The Atlantic Ocean is packed with storms. What's going on?

A September 13 image of the Atlantic Ocean taken by the GOES-East satellite.
A September 13 image of the Atlantic Ocean taken by the GOES-East satellite.
Image: noaa
2017%2f12%2f04%2f7d%2fmarkpic.c6031By Mark Kaufman

The Atlantic Ocean is alive.

Including Hurricane Florence, there are currently four named storms — tempests with winds of at least 39 mph — churning in the Atlantic. This ties the record for the most named storms in the Atlantic at any one time. 

And there could be more: There’s yet another collection of thunderstorms off in the Gulf of Mexico that has a decent, 50 percent shot, of becoming the fifth well-developed, named storm. 

While there’s substantial evidence that climate change is having a major impact on the behavior of hurricanes, this current flurry of storms falls within the realm of expected activity for this time of year. 

After all, it’s the peak of hurricane season.

“Hurricanes and tropical activity often comes in ‘bursts’ (internal variability), and that’s what we’re seeing now, coincident with the peak of hurricane season,” Falko Judt, a research meteorologist at the National Center for Atmospheric Research, said via email. 

“This is the time of year when we expect a lot of activity — though not always 4 simultaneous named storms!” added Brian McNoldy, a senior research associate at the University of Miami’s Rosenstiel School of Marine and Atmospheric Science.

During the peak of hurricane season, there’s generally a more favorable environment for these types of storms to form than at other times of year. 

For one, water in the tropics are at their warmest in September, and hurricanes can’t survive without warm, bathtub-like waters. Secondly, wind shear — winds that hit hurricanes from their sides and break them apart — is typically lighter this time of year.

Hurricane Florence has been feeding off some unusually warm ocean waters, which played a role in its sustained and atypical westward trek towards the Carolinas. 

“Florence was by far the storm that could best take advantage of higher water temperatures, given its path,” said Judt.

Sea surface temperatures in the Atlantic showing cooler tropical waters.

Sea surface temperatures in the Atlantic showing cooler tropical waters.

But overall, warmer waters aren’t responsible for stoking the other storms in the Atlantic, which form in the tropics. 

In fact, “most of the tropical Atlantic is actually colder than normal right now,” Phil Klotzbach, a hurricane scientist at Colorado State University, said over email.

Instead, Klotzbach notes that wind shear, a notorious hurricane-killer, “has been generally quite low.”

What’s more, Klotzbach said that a seasonal weather pattern near the equator, the Madden-Julian Oscillation (MJO), has driven wind shear down to “anomalously low” levels. But in about a week, the opposite will occur, likely leading to less cyclone activity in the tropics, he said. 

Although this burst in storm activity — which will potentially break the record for named storms at any one time — is driven largely by expected weather patterns, individual storms like Florence can be enhanced by climate change.

Earth’s average temperature is increasing, and it’s well understood that warmer air is capable of holding more water

Specifically, for every 1 degree Celsius, or 1.8 degrees Fahrenheit, of warming, the air can hold 7 percent more water. This means storms can suck up more water from the air, giving them more fuel for heavier downpours. 

Perhaps worse is the reality that storms around the world are slowing down, as was recently illustrated by NOAA atmospheric scientist Jim Kossin. 

“Nothing good can come of a slower storm, Kossin explained.

Hurricane Florence is forecast to do just this as it stalls over the Carolinas this weekend. The National Hurricane Center expects extreme deluges and a good shot at toppling rainfall records.

There is, however, some good news. 

Once this batch of storms dies off, “it might be a while until the next one,” said McNoldy.

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