Did you know there’s a tropical storm right now in the Atlantic? It’s true. But it’s a bit farther south than you’re probably accustomed to.
A rare tropical depression formed off the South American coast Saturday, according to the Brazilian Navy Hydrographic Center. On Sunday, the system became a tropical storm. It was named Iba, marking the first time the agency has drawn upon its list of tropical cyclone names for a storm of purely tropical pedigree. The previous six storms that were named were “subtropical” cyclones, meaning they shared a mix of tropical and non-tropical characteristics. The list of storm names became operational in 2011.
It’s also the first full-fledged tropical storm to spin up in the South Atlantic in nearly a decade, since Tropical Storm Anita’s brief dance in 2010.
Tropical Storm Iba is anchored about 150 miles east of Brazil’s Espirito Santo state. At the storm’s center, 50 mph winds gusting to 65 mph will continue to stir up rough seas, with wave heights topping 15 feet. But it will have little effect on land.
Iba’s precipitation shield looks to remain largely offshore, its rainbands confined to mainly open waters. Espirito Santo’s capital city, Vitoria, will enjoy bountiful sunshine today and tomorrow, with temperatures hovering just below 90 degrees.
Though Iba’s effects are limited to fish, its weather whimsy is intriguing from a scientific standpoint.
Until relatively recently, it was almost unanimously agreed upon that tropical cyclones couldn’t form in the South Atlantic. The region is characterized by strong wind shear, which can easily tear apart fledgling systems. Water temperatures would usually be too cool to grow or sustain them. And there’s a lack of triggering mechanisms — the “tropical waves” and associated zone of thunderstorm activity needed to spark cyclone development is generally draped well to the north.
But in 1991, things changed. The National Hurricane Center reported an “extremely unusual occurrence, a tropical cyclone over the eastern South Atlantic Ocean.” Satellite data, it said, suggested the swirling mass of clouds “was probably of tropical depression or minimal tropical storm strength.” While it never came close to land, it raised questions as to whether the South Atlantic could cook up a storm after all.
Then came 2004. On March 12, a run-of-the-mill upper-level trough kindled the growth of a gently rotating cluster of thunderstorms along its northern tip. Over the next 10 days, the system acquired tropical characteristics, flourishing in an environment with weak winds aloft and warmer-than-average sea surface temperatures. By March 24, it was “subtropical,” transitioning to fully tropical a day later. On March 26, 2004, the South Atlantic’s first hurricane on record was born, quickly dubbed Catarina as it intensified to a Category 2 beast within 48 hours. It got the name because it came ashore in the Brazilian state of Santa Catarina.
Initially, experts in Brazil and the United States disagreed about Catarina’s status, arguing over whether it should be classified as a hurricane. Those at Brazil’s National Space Research Institute reportedly doubled down days after the system made landfall, asserting that it “was not a hurricane.” Satellite imagery and storm data analyzed in the years since have widely established it as a bona fide hurricane.
Now, 15 years later — to the day — the tropics have again whipped up meteorological mischief. Maybe the South Atlantic will surprise us. It certainly has a few tricks up its sleeve.