Atlantic hurricane season had 5 major storms, including deadly Helene

The Atlantic hurricane season ends Saturday, leaving in its wake catastrophic damage in the Caribbean and southeast United States but little direct impact on Long Island.

The National Oceanic and Atmospheric Administration recorded 11 hurricanes, five of them major with winds exceeding 111 miles per hour.

They included Helene, a late September system that barreled from Florida into the Appalachians, whose toll — more than 230 dead and damage estimated at more than $50 billion — likely will make it the deadliest hurricane to affect the continental U.S. since Katrina in 2005, according to NOAA.

The death toll included more than 100 verified storm deaths in North Carolina alone, according to the North Carolina Department of Health and Human Services.

Long Island was outside Helene’s track, and the weather event that caused perhaps the highest impact this year was not a hurricane but a storm on began Aug. 18 and continued into the next day that dumped around 10 inches of rain in places on the North Shore of Suffolk County, flooding homes and businesses, infrastructure and resources like the Smithtown Library’s historical archives.

Long Island officials have said the storm damage may total $100 million, Newsday previously reported.

"This was not associated with any tropical storm," NewsdayTV meteorologist Rich Von Ohlen said of the weather event. "It just occurred over the same area for several hours."

It was the ninth successive hurricane season with above average activity, according to the United Nations’ World Meteorological Organization. An average season produces 14 named storms, seven hurricanes and three major hurricanes.

Climate change, including historically hot ocean waters whose heat fuels the tropical cyclones that can develop into tropical storms and hurricanes, is priming conditions for extreme weather events like heat waves and heavy rainfall, though the impact is uneven across the planet, experts say.

While other, cyclic factors are also at play, "there has definitely been an increase in sea surface temperatures from the Gulf of Mexico through the south and central Atlantic that has set the stage ... for hurricanes in the past few decades," Von Ohlen said.

"What we’re seeing, in recent years, is that inland effects from major hurricanes persist enough to cause devastation," the meteorologist added. "It’s affecting places like the Appalachians, places that aren’t usually thinking about tropical storm or hurricane landfalls, places that are not easily accessible, hilly areas where the water rushes down." 

Meteorological evidence does not indicate that a hotter planet will result in more storms in the Atlantic, but rather that the ones that do occur may be stronger, Jamie Rhome, deputy director of the National Hurricane Center in Miami, said in a phone interview Friday.

"The behavior of storms changes," he said. "They produce more rain, they produce more storm surge because of the background rise in sea levels, and some evidence suggests that storms hang on to their intensity farther north."

In the case of Helene, according to NOAA, at least three different rapid attribution studies found rainfall associated with the hurricane was "higher due to climate change than it would have been without it." Attribution studies analyze how climate change may influence a weather event's intensity and likelihood of occurring. 

One of the studies, by the World Weather Attribution Group, a cooperative of researchers from several climate science institutions, found rainfall associated with Helene was about 10% heavier due to climate change and high rainfall totals before the hurricane were about 40% more likely.

Those "predecessor rain events" were significant because they saturated the ground and swelled rivers even before Helene hit. That study also found continued global warming would make devastating rainfall events like those associated with Helene 15 to 25% more likely.

As Atlantic hurricane season winds down — the next season starts June 1 — forecasters are expected to turn their attention to nor‘easters and other winter weather events. NOAA’s winter outlook, released in October, called for wetter-than-normal conditions in the northern U.S., with warmer than usual temperatures for Long Island and the eastern seaboard.