South Florida marine heat wave could mean trouble this hurricane season
With surface temperatures in the 90s in some areas off South Florida's coast, AccuWeather forecasters warn that the marine heat wave is practically "inviting" a large system to hit the state.
Sea surface temperatures on July 10, 2023. The area off the coast of southwest Florida shows temperatures had reached 91 degrees Fahrenheit (32.5 degrees Celsius). (NOAA)
The marine heat wave off the coast of Florida could prove to be detrimental not just to the local ecosystem but also to residents of the peninsula's coast hoping to avoid explosive storms this hurricane season.
Surface level temperatures around Florida and the Keys are roughly 4-6 degrees Fahrenheit higher than what would be considered normal for this time of the year in what meteorologists are declaring a marine heat wave. This is defined as a period of unusually high ocean temperatures that can have a significant impact on marine life as well as coastal communities and economies.
Water temperatures in the area typically begin to rise in late March and April, but this year the warming has increased intensely. Bright orange splotches blossomed off Florida's southwest coast on ocean temperature maps as buoys in the area recorded surface temperatures closer to what they might be at the peak of hurricane season, leading meteorologists to grow concerned over what this could mean for the next few months in the Atlantic basin.
What forecasters "fear the most" about the warm waters
High ocean temperatures are just one factor in a tropical system's formation. Early in the season, Saharan dust in the mid-levels of the atmosphere creates hostile conditions for these systems to form. It's for this reason that forecasters aren't necessarily concerned about storms developing earlier, but rather that the warming waters could fuel storms that enter the area near Florida when conditions become more favorable for development.
"This is just inviting a big system to hit the state again this year. We already know how warm the water is across the main [tropical] development area now," AccuWeather Lead Long-Range Meteorologist Paul Pastelok said.
There are currently no active tropical systems in the Atlantic basin as of Thursday afternoon, but marine heat waves can sometimes last for months or years. Pastelok warned that it takes a big event or change in the weather pattern to lower the water temperatures once more, and he expects the warm waters to last throughout the season.
In March, AccuWeather forecasters projected that the 2023 Atlantic season could produce 11–15 named storms -- around the 30-year average of 14 -- two to four of which could lead to direct impacts on the contiguous United States, including Puerto Rico and the U.S. Virgin Islands. The warm waters around Florida now could create an environment that allows a tropical system to rapidly intensify more easily.
"Dust and higher-than-normal shear is holding back tropical development currently and probably for most of July," Pastelok said. "But what happens when this eases back and a tropical wave or disturbance reaches this area? [We] need to watch for rapid intensification of storms this year. There may not be a lot of storms, but the ones that get into this area could explode."
A tropical system rapidly intensifies when its maximum sustained winds increase by 35 miles per hour (30 knots) within a 24-hour period. Hurricane Ian, a storm that practically became the face of the 2022 Atlantic hurricane season, underwent rapid intensification in late September as it charged toward Florida.
This satellite image taken at 3:06 p.m. EDT and provided by NOAA shows Hurricane Ian making landfall in southwest Florida near Cayo Costa, Fla., on Wednesday, Sept. 28, 2022, as a catastrophic Category 4 storm. (NOAA via AP)
According to a post-storm analysis by the National Hurricane Center, meteorologists found that peak winds in the eyewall had reached 160 mph, meeting the criteria of a Category 5 hurricane, before it lost some wind intensity and slammed into Florida as a strong Category 4 hurricane.
"It exploded, intensified dramatically. Why? Because of very warm water," AccuWeather hurricane expert Dan Kottlowski told AccuWeather National Reporter Bill Wadell. "And again, we saw that with Ida, we saw that with Laura, we saw that with Dorian. We saw that even going back to Harvey and going back to Irma. All those storms went over very warm water and intensified very, very quickly. We call it rapid intensification. That's our biggest fear."
What's turning up the heat
This is the highest water temperatures in the area have been this early in the season with temperatures in the Florida Keys upwards of 90 degrees, according to experts like Kottlowski and Dillon Amaya, a climate scientist and research scientist at the NOAA Physical Sciences Laboratory in Boulder, Colorado, who studies marine extremes.
One buoy near Bob Allen Keys, Florida, located within the Everglades National Park just south of the Florida mainland, recorded a water temperature as high as 96.3 degrees Monday, July 10, at 4 p.m. EDT, according to data from the National Oceanic and Atmospheric Administration (NOAA).
While July sea surface temperatures in the low 90s aren't completely atypical near the Florida Keys, they tend to trend more toward the upper 80s closer to the peninsula, according to AccuWeather Meteorologist Mary Gilbert.
"Right now, sea surface data in the Florida Keys indicates temperatures are in the middle 90s," she said. "Closer to Miami, some sea surface temperatures are at or just above 90."
Beachgoers take a dip in the Atlantic Ocean at Hollywood Beach, Monday, July 10, 2023, in Hollywood, Fla. Water temperatures in the mid-90s (mid-30s Celsius) are threatening delicate coral reefs, depriving swimmers of cooling dips and adding a bit more ick to the state's already oppressive summer weather. (AP Photo/Wilfredo Lee)
"A lot of that's due to the fact that we really have not had anything to really get rid of the real warm water over the winter in a lot of places," Kottlowski said.
Amaya added in an interview with Wadell that the impacts of climate change may also be exacerbating the extreme reach of the temperatures.
"One thing that we know for sure is that oceans are taking up 90% of the excess heat associated with global warming, so we know that marine heat waves are getting warmer and warmer and warmer as associated with this long-term warming trend," Amaya said. "So, it's too early to say whether this particular heat wave was triggered by global warming, but it was certainly made warmer by global warming."
"We're in hot water"
Data from NOAA shows that marine heat waves are unfolding on a global scale, setting records that are decades old. The most pronounced one is located off the coast of South America near Peru; however, other events have also been noted in the eastern Atlantic, the north-central and southwestern Pacific as well as the Indian Ocean. The marine heat wave in the Gulf of Mexico now joins their ranks.
As of late June, NOAA scientists estimate that surface temperatures of 40% of the global ocean were high enough to meet the criteria for a marine heat wave, and a forecast by the Physical Sciences Laboratory projects it will increase to 50% by September.
A map from NOAA's Physical Sciences Laboratory highlighting the magnitude of marine heat waves from June 13, 2023, to July 13, 2023. (NOAA Physical Sciences Laboratory)
"No doubt, we're in hot water," Amaya said in a press release. "In our 32-year record, we have never seen such widespread marine heat wave conditions."
These heat waves should serve as red flags, he told Wadell, as the impact of one marine heat wave, let alone several, will have a heavy impact.
"There's something to be concerned about. Global marine heat waves like this are going to lead to impacts, whether that's on marine ecosystems, whether that's on the strength of developing storms, we'll see the impacts of these down the line," he said. "It may not be apparent for several weeks, or maybe even months. But these impacts are real, and they're likely coming, and it's something that people should be prepared for."
Additional reporting by AccuWeather National Reporter Bill Wadell.
Want next-level safety, ad-free? Unlock advanced, hyperlocal severe weather alerts when you subscribe to Premium+ on the AccuWeather app.AccuWeather Alerts™ are prompted by our expert meteorologists who monitor and analyze dangerous weather risks 24/7 to keep you and your family safer.
Report a Typo
