Forecast of 'near-normal' hurricane season isn't certain, experts say

Photo of Nick Powell

After a relatively tame 2018 hurricane season in the year after Hurricane Harvey swept through southeast Texas, forecasters believe major storm activity could be near or slightly above normal in the coming months.

The National Hurricane Center predicted Thursday that a near-normal Atlantic hurricane season is most likely this year, meaning a likely range of nine to 15 named storms (winds of 39 mph or higher), of which four to eight could become hurricanes (winds of 74 mph or higher), including two to four major hurricanes (category 3, 4 or 5; with winds of 111 mph or higher). Hurricane season begins June 1.

A near-normal season, of course, could still be hazardous for southeast Texas residents, who are two years removed from Hurricane Harvey, a Category 4 storm that dumped 51 inches of rain in some parts of Greater Houston. That storm damaged 100,000 homes and left around 80 people dead in Texas, most in the Houston-Galveston area.

Matt Lanza, a forecast meteorologist in Houston’s energy sector and the managing editor of the website Space City Weather, said National Hurricane Center predictions are careful not to forecast with certainty. While the likelihood of a “near-normal” hurricane season was assessed at 40 percent, the chance of a season slightly above or below normal was judged to be 30 percent.

“There’s a lot of hedging in there. That’s kind of the reality with these sort of things; hurricane forecasting is not a perfect science yet,” Lanza said. “It’s a good incentive for people to not let their guard down despite a normal to below-normal potential season.”

Experts generally agree that the ongoing El Niño event, in which surface temperatures become warmer than normal in the equatorial Pacific Ocean, portends a quieter hurricane season.

But Phil Klotzbach, a research scientist for Colorado State University’s Tropical Meteorology Project, said the intensity of El Niño is subject to debate, and the phenomenon might not suppress hurricane development as much as it did in 2018.

“What (El Niño) does is basically it changes the circulation of the tropics in such a way that you get strong westerly winds that shear and tear apart hurricanes in the Atlantic, and especially in the Caribbean,” Klotzbach said. “The magnitude of the El Niño definitely plays a role; it’s not just that you hit this magical threshold and nothing happens.”

Current Atlantic Ocean temperatures are also relatively warm, setting up a scenario where the competing influences of a warmer Atlantic and warmer Pacific could make the difference between an active or tame hurricane season.

“The temperatures tend to be slightly above normal across the tropical Atlantic right now,” said John Nielsen-Gammon, a Texas state climatologist at Texas A&M University in College Station. “That would slightly favor an active season.”

Climate change is also a significant factor when evaluating storms in the Gulf Coast region, past and present. Higher water temperatures in the Gulf of Mexico mean that storms as big as Harvey in 2017 have an energy source of sorts to rely on. Even as the surface temperatures cooled as Harvey made its way back into the Gulf, the deeper water temperatures were warm enough to sustain its force.

However, experts warn that the temperatures in the Gulf do not typically correlate with an active or inactive hurricane season. Hurricanes over the Gulf form from varying processes.

Some, like Hurricane Ike in 2008, form like a typical hurricane off the coast of western Africa and make their way across to the Gulf. Other storms, like Harvey in 2017 or Michael, a Category 5 storm that devastated Florida in 2018, spin up in the Gulf itself.

“What really determines whether you actually get a hurricane forming in the Gulf in a given year is not so much the sea surface temperature but whether you happen to get the right kind of upper level disturbance moving out of the Gulf and organizing the thunderstorms,” Nielsen-Gammon said, adding that those types of storms are far less predictable.

Whether the Houston-Galveston region is better prepared to handle a storm of a Harvey magnitude two years later remains to be seen.

Harris County residents last November approved a $2.5 billion bond package to build over 230 projects designed to mitigate flooding, from widening bayous and channels to excavating storm retention basins. Much of that work, however, is in preliminary stages.

Fort Bend County has budgeted $3 million for an 18-month study of potential drainage improvments. Galveston County leaders have focused for months on the possibility of a coastal barrier system proposed by the U.S. Army Corps of Engineers that would include 71 miles of dunes, gates, and levees. But construction on any such barrier is still years away and would require a massive amount of federal money.

The slow movement of these major flood mitigation projects adds up to a region that has not changed much since Harvey made landfall.

“The rainfall flooding like a Harvey, it’s an evolving, ongoing thing where maybe we’re a little bit better off than we were a couple years ago, but I don’t know that the average Houstonian or southeast Texan is really going to notice it at this point,” Lanza said.