If a hypothetical clone of Hurricane Matthew were to hit Long Island’s South Shore as a Category 3 storm, the effects would be “devastating,” flooding homes and businesses along the coast and potentially overwashing barrier islands, experts said.

While specific impacts are dependent on any number of variables, “Fire Island and other barrier islands would be extremely vulnerable to complete inundation,” said Meghan McPherson, an adjunct in Adelphi University’s emergency management graduate programs and the school’s assistant director of its Center for Health Innovation.

If sections of the South Shore were confronted with the 6- to 9-foot above-ground-level flooding that threatened the coast from northeast Florida to southeast South Carolina, “the inundation and damage would be severe to roads, bridges, homes, businesses, and other critical infrastructure,” she said.

Specific impacts would depend on a wide array of elements, such as meteorological factors, the storm’s direction and exactly where it hit, she said.

Still, residents can imagine what it would be like to have 9 feet of water rise up on normally dry land, she said, with wave activity, even, on top of that. Especially as “the topography of the Island on the South Shore is quite low and porous.”

Without the benefit of land that would slow down and somewhat weaken a storm heading directly to the Island, “We are, in essence, the storm speed bump for Connecticut,” McPherson said.

What’s more, if such a hypothetical storm were approaching at the slow 10 to 12 mph speed of Matthew, water would be gradually piling up along some shoreline communities over a couple of days’ worth of high tide cycles, said Gary Conte, warning coordination meteorologist with the National Weather Service’s Upton office.

As for how such a storm would stack up to superstorm Sandy, McPherson said she avoided such storm comparisons, as “each is unique.”

With Sandy, its storm surge, large size and location were the big problems, according to an Associated Press Q&A, and the superstorm was a combination of three different types of storm systems so it isn’t a good comparison.

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Still, Sandy did bring above-ground-level inundation of about 4.3 to 5.6 feet along Nassau’s Atlantic shores, according to the National Weather Service.

The last direct hit from a major hurricane was from 1938’s Long Island Express, which, making landfall near Bellport, took area residents by surprise.

As a Category 3, it can be seen as “a close analog” to Matthew, said Brian Colle, professor in Stony Brook University’s School of Marine and Atmospheric Sciences.

The Express brought “devastating flooding” to the East End, he said, and created the Shinnecock Inlet. It also wiped out most homes on the Dune Road barrier island, destroying boats and pushing cars and debris three miles inland.