With the nation focused on hurricane recovery in Texas, the Atlantic Ocean was priming itself for peak season, greasing a path for newly formed Tropical Storm Irma’s westerly slide toward the Caribbean.
Irma, the ninth named storm this year, is no immediate threat to land, but was introduced by the National Hurricane Center on Wednesday when a robust circle of thunderstorms blew up 420 miles west of the Cabo Verde Islands.
Although it’s about a month early on average for an “I”-named storm, warm water and light wind shear are expected to coax Irma to hurricane strength by week’s end.
“Unlike previous systems that came this route this year, there isn’t much wind shear or dry air in the way of Irma at all,” said Jonathan Erdman, a senior digital meteorologist at Weather.com. “There’s a reason why there’s a peak to the season, because the optimal conditions tend to maximize right around the end of August and into September.”
As of the Wednesday 5 p.m. advisory from the National Hurricane Center, Irma was a 60-mph tropical storm, heading west at 15 mph. The official five-day forecast brings it to Category 2 strength with 105 mph winds within three days, and keeps it on a track toward the Lesser Antilles.
This is the first time the name Irma is being used in the Atlantic. Irma replaced Irene — a name stricken from the rotating list after the 2011 hurricane season where damaging Hurricane Irene flooded into New Jersey, Massachusetts and Vermont.
The hurricane center also identified another area of concern Wednesday: a disturbance that could move off the coast of Mexico and into the southwestern Gulf that could cause more grief to Gulf Coast states, including areas of southeastern Texas where Harvey has dumped 52 inches of rain, according to the Weather Prediction Center.
Hurricane forecasters gave that disturbance a 20 percent chance of developing over five days. They said it would be slow to organize and that it’s too early to tell how much rain it could bring.
“Whether, or to what extent, it would affect the Harvey-impacted areas is unknown,” Erdman said. “But it’s something we have to watch for in the entire Gulf of Mexico.”
If it becomes a named storm, it would be Jose.
As for Harvey, it maintained tropical storm strength Wednesday after making landfall in Louisiana, but was expected to weaken as it moves inland.
Phil Klotzbach, a hurricane researcher with Colorado State University, said not to read too much into the early arrival of Irma as compared to the historic average. Advanced technology allows more storms to be identified today than in the past, so it’s not a true comparison.
A better measure that takes into account intensity and duration of storms — called Accumulated Cyclone Energy — is about normal for this time of year even with Category 4 Hurricane Harvey.
“I think we’re going to jump up big time with Irma, though,” Klotzbach said. “If the models are right, (Irma) has the potential to be a pretty long-lived hurricane.”
Most hurricane forecasts have increased their number of predicted storms as this season progressed. Last week, The Weather Company hiked its forecast to a total of 17 named storms, nine hurricanes, including four major hurricanes of Category 3 or higher.
Erdman said he’s always wary of “I”-named storms because they typically form during the peak of the season when they can take advantage of ideal conditions for strengthening.
With Irma, he foresees two scenarios.
If the Bermuda-Azores High — a sprawling high pressure system that shimmies closer to Bermuda or to the Azores, depending on ocean temperatures — is weak and closer to the Azores, hurricanes tend to curl around the western edge of the clockwise-swirling high away from the U.S.
If the high is strong and closer to Bermuda, storms are forced farther south and west, and become a bigger threat to the U.S.
“It’s a good time to prepare and make sure your hurricane plan is in place because if the scarier scenario holds, it could be a threat as soon as the week of Sept. 10,” Erdman said. “No one is off the hook right now.”