Hurricane Sandy: A 1-in-700 Year Event

Hurricane Sandy was one of the worst storms to hit the east coast in our lifetime. The odds of actually experience a super storm like this was a 1-in-700 year event. The storm’s near-perpendicular strike on the coast was a major factor in the severe flooding seen in New York, New Jersey and other nearby states. The rareness of the storm’s track doesn’t mean that the coast is safe from other severe storms in the future.

“The particular shape of Sandy’s trajectory is very peculiar, and that’s very rare, on the order of once every 700 years,” said Timothy Hall, a senior scientist at the NASA Goddard Institute for Space Studies who co-authored the study. That means that in any particular year, the chance of such a storm track happening is 0.0014 percent.

Hurricane Sandy caused about 150 deaths, along with billions of dollars in damage when it hit the Caribbean and the U.S. East Coast in late October 2012. The storm’s power came from a combination of factors found in a study done in May 2013, including its large size while out at sea and a full moon that made tides 20 percent higher than normal, both of which ramped up Sandy’s storm surge. Study researchers also pointed to weather patterns that affected Sandy’s track. A region of high pressure blocked Sandy from taking a more common track out over the western North Atlantic, forcing the storm into the coast. Sandy also interacted with a mid-level, low-pressure system in the atmosphere, which helped push the storm along its unusual track.

The researchers could not rely on previously recorded data, as Sandy’s trajectory and near-direct impact on New Jersey was unprecedented in the historical record. Most of the tracked landfalls in the model grazed the coast before veering out into the Atlantic. Sandy, by contrast, hit the coast at an angle of just 17 degrees from perpendicular, almost perfectly crisscrossing the typical storm track.

A February study in the journal Nature Climate Change predicted that, by the end of the century, a typical “500-year” storm surge in New York would actually happen anywhere between once every 50 years to once every 240 years. The effect of surges, though, is very likely to increase in the next 100 years, mostly due to higher sea levels. Warming oceans and melting glaciers will raise sea levels, worsening storm surges in the future, Hall said. In addition, warmer air holds more water vapor, resulting in more rainfall from strong storms, which could exacerbate flooding, another common issue with tropical storms.

Hurricane Sandy, the super storm that devastated so many families along the east coast was said to be a 1-in-700 year event. Unfortunately due to recent studies, that gap between the years is closing rapidly.