricanes have met the organization’s definition of a catastrophe, and those storms have cost insurers more than $136.5 billion. During the same period — 1950 to 2010 — 1,251 severe weather events meeting the definition have cost insurers $118.5 billion. The comparison shows that damage from a single severe weather event is typically not very costly.
In fact, over the years, hurricanes have produced 42 percent of all and severe weather events just 36 percent.
That pattern may change in 2011.
It’s obviously too early to tally hurricane losses for this year, but we’ve already witnessed startling devastation from severe weather events, particularly tornadoes, that have plagued the United States since the end of February. From late February through March, PCS identified five severe weather events as catastrophes. They cost insurers an estimated $815 million. But that’s a small fraction of the devastation caused by storms in April and May.
The National Weather Service (NWS) has received preliminary reports of 875 tornadoes during April alone. The number may change as the NWS conducts its investigations, but as it stands, it is nearly 500 percent greater than the average for the month over the previous three years.
Following is a summary of tornado activity identified in each year since 2008. Keep in mind that the numbers for 2011 are only preliminary and are subject to change. (The preliminary count for 2011 is based on eyewitness reports and not a count of actual tornadoes.)
The severe weather outbreaks in April and May have caused insured property damage currently estimated at $15.03 billion. Most notable were the tremendous losses in several urban areas, including Birmingham and Tuscaloosa, Alabama; Joplin, Missouri; and Springfield, Massachusetts. It’s been a long time since we’ve seen so much destruction across densely populated areas. When several major tornadoes hit such areas, the extent of insured damage is equal to that of a significant hurricane.
The catastrophe damage incurred so far in 2011 is much greater than we’ve seen in many years. But the situation could become much worse if the hurricane season is as active as predicted, and one or more cyclones make landfall.
 Dollar values reported here are “nominal” values, or the total cost of the events at the time of the catastrophe. These values have not been updated for inflation or demographic changes.