【Sister Emanuelle】

Stormwaters surged over Grand Bahama International Airport on Sister EmanuelleMonday, turning the runway into a churning sea.

Hurricane Dorian stalled directly atop Grand Bahama Island in the northern Bahamas for around 24 hours, allowing the tropical cyclone to drive ocean water over vast swathes of the 530 square-mile island, home to some 50,000 people. After Dorian strengthened into a monstrous Category 5 hurricane (packing sustained 185 mph winds) over the weekend, atmospheric conditions pinned Dorian over Grand Bahama where the cyclone's strongest winds, around the eye of the storm, pummeled the island.

Hurricane Dorian -- now a Category 2 storm but still a powerful cyclone -- moved just 25 miles over 24 hours, or just about 1 mph. Only one other Atlantic cyclone, Hurricane Betsy in 1965, tracked a shorter straight-line distance over the course of a day, according to hurricane researcher Philip Klotzbach.

At some points, the cyclone didn't move at all. "It virtually stalled on Monday," said Jeff Weber, a meteorologist at the University Corporation for Atmospheric Research. 

Under the right atmospheric conditions, hurricanes, however powerful, can get stuck. Cyclones are controlled by the large scale weather patterns around them, specifically regions of differing pressure known as ridges (zones of high pressure) and troughs (low pressure).

"Hurricanes are like a cork in a stream," said Brian Tang, an atmospheric scientist at the University of Albany.

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These large ridges and troughs in the atmosphere influence the direction and speeds of high atmospheric winds -- winds that ultimately govern where storms go. "If there weren't other winds, hurricanes would just sit there and spin," said Weber.

In Dorian's case, a persistent, dominant ridge called the Bermuda High shifted farther from Dorian to the northeast, and its associated winds weakened too. What's more, the storm got wedged between the Bermuda High and another ridge to the west of the storm. "It's like two people pushing on a rock with equal force," explained Tang. "They canceled each other out."

Unfortunately for the denizens of Grand Bahama and nearby Abaco Island, Dorian parked over populated land. Abaco now looks like a wasteland, with flattened, non-visible homes.

In our planet's complicated, swirling, chaotic atmosphere, it's actually common for weather patterns to get stuck, explained Rosimar Rios-Berrios, a hurricane scientist at the National Center for Atmospheric Research. But it's not every day that the weather event in question is a powerful, catastrophic hurricane. "We tend to notice it more when there's a hurricane," Rios-Berrios said. "It can happen any day."

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For much of Dorian's short life, the dominant ridge known as the Bermuda High, acting like an atmospheric wall, was poised to steer Dorian into Florida. But this zone of high pressure moved northeast.

"If the Bermuda High did not progress to the north and the east, Dorian would have definitely come into Florida," said Weber.

"It's amazing that a pressure field thousands of miles away is determining the fate of millions of people along the Florida coast," Weber added, but noted that this weather system had an unfortunate fate for the denizens of the northern Bahamas.

Now, however, a big trough -- a long zone of relatively lower pressure -- is moving down the U.S. towards Dorian. This will allow the hurricane to ride along the windy edge of the system as it travels off the southeastern coast, explained Weber. Some of these same winds will start to tear apart and weaken the storm, he explained. Though, Dorian will pass through some warmer waters, which could potentially give the storm some renewed strength.

There's also the reality that the storm, though weakened, could still shift slightly west. And that could mean sizable coastal impacts in the U.S. "Even a slight shift to the west could bring the hurricane very close to Florida, Georgia, or the Carolinas," said Rios-Berrios.

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Dorian is not the only recent Atlantic basin hurricane to move slowly. Of note, there's been Florence and Harvey, the latter of which toppled the rainfall record in the U.S. What's more, research has shown that over the last half-century tropical storms have slowed down. That's bad: Slower storms mean bounties more torrential rain -- or surges of ocean water.

But it's too soon to know whether Dorian or the recent storms are part of a slowing trend, or if the trend is continuing. "We don't have enough samples," emphasized Rios-Berrios. "We do have three. I don't think that's sufficient to make any conclusions."

And if the cyclones are continuing to slow down, hurricane researchers have not pinpointed a possible reason why. "We don't have a clear answer yet," said Tang.

But Dorian, while terribly catastrophic for portions of the Bahamas, has certainly been an invaluable opportunity to observe the behavior of a dynamic, changing, and stalling storm system. "If I have learned anything from Dorian, it's that our science has come very far, but we still have a lot more to learn."

"It was a crazy one," said Weber.