As the first week of summer delivers a heat wave to parts of the U.S., it also brings “incredibly high temperatures” to the Gulf of Mexico, leading experts to warn that if such hot weather persists, it could spell trouble for the still-nascent hurricane season.
On Wednesday, some 155 million people across the country were expected to face high temperatures above 90 degrees, with 17 million set to experience highs above 100, according to NBC News meteorologist Kathryn Prociv.
The hot weather will stretch through Thursday and possibly into the weekend across the Southeast, Gulf Coast and Florida, Prociv said, where Atlanta and Florida cities Pensacola, Tallahassee and Jacksonville are all forecast to hit or come close to their first 100-degree day in three years. Other Southern cities — including Dallas; Houston; New Orleans; Memphis, Tennessee; and Nashville, Tennessee — could set record highs in the coming days, Prociv said.
While undoubtedly unbearable on land, such long-duration heat events also make the water off the coast incredibly hot. The recent heat wave has caused the Gulf of Mexico water temperature to spike several degrees above average.
The minimum temperature threshold for maintaining a hurricane is 26 degrees Celsius (about 79 degrees Fahrenheit), said Nan Walker, a professor of oceanography and coastal sciences at Louisiana State University.
“We’re 3 to 4 degrees above that, or more,” she said. “So we’re well above what a hurricane needs to survive.”
That's concerning because warm Gulf water — though not the sole cause, meteorologists and climatologists say — can fuel hurricanes, making them stronger.
“That’s really the biggest impact, the potential for a rapid intensification,” said Matthew Rosencrans, lead seasonal hurricane forecaster at the National Oceanic and Atmospheric Administration's Climate Prediction Center. “So as the storm gets close to the coast, it’s just going to have that much more energy to work with.”
Last month, forecasters with NOAA said there is a 65% chance of an above-normal hurricane season along the Atlantic seaboard. Forecasters predict — with 70% confidence — between 14 and 21 named storms, meaning with winds of 39 mph or higher. They expect between six and 10 hurricanes. Hurricane season began June 1.
“We’re already really warm, and we’re only at the beginning of, you know, of true summer,” said Jill Trepanier, a hurricane climatologist and associate professor at LSU.
“It’s good that right now we don’t have any disturbances or any tropical cyclones expected within the next five days in the region,” she said.
Last year, Hurricane Ida underwent a period of rapid intensification, growing from a Category 1 to a Category 4 storm in 24 hours as it moved across unusually warm water in the Gulf Coast just before hitting land.
The ferocious storm crashed ashore in Port Fourchon, Louisiana, and battered several other parts of the state, pulling roofs from homes, flooding streets, snapping trees and leaving the metro New Orleans area without power for days.
There are no current forecasts for storms that could take advantage of the existing warm temperatures.
“But if there was one, everybody would be talking about the extra-warm water that it would have in front of it,” Prociv said. “We wait to see with all of this heat, how long does that extra-warm water stick around.”