‘Quieter’ hurricane season opens to qualms

“Quieter” tropics don’t mean much when it comes to Lowcountry hurricanes.

That might be the best take-away from forecaster predictions of an “average” or “quieter” storm season in the Atlantic Basin — especially after the rare early arrival of two tropical storms.

Today is the start of the basin’s official June-November season.

There is some new emphasis this go-round: Get ready.

Tropical Storms Alberto and Beryl have already blown up. It’s so rare for two tropical storms to devil the Lowcountry before June that it hasn’t been recorded to happen since 1887, with two May storms that stayed offshore.

“It sends a little shiver up your spine,” Charleston Mayor Joe Riley on Thursday told a regional conference of emergency management groups.

So much for quieter. There seems to be a general uneasiness about this season that’s reflected in remarks like Riley’s “shiver.”

“We’re definitely overdue and it’s years like this it’s more likely to happen,” said climatologist Cary Mock, of the University of South Carolina, who has researched tropical cyclone trends in the region.

Alberto and Beryl are examples of the sort of “pop-up” tropical cyclone that the Lowcountry is more prone to than the dread Cape Verde storms that barrel across the Atlantic.

The most recent hurricane to make landfall here, Gaston in 2004, formed just offshore from a line of thunderstorms that blew off the coast.

Pop-ups might be a trend this year. At least one forecasting company, AccuWeather.com, said indications are for more “homegrown” storms.

They can’t be forecast yet by seasonal computer models, climatologists say.

“The ‘pop-ups’ are unpredictable. We can clearly go above or below ‘average,’ no matter what the basin does,” Mock said.

Whether a tropical cyclone affects the Lowcountry also depends on variable regional climate factors such as the positioning and movements of air pressure systems like the Bermuda High — wheel-like wind circulations that tend to steer storms.

Positioning of the Bermuda High last year played a role in keeping a series of powerful hurricanes out to sea.

This year so far, the high was among the weather factors that lined up favorably to push away Alberto and push in Beryl.

The Bermuda High tends roughly to stay put for periods of time, but even that is tough to predict.

The high “is better described as quasi-stationary. It only takes a brief wiggle and the right synoptic pattern to yield a pop-up tropical cyclone,” said Mark Malsick, S.C. Climate Office severe weather liaison.

As for the basin predictions, Hugo, the 1989 monster that devastated the Lowcountry, developed in a relatively quiet year when only 11 named storms formed.

It was a Cape Verde hurricane. And, its impact on Charleston was more like a Category 2 storm than the Category 4 storm impact it had to the north of the city, said Ron Morales, warning coordination meteorologist with National Weather Service, Charleston, at the Thursday conference.

It doesn’t take a monster to do a number.

Gaston was only a marginal hurricane thought at first to be a tropical storm. It did $20 million in insured damage in South Carolina alone.

If the mild Beryl had blown through this week at high tide, its three-foot storm surge would have brought widespread coastal flooding, Morales said.

The bottom line is, as Malsick noted, “it only takes one landfall to ruin your day.”

Reach Bo Petersen at 937-5744, @bopete on Twitter or Bo Petersen Reporting on Facebook.

Science and environment reporter. Author of Washing Our Hands in the Clouds.