Danielle Continues Streak of Early Season Tropical Storms

Tropical Storm Danielle became the fourth named storm of the 2016 Atlantic hurricane season on Monday, the earliest on record that the fourth tropical storm of a season has formed.

Danielle, which developed in the Bay of Campeche off the east coast of Mexico, beat 2012’s Tropical Storm Debbie, which formed on June 23 of that year. The average date for the fourth named storm to appear (based on data from 1966 to 2009) is August 23, hurricane researcher Phil Klotzbach of Colorado State University said.

Earlier this month, Tropical Storm Colin set a record for the earliest third named storm of a season, and Tropical Storm Bonnie formed a few days before the official June 1 start to the season. The first storm of the season, Hurricane Alex, was the first hurricane to form in January since 1938.

Danielle formed thanks to a combination of relaxed wind shear and warm ocean waters, Klotzbach said.

A drop in wind shear (or the change in direction and speed of winds between different levels of the atmosphere) has been a noticeable feature of the larger storm environment so far this year compared to last, when an El Niño kept wind shear levels high. That El Niño has since dissipated, and a La Niña, which tends to bolster storm formation, could form by the peak of the season.

“All in all, the environment is more conducive this year than last year, primarily due to the lack of El Niño,” Klotzbach said in an email.

This early activity doesn’t tell much about what might happen later in summer when storm activity typically peaks, he cautioned.

“Pretty much the key is to see if we get [storms forming] out of the deep tropics in July,” he said. “That’s typically a harbinger of a very active upcoming hurricane season.”

However, researchers are studying the possibility that rising ocean temperatures caused by global warming could lengthen the hurricane season, leading to more storms at its tails. Some research on recent trends suggests the hurricane season might be getting longer, but projections from climate models have had mixed results.

Danielle has already brought heavy rains to parts of eastern Mexico and was expected to make landfall later Monday. The U.S. National Hurricane Center predicted that rains would total 6 to 10 inches over parts of the Mexican states of Veracruz, Tamaulipas, San Luis Potosi, Queretaro, Hidalgo, and northern Puebla, with the potential for up to 15 inches in higher terrain.

One of the key concerns from such rainfall is flash flooding and mudslides.

The Weather Channel reported that the storm would also bring a high risk of rip currents to parts of the coast of Texas.

Overall, the National Oceanic and Atmospheric Administration has predicted 10 to 16 named storms will form this season, with four to eight becoming hurricanes and one to four of those becoming major ones.