It’s been seven years since a large hurricane – Hurricane Ike – threatened the Gulf states, and increasingly there’s talk among scientists that the Atlantic Ocean may be moving toward a more “quiet” period.
Hurricanes tend to come in bunches, and since about 1995 the Atlantic Ocean has burned hot with storms, spawning monster years in the 2000s when hurricanes like Katrina, Rita and Wilma pounded Florida, Louisiana and Texas.
Before then, in the 1970s, 1980s and early 1990s, the Atlantic was comparatively quiet, with fewer named storms each season.
Now, after a 20-year, frenetic period, the cycle may be swinging back down. For the first time in a long time, sea surface temperatures in the Atlantic where hurricanes commonly form are cooler than normal. Seasonal forecasters predict fewer than 10 named storms this year, far below the 15 or more storms that have formed in most years since 1995.
[Chris Landsea, a senior scientist at the National Hurricane Center] says we need a few more hurricane seasons to know whether we really have entered a quiet period. Phil Klotzbach, a Colorado State University scientist known for publishing seasonal forecasts for hurricanes, is a little more confident.
The hurricane cycle is known as the Atlantic Multidecadal Oscillation, or AMO, and it reflects changes in sea surface temperatures from the equator to the Arctic Circle in the North Atlantic Ocean. Periods of increased hurricane activity correlate to warmer sea temperatures, and slower periods correspond to cooler temperatures.
Klotzbach tracks the AMO closely, and it has essentially been negative – cooler than normal – since 2012.
“I would say at this point that my confidence that the AMO has flipped to negative has grown somewhat,” he said. “If this hurricane season ends up being as quiet as we are predicting, that would make three below-average seasons in a row. The odds of three below-average seasons in a row in a positive AMO would be quite unlikely.”
You can see the NHC’s 2015 forecast here. As the story and the NHC scientists take pains to remind us, it only takes one storm to make a given season a catastrophe. Hurricane Alicia in 1983 hit during a similarly “quiet” period. So remember the lessons that have been drilled into us all over the years – have bottled water at hand, know your evacuation route or be prepared to shelter in place, and stay on top of the news. And if you live in Katy, run for your lives.