Hurricane Isabel—One of Strongest to Hit U.S.?

Willie Drye
Special for National Geographic News
Updated September 17, 2003

Watch a special news report on hurricanes—the science of understanding and predicting these destructive storms, a behind-the-scenes look at Hurricane Andrew, and a review of other memorable hurricanes—at 8 p.m. ET/PT tonight on our U.S. cable television program National Geographic Today.

For the past two weeks, the storm that's now Hurricane Isabel has been thrashing westward across the Atlantic Ocean, stoking itself on the tepid late summer waters and steadily growing into a monster with the power to level a city.

Since September 11, Isabel's strongest winds often exceeded 155 miles per hour (250 kilometers per hour). When hurricanes have winds this strong, meteorologists classify them as Category Five on the Saffir-Simpson Scale, which rates hurricanes according to wind speeds and destructive potential.

Category Five storms pack the energy of multiple atomic bombs. If one of these were to make landfall at full roar, the results would be catastrophic. Houses would be shattered, automobiles would be flung around like autumn leaves, soda straws would pierce oak trees, the sea would rise up higher than telephone poles and it would all be accompanied by an unearthly ear-splitting screech.

Luckily, the watery mechanism that creates and sustains these terrible storms is as quirky and delicate as it is powerful. A slight decrease in water temperature or the presence of powerful winds high in the atmosphere can shut off a hurricane's fuel and tear it apart, quickly sapping much of its power.

By Monday, the National Hurricane Center downgraded Isabel as a Category Four hurricane, with maximum sustained winds of near 140 miles per hour (220 kilometers per hour).

At 2 p.m. Eastern Time today, September 17, the center of Hurricane Isabel was located 350 miles (560 kilometers) south-southeast of Cape Hatteras, North Carolina, and expected to make landfall in the eastern part of the state during the day tomorrow.

Isabel is now a Category Two hurricane, with maximum sustained winds near 105 miles per hour (169 kilometers per hour) and higher gusts extending outwards up to 115 miles (185 kilometers) from the storm's center. Storm surge flooding of seven (2.1 meters) to 11 feet (3.35 meters) above normal tide levels may be expected, while storm total rainfalls of six to ten inches (150 to 250 millimeters) are likely. There is also the threat of isolated tornadoes in association with Isabel.

When Powerful Hurricanes Come Ashore

While powerful hurricanes do sometimes come ashore, it's unusual for a Category Five storm to make landfall in the United States. In fact, it's happened only three times since hurricane record keeping started in 1886. The most recent time was August 24, 1992, when Hurricane Andrew's 170-mile-per-hour (275-kilometer-per-hour) winds changed the face of South Florida.

On August 18, 1969, Hurricane Camille roared off the Gulf of Mexico and slammed into Mississippi with 190-mile-per-hour (300-kilometer-per-hour) winds and a storm surge that buried oceanfront buildings beneath 25 feet (7.6 meters) of seawater.

But the storm that set the standard for sheer power smashed into the Florida Keys on Labor Day Monday of 1935. Unlike Isabel—which achieved its massive power while still far out at sea—this anonymous killer waited until the last minute to intensify into a force of incalculable power. It was a minimal tropical storm when it crossed the Bahamas with 40-mile-per-hour (65-kilometer-per-hour) winds during the night of August 31–September 1.

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