Lloyd’s: US tornado season gets underway
Householders, businesses and farmers up and down the US are battening down the hatches in preparation for the 2010 tornado season, which gets properly underway this month.
In a new report, Lloyd’s of London is taking a look at tornados in the US. The peak of US tornado season varies by geographic region but usually begins in the southern states during April moving through the southern plains in May and June. The peak time for twisters in the Midwest and northern plains typically comes during June and July.
The Lloyd’s report says there were over 1,150 tornadoes in 2009, according to the National Oceanic and Atmospheric Administration’s National Climatic Data Center. The highest concentration of tornado reports were clustered in the southeast and into the Midwest. The largest outbreak last year occurred on April 10 with 73 tornado reports across the southeastern US, killing two people.
Together tornadoes and related thunderstorms caused insured damages totaling nearly $10 billion last year.
According to Lloyd’s, the largest tornado outbreak on record occurred at the beginning of April 1974 when there were 148 tornadoes confirmed in 13 US states in a single 24 hour period. The outbreak swept an area of 900 square miles along a path length of 2,600 miles from Alabama to Ontario. Over 300 people were killed and 5,484 were injured.
The costliest single outbreak, now referred to by weather watchers as Super Tuesday, started on February 5, 2008 and culminated in 82 twisters touching down in 10 states leaving insurers with a bill of nearly $1billion. Fifty-seven people were killed.
The US Midwest is especially prone to tornadoes and thunderstorms as a result of the contrasting air masses found in that area. Cold air from the Rockies meets with warm and moist air from the Gulf of Mexico, creating instability and an increase in activity.
With wind speeds that can reach nearly 300mph, tornadoes can be deadly and cause severe property damage, according to Donald Griffin, vice president personal lines at the Property Casualty Insurers Association of America.
“Because tornadoes can occur rapidly and with little warning, advanced preparation is very important. We encourage consumers to know the warning signals used in their community and be prepared to take cover when alerted,” he advises.
For many people living in so called Tornado Alley, preparing for the tornado season is like going onto a war footing.
The PCI advises maintaining an emergency storm kit with a radio, flashlight, batteries and first-aid items. Other suggested steps include conducting regular tornado drills with your family.
But not everyone is afraid of tornadoes and storm chasing tours of tornado alley in the peak season are a big draw for a growing number of people in the US. This year, ten day tours that cost around $3,000 per person are selling out fast.
Unfortunately, says the Lloyd’s report, there are no methodologies that have proven useful in the prediction of tornado seasons, according to Steve Drews, associate director and lead meteorologist at Impact Forecasting LLC, an Aon Benfield company.
“There is a very, very loose correlation with the El Niño/Southern Oscillation and tornado frequency, but this correlation is very weak at best.”
The good news is that tornadoes do not appear to be getting more severe or frequent, Drews adds. Nevertheless some forecasters in the US believe this year’s tornado season will shift eastward into the Midwest and become more active in late April through June. They expect tornado activity to pick up after a relatively quiet start as the El Niño effect begins to weaken and the Gulf of Mexico sea surface temperatures warm.
