Sandy was not quite a 100-year storm, but still one of the worst, emergency management official says

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OCEAN CITY — In 50 years, Hurricane Sandy will be remembered the same way the March 1962 nor’easter is remembered today – a devastating storm. But determining the severity of a storm, whether it’s a considered a hurricane or a nor’easter, requires a thorough review of the wind, waves, tide and water.

A chart in Wallace Hardware measures the water height of every storm that has ravaged Ocean City since the Asbury Avenue store opened more than a century ago. The notch for Hurricane Sandy stands nearly a foot higher than the January 1992 storm, the Halloween storm of 1991, the March 1962 storm and the 1944 hurricane.

While representatives from the National Oceanic and Atmospheric Association study data to determine whether the storm was a hurricane or a powerful northeast storm – an important determination for insurance coverage – Ocean City Emergency Management Coordinator Frank Donato said local officials have determined that the super storm, regardless of whether it is officially categorized as a hurricane when it made landfall, surpassed the benchmark of a 50-year storm, but fell short of a 100-year storm. The classification, he said, is part of the nomenclature of coastal storms.

Clearly Hurricane Sandy flooded the island more than any other in the past century, but Sandy’s impact depends on how it’s measured, according to Donato.

As far as wind speed, Donato said a weather flow set up in a parking lot at 59th Street picked up a wind gust of 70.2 mph at 10:35 p.m. on Monday evening, after the eye of the storm passed.

Donato said the wind picked up considerably that night, hitting a peak between 10 p.m. and midnight.

“The average wind speed during that time was 50 mph,” he said. “That’s pretty impressive and what did the most damage. A lot of the damage to the power lines occurred during that time.”

There were two astronomical high tides during the storm; the second, on Monday night, hit 10.02 feet above mean low water, recorded at the Bayside Center as measured by the U.S. Geological Survey, Donato said.

Mean low water, he said, is how most of the tide charts commonly utilized by fishermen and water sport enthusiasts are configured. It is one of two ways of measuring tide height.

“The tide on Monday night was expected to be about 4 feet, 6 inches,” he said. “It ended up being more than 5 feet, 6 inches higher than that. The tide was more than double what it would have been under normal conditions.”

The mean low water measurement, he said, is based on sea level.

Another scale, the National Geodetic Vertical Datum, was formulated in 1929 and has been used by surveyors and engineers ever since.

Donato said this engineering method is very complicated and better understood by engineers and architects than it is by the rest of the world. It provides a national benchmark, a consistent point of measurement to provide a reliable means of “mapping” and comparing the entire country. It is not based on sea level, because engineers argue that sea level can change from one seaside community to the next.

Using this national starting point, Donato said the tide was a less impressive 8 feet, 5 inches. Ten feet is the 100-year storm mark.

“So based on that, we were a little below,” he said.

“Historically, we have measured storms based on mean low water,” Donato said. “Certainly, some would argue that it’s not the only way to measure. There are many facts to consider. The bottom line is that Sandy would be considered once-in-a-lifetime. It definitely supports the 50-year storm, but not quite the 100-year storm threshold, depending on how you look at it.”

Comparing Sandy to other storms that have hit Ocean City, Donato said, Sandy would be considered the worst.

“If this were a 100-year storm, you have to think about the impact,” he said. “You’re talking another foot and a half, thousands more properties would have been damaged. Imagine, that would have included almost all of the newer homes that had water underneath, but not inside of their homes.

“Either way, a 50-year storm or a 100-year storm, it’s considered a once in a lifetime storm,” he said. “With Sandy, we had some of the worst possible conditions.”

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