NewsNovember 30, 2012

Hurricane Season Ends; Sandy Will Long be Remembered

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Andrew Freedman

By Andrew Freedman

The 2012 Atlantic Hurricane season officially came to a close on Friday, after four land-falling storms left coastal communities in tatters from Louisiana to New York. For the third straight season there were 19 named storms in the Atlantic, which is the third-highest level of storm activity observed since 1851. Ten of those storms went on to become hurricanes, only one of which, Hurricane Isaac, made landfall. But 2012 will long be remembered as the season of Hurricane Sandy. While it was officially classified as a post-tropical cyclone when it plowed into the New Jersey coastline on Oct. 28, it was by far the deadliest and most damaging storm of the season.

Chart showing the path and strength of the 2012 Atlantic tropical storms and hurricanes.
Click to enlarge the image. Credit: NWS/NHC.

Since 1851, only two hurricane seasons — 2005 and 1933 — have been busier than 2010, 2011, and 2012. The Atlantic has been in a period of active hurricane activity since 1995, which is thought to be related to a naturally varying climate cycle involving warmer Atlantic sea surface temperatures, among other factors. According to NOAA, such periods of high activity typically last between 25 to 40 years.

Manmade global warming may also be having some small effects on tropical storms and hurricanes, but due to changes in hurricane observations since the 19th century, detecting such changes is extremely difficult. By using satellites and aircraft reconnaissance, scientists are now much more capable of spotting the short-lived, weaker storms that used to be missed by observation systems that were dependent on ship and coastal weather reports, for example. Computer modeling studies have shown that hurricanes in the North Atlantic Basin may become stronger as the oceans and atmosphere continue warming, but that there may be fewer such storms.

Despite the unusually high number of storms in recent years, the U.S. has now gone a record seven years since the last major hurricane of Category 3 intensity or above on the Saffir-Simpson Scale made landfall. The last major hurricane to strike the U.S. was Hurricane Wilma, which struck Florida on Oct. 24, 2005.

For the millions on the East Coast impacted by Sandy, though, its technical classification provided no relief. Because of its enormous size — its breadth of tropical storm force winds were the largest of any Atlantic hurricane on record, at about 900 miles across — Hurricane Sandy brought a storm surge that was more characteristic of a major hurricane when it plowed into the Northeast. Sandy’s price tag — currently approaching $100 billion and rising — is going to rival Hurricane Katrina’s, a 2005 storm that struck the Gulf Coast at Category 3 intensity.

Hurricane Sandy killed at least 125 people in the U.S. Hurricane Isaac also brought a damaging storm surge to coastal Louisiana when it made landfall in late August. Both storms are spurring NOAA to rethink its issuance of hurricane watches and warnings, and consider adding a separate storm surge warning to the agency’s products. Currently, the Saffir-Simpson categories do not consider storm surge.

“This year proved that it’s wrong to think that only major hurricanes can ruin lives and impact local economies,” said Laura Furgione, acting director of the National Weather Service, in a press release. “Mother Nature reminded us again this year of how important it is to be prepared and vigilant.”

Image of Hurricane Sandy approaching the U.S. coastline on Oct. 29, 2012. This was taken from the NOAA/NASA Suomi NPP satellite.
Click to enlarge the image. Credit: NOAA.

An average Atlantic Hurricane season has 12 named storms, six hurricanes, and three major hurricanes. This season was busier than the National Oceanic and Atmospheric Administration (NOAA) had predicted, largely because an El Niño event in the Pacific, which would have held storm activity down in the Atlantic, never fully materialized. Although it was an above-average season, there was only one major hurricane in the Atlantic, Hurricane Michael, and that storm remained over the open ocean.

“Never in known history has the U.S. been so fortunate in avoiding the devastation brought on by category 3-5 hurricane landfalls,” wrote hurricane expert Brian McNoldy on the Capital Weather Gang blog. “One doesn’t need to be a fortune teller to predict that such a streak will end eventually, and hopefully this long vacation that we’ve enjoyed hasn’t made us complacent.”

One other noteworthy aspect of the 2012 season is that there were several early-season storms. Two tropical storms, Alberto and Beryl, formed in May, before the June 1 kickoff of the official season. Beryl, which made landfall near Jacksonville, Fla., was the strongest pre-season storm to strike the U.S. in recorded history, according to McNoldy.

And while Friday marked the “close” of the season, it does not mean hurricanes can't or won't form after this date. Since 1851, 20 named storms have formed or persisted into in the month of December, and four of them have occurred just in the past decade, most recently in 2005.

Related Content:
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Hurricane Isaac Spurs Rethink of Storm Surge Warnings
Will Our Luck Run Out? Major Hurricane Gap in U.S.
New Study Ties Hurricane Strength to Global Warming