Ever since Hurricane Dorian in 2019 and Hurricane Florence in 2018 flooded the Carolinas, the two states have been in an eerie stretch of peace, tropical weather-wise.
Not a single hurricane reached South Carolina or North Carolina at full strength in 2021, and only one, extremely weak tropical storm has reached the Carolinas so far in 2022.
National forecasters say that calm might not last, as the worst part of hurricane season is still ahead. Roughly 90% of tropical weather, especially the most dangerous storms, typically appears in August, September and October.
“If you’re going to make a bet going into the season” on when a big storm will arrive, said Stephen Kebbler, a forecaster in the National Weather Service’s Wilmington office. “It would be in September sometime.”
Why do most hurricanes form in the late summer?
Hurricane season peaks on Sept. 10, with the vast majority of the biggest storms — Category 3 or higher — historically appearing within a week or two of that date.
Tropical weather “ramps up quickly ‘til then, and then after that, it goes down pretty quick,” Kebbler said.
But why? What makes September so different from the rest of the summer?
The biggest factor: Sea surface temperature. The Atlantic and the Gulf of Mexico spend all summer heating up and reach the tipping point when that heat can finally provide enough “fuel” for tropical storms in late August and early September, Kebbler said.
Another issue: Storm activity off the western coast of Africa also tends to ramp up around the same time. Those storms float out into the ocean, build up strength and then head to the Caribbean and North America.
The weather patterns across South Carolina’s coastline are also favorable to storms once they arrive. Right now, the state has a lot of what Kebbler called “lazy” weather: Little wind, slow-moving clouds and storms.
Some of the biggest storms to devastate the Carolinas — Hurricanes Dorian (2019), Florence (2018) and Hugo (1989) — all made landfall within 14 days of Sept. 10.
Fairly soon, though, after Sept. 10, several weather patterns start to interrupt the ability of tropical storms and hurricanes to form. First, air temperatures begin to decline, and cold fronts coming from the north appear more often.
The jet stream also starts to produce greater wind shear, which rips up tropical storms as they start to coalesce.
“That’s something that the tropical storms and hurricanes do not like, is stronger winds, even though it’s a ironic — they produce strong winds,” Kebbler said. “But for the development and strengthening of the storms, they don’t like strong winds.”
On Thursday, the National Hurricane Center noted that the vast majority of tropical storms and hurricanes — 90% — tend to appear in August, September and early October. So, while the start to the 2022 hurricane season might have seemed calm, with just three named storms so far, there is a strong chance it won’t stay that way over the next six weeks. (Typically, there are only an average of about three named storms by Aug. 3, Kebbler said.)
“You can get very active years with these kind of lulls in them,” said Matthew Rosencrans, the lead seasonal hurricane forecaster at NOAA’s climate prediction center.
And a lull is exactly what South Carolina has been in for the last few years. The last time a hurricane hit the state was Isaias in 2020, and the Category 1 storm produced relatively little damage when it made landfall.
“People have a lot more things to do than just sit around and watch the weather. And so if there’s nothing, if something doesn’t happen for a year or two, then that probably does breed some apathy or indifference,” Kebbler said.
However, Kebbler said it’s unclear whether this year will be like 2020 and 2021, when few storms reached the Carolinas at all.
“Crunch time is coming in here in the next six weeks, eight weeks,” Kebbler said. “Just be ready for storms to develop out there. We’ll have to watch each and every one of them to see the track and intensity.
“Don’t be fooled into thinking that we’re not going to get anything.”