Atlantic Hurricane

SEPTEMBER-NOVEMBER

>>> Hurricanes and their resulting swells defy all reason. We can try to humanize them by giving them names like Emily and Frances. We can guess their next move with a supercomputer and trajectory models. We can even try to tame them by shooting “hurricane-busting” gel into the clouds. But none of these solutions do us much good. In the end, hurricanes can’t be trained. They act; we react.

While most large low-pressure systems burn slowly and steadily, hurricanes are more like forest fires. In the eastern Atlantic, thunderstorms typically move off the coast of West Africa near Cape Verde and converge with warm ocean vapors and surface winds. These three elements combine to create the out-of-control blaze we’re all familiar with.

Once this blaze begins, the only thing we can do is ride it out. Hurricanes (also known as cyclones in the southern hemisphere and typhoons in the western Pacific) have a minimum wind speed of 74 mph and move at an average of 15 to 30 mph. When a system crosses the Lesser Antilles threshold and makes a turn to the right, the normally wave-starved East Coast buzzes with activity and anticipation. Whipping, sideways rain; boarded windows and barricades; evacuation orders and emergency vehicles; and an ocean transformed from tranquil to treacherous in a matter of minutes—the coastline comes alive. Anywhere from the Caribbean to Canada could be slam-dancing with swell.

A hurricane wave is different from its long-distance cousins. Swells created thousands of miles away make for organized sets of three to four waves, fifteen to twenty seconds apart. But hurricane swells, often created only a few hundred miles away, make a more continuous train of waves, generally no more than eight to ten seconds apart. It’s not uncommon to see as many as fifteen waves in a single set during a hurricane swell—with little rest between them.

These swells are also more accurate. While large storms from the northern and southern hemispheres spray out broad bands of swell like a garden hose, hurricanes can deliver waves with laser-like precision—in some cases only a few miles wide. South Florida surfers will likely never forget the day Hurricane Isabel sent swell through the narrow Providence Channel in the Bahamas and delivered large, Hawaiian-style surf specifically to Delray Beach in 2003. As surfers at Delray raved, locals at nearby Pompano and Palm Beaches wouldn’t have had a clue. The conditions at their beaches—just a few miles to the north and south of Delray—were as small as a typical summer day.

Each new hurricane is another wildcard from the deck. One—like Felix in 1995—might be an incredible wave machine, stalling off the coast of North Carolina, slowly making its way northwest, and never reaching landfall. As Felix spun 200 miles off the coast with winds up to 140 mph, it generated huge swells all the way to Newfoundland and eventually to Iceland and beyond. One offshore Canadian buoy recorded swell heights at 82 feet. Damage: relatively minimal.

Another, like Andrew in 1992, is more of a wrecking ball. Like so many destructive hurricanes, Andrew missed that right turn in the Caribbean and made landfall in the Bahamas, Florida, and Louisiana as a Category 5. Sustained winds: 175 mph. Massive storm surge up to 23 feet. Dozens of deaths and $40 billion in damage.

Both examples show how fast a hurricane can turn on us. One minute, a hurricane’s transformative effect on the ocean has us running toward the beach. The next, it has us running toward the hills.