So far, the 2017 Atlantic hurricane season hasn’t been much to write home about. While there have been more storms than usual, they’ve all been pretty dinky and short-lived. But forecasters expect that to change in the coming weeks as the peak of the hurricane season arrives.
Favorable water temperatures and winds mean there’s “the possibility now that the season could be extremely active,” featuring as many as five major hurricanes, Gerry Bell, lead seasonal hurricane forecaster for the National Oceanic and Atmospheric Administration said Wednesday.
There are already indications that activity has already picked up, with Tropical Storm Franklin making its second landfall in Mexico earlier this month after strengthening into the first hurricane of the season.
Watch the swift intensification of Tropical Storm #Franklin as the storm pushed out over the Bay of Campeche via mi… https://t.co/lyW4KMik6Q— Doc V (@Doc V)1502281513.0
Such storms bring heightened concerns for storm surge and flooding—as Hurricane Matthew delivered across a swath of the Southeast last year—particularly as rising seas driven by climate change have exacerbated such impacts. Other impacts of global warming on hurricanes are less clear, though scientists think that while the number of overall hurricanes may decline, more powerful storms will account for more of that total.
So far this season there have been six named storms, including only the second April storm in the satellite era. While this is a bit busier than normal, most of these storms were fairly weak and didn’t last very long. Some of them probably wouldn’t have even been noticed as tropical storms before the advent of satellites, Phil Klotzbach, a hurricane researcher at Colorado State University, said.
Tropical Storm Franklin is the most robust storm of the Atlantic season so far. It raked across the Yucatan Peninsula yesterday before emerging over the Bay of Campeche and strengthening. It is expected to become a hurricane—the first of the season—before it makes landfall overnight near Veracruz.
The busiest part of the hurricane season lies ahead, though, with nearly 90 percent of hurricane activity historically falling between late August and early October.
They are predicting eight to 13 more named storms to form during the rest of the season, for a total of 14 to 19. Of those, 5 to 9 are expected to become hurricanes and 2 to 5 major hurricanes, defined as those that reach Category 3 status or higher. An average season has 12 named storms, 6 hurricanes, and 3 major hurricanes.
The reasons for the expected flurry of activity are the favorable conditions in the tropical Atlantic, where most storms form.
Ocean temperatures are above average, providing plenty of fuel for the convection at the center of storms, and wind shear, which tends to cut off storm development, is low. The chances of an El NiÃ±o developing have dropped since May, bolstering the forecast as El NiÃ±o tends to cause the winds that stymie storms.
There have also been a few storms forming in the tropical Atlantic, which tends to portend an active season ahead.
“If you’re going to have an active season, that’s’ where conditions are going to be conducive,” Bell said.
A separate forecast by Klotzbach and his colleagues at CSU also predicts an above-average season, with 16 named storms, eight hurricanes and three major hurricanes.
Forecasters can’t say, though, where such storms might make landfall, as that depends on localized weather patterns that can’t be predicted that far out.
“You’re not going to predict that a season in advance; you couldn’t even predict a day in advance” with the little jog that Hurricane Matthew took last year to avoid making landfall in Florida, Klotzbach said. His forecast does, though, give a 62 percent chance of a major hurricane making landfall somewhere along the U.S. coast, given historical odds.
Forecasters are watching a storm system east of the Caribbean that could provide the first chance for a hurricane to hit, as there is some indication that it could develop and affect the U.S. coast. Whether it will develop into tropical storm or a hurricane, how strong it might get and its likely path are all still uncertain. (Tropical Storms Cindy and Emily did impact the U.S. this season, with Emily, both causing flooding along the Gulf Coast and Florida, respectively.)
If a major hurricane does strike the U.S. this year, it will be the first to do so since Hurricane Wilma in 2005. Of course, a hurricane doesn’t have to reach that technical threshold to do considerable damage when it hits land, as both Hurricane Matthew and Hurricane Sandy made clear. The storm surge and flooding from Matthew killed 34 people and caused $10 billion in damage in the U.S. alone, while Sandy was the second costliest in U.S. history (behind only Katrina).
The damage from such storms is only expected to rise as climate change continues, thanks to rising sea levels that exacerbate storm surge and heavier rains that lead to flooding.
In the future, scientists project that while there will be fewer storms overall, more of those that do form will be at the strongest end of the spectrum, like Hurricane Andrew, the last Category 5 to hit the U.S., more than 25 years ago. Major hurricanes have already increased in the Atlantic since 1970.
There is concern that the lull in major hurricane strikes could make any strikes now worse, particularly with the large influx of people to coastal areas, who may not have experience with such storms. For that reason, emergency managers and hurricane experts caution coastal residents to prepare now.