Tropical Storm Marco—which was a Category 1 hurricane for less than 24 hours over the weekend—is about to hit the Louisiana coast, and locals won’t have much time to recover before the next storm hits.
Marco hit its peak intensity on Sunday evening, so though it won’t make landfall as a hurricane, it will continue to bring significant rains, especially to Louisiana and Texas. There may be a tornado risk farther inland as well. And just because it’s now a tropical storm doesn’t mean Marco can’t bring life-threatening conditions. Winds may still be above 40 miles per hour and there are storm surge warnings across most of Louisiana and parts of Alabama.
#Marco has weakened overnight but is still a threat to portions of the northern Gulf Coast. The Monday morning Key Messages are below. The latest storm forecast is at https://t.co/tW4KeFW0gB and your local weather is at https://t.co/SiZo8ohZMN pic.twitter.com/QVhrvRWM1V
— National Hurricane Center (@NHC_Atlantic) August 24, 2020
Meteorologists expect Marco to hit on Monday, but it’s likely to shift westward due to a phenomenon called the Fujiwhara effect. When tropical storms get within about 870 miles of one another, they start to interact. Generally this means that one storm will weaken while the other strengthens. In some cases, the weakening storm can get stalled when it would otherwise peter out, since the two swirling vortices can start to circle around each other. That means longer periods of rain and wind across an extended area. Sometimes the larger storm absorbs the smaller one, but they can also merely spin together briefly before heading off on their own paths. It’s very rare for two small storms to combine into one enormous one.
However much they end up interacting, we do know that Tropical Storm Laura is barreling toward the gulf and is strengthening as it goes. As of Monday morning it was near central Cuba, and should enter the Gulf of Mexico early Tuesday morning. The warmer-than-average waters there are expected to intensify the storm into a full-fledged hurricane. Meteorologists are cautioning that we could be looking at a Category 3 storm by the time Laura makes landfall late Wednesday or early Thursday.
All of this means that the Louisiana coast, eastern Texas, and western Alabama could be looking at a long period of storm surges, heavy rainfall, and strong winds.
It’s extremely rare to have two storm systems in the Gulf of Mexico at once. It last happened in 1933, when the storms Treasure Coast and Cuba-Brownsville (we didn’t have the current naming system in place back then) made landfall on exactly the same day. One hit Texas as a Category 3 storm, while the other hit Florida as a tropical storm. There were also two storms that occupied the gulf in June, 1959, but both were small—only one was designated with a name.
Right now it’s looking unlikely that Marco will re-intensify back into a hurricane, but the Fujiwhara effect could manage to do just that. If so, it would be the first time on record that there were two full hurricanes in the Gulf of Mexico at the same time.
This may feel like yet another way in which 2020 is a catastrophic year (and it is), but the truth is this has been brewing for a long time. The growing climate crisis is fueling stronger, more frequent storms and this year is just the latest in a long line of record-breaking hurricane seasons.
This year’s hurricane season is further complicated by the COVID-19 pandemic, which is actively spreading in states along the Gulf of Mexico. Residents have been urged to get tested ahead of evacuation and shelter in place orders, and to wear masks and practice social distancing as much as possible.