The National Hurricane Center is projecting that two hurricanes — Laura and Marco — will swirl above the Gulf of Mexico on Monday. If this comes to pass, it would be a first in more than a century and a half of record-keeping, and a high-impact situation for coastal residents. Such a scenario would severely strain resources amid an already busy hurricane season, when several Southern states are reeling from the coronavirus pandemic.

The busy ocean basin is warm enough that it could even support a significant hurricane, though uncertainty abounds in how the storms will evolve. Meteorological history may be in the making, however.

When Tropical Storm Laura formed northeast of the Leeward Islands on Friday morning, it became the earliest L storm on record, ahead of Tropical Storm Luis, which formed on Aug. 29, 1995. A second system, aiming for the Yucatán Peninsula, is likely to become Marco next. The pair of storms will then converge on the Gulf late this weekend.

Data and history also supports the possibility that the two systems could interact or even dance around one another once they intensify in the Gulf, complicating an already high-stakes forecast.

Something new, and so 2020

Having two hurricanes in the Gulf simultaneously wouldn’t just be rare. It would be unheard of.

“We’ve never had two hurricanes simultaneously in the Gulf of Mexico,” said Philip Klotzbach, a hurricane researcher at Colorado State University, in an email. “We have had two named storms in the Gulf of Mexico on two separate occasions.”

Around midnight on Sept. 4, 1933, as a Category 3 hurricane was making landfall in Brownsville, a tropical storm was traversing the Florida peninsula, according to Klotzbach.

An unnamed storm also spun up in the Gulf at the same time as Tropical Storm Beulah on June 18, 1959. But that’s about it. Despite being one of the most suitable environments for intense hurricanes in the Atlantic, the Gulf is relatively small, at barely 1,000 miles in diameter. This presents complications for storms that attempt to spin up there when competition is close by.

Competitive storms

Getting tropical systems in the Gulf of Mexico is comparatively rare to begin with. The vast majority of long-lived tropical cyclones and hurricanes form over the Atlantic’s Main Development Region, which is an imaginary box to the east of the Lesser Antilles in the tropical Atlantic where the warmest water temperatures overlap with the most conducive atmospheric conditions.

Weather Underground reports that’s where 85 percent of all major hurricanes and 60 percent of named storms originate.

This means that topical cyclones and especially hurricanes in the Gulf of Mexico are just rare enough that it’s not often you’ll see two near the same place at the same time.

Likewise, it would be very challenging for two hurricanes to form simultaneously in the Gulf. Because the Gulf of Mexico barely 1,000 miles across, you would need both systems to be somewhat close to opposite ends of the basin. If they were closer, they might compete for resources and kill off one of the storms.

The best chance to get two hurricanes in the Gulf is for one or more to arrive from someplace else, and for them to be far enough apart to avoid sapping the other storm’s energy.

There is a 150-mile-wide opening between Cancun at the tip of the Yucatán Peninsula and far western Cuba that serves as the entrance to the Gulf. As long as a storm’s center passes through or close to that gap, it has a good chance of surviving. Some storms are able to thread the 130-mile gap between northern Cuba and the Florida peninsula.

An ominous scenario but not a sure bet

What the National Hurricane Center is forecasting is exactly the ominous scenario of two developed cyclones entering the Gulf at about the same time. Tropical Depression 14, likely to be named Marco, is snaking its way up the western entrance, while Tropical Storm Laura will try to enter from the east.

There is a chance that Laura could weaken if it brushes too close to or passes over Hispaniola, but alternatively Laura could strengthen, perhaps significantly, if it remains over mainly open waters.

Tropical Storm Marco, on the other hand, will probably make a run toward hurricane strength, but its future intensity could be limited by a change of wind speed and/or direction with height known as “wind shear.”

Yet there is one scenario that could lead to both storms becoming not only hurricanes but also perhaps intensifying more than the National Hurricane Center is correctly forecasting. It’s called the Fujiwhara Effect.

When tropical cyclones dance

The Fujiwhara Effect occurs when two vortices in close proximity begin orbiting about a common center. It happens with tropical cyclones but has even been observed with tornadoes.

Hurricanes Hilary and Irwin danced over the Pacific in 2017, one eventually overtaking the other in the elegant waltz.

It’s possible that Laura and incipient Marco could dance in the Gulf if their timing and intensity is similar, which could stall Marco’s progress northwestward toward the Texas or perhaps Louisiana coast. Marco, in turn, may be able to intensify more than was originally anticipated, something a few weather models have hinted is a possibility.

Whatever ends up being the case, you can be sure atmospheric scientists will be watching closely this weekend and early next week.

And if you live along the Gulf Coast or in the state of Florida, you should be staying aware of the latest forecast, too.