Sound buoys track Sandy's every wind-whipped move

Hurricane Sandy's sweep through Long Island Sound was monitored by a network of data collection buoys that are part of the Long Island Sound Integrated Coastal Observing System, a project of the University of Connecticut's Marine Sciences Department.

James O'Donnell, the marine sciences and physics professor at UConn's Avery Point campus in Groton, has been overseeing the network for the past 10 years. The buoys recorded the first signs of the storm when it measured wind gusts approaching 50 mph and wave heights exceeding 7 feet Monday morning. The buoys that recorded those data are at Ledge Light, in the mouth of the Thames River, and in Central Long Island Sound, south of Madison and Guilford. Waves and average winds are typically highest in the central Sound, where the estuary is widest and deepest, he said.

By 1:30 p.m., the central Sound buoy clocked gusts of 54 mph and an average wind speed of about 40 mph. Average wind speeds at Ledge Light were about 31 mph at about the same time.

Also measuring the storm's impact is a tide gauge maintained by the National Oceanic and Atmospheric Administration at State Pier in New London. It recorded high tide at 9:30 a.m. was 3 feet higher than the level predicted. By early evening, just after low tide, the gauge showed water levels were nearly 7 feet above the mean low water level.

The LISICOS network also includes buoys in the western Sound, where the storm surge and coastal flooding are expected to be the most severe. The western Sound is most vulnerable to coastal flooding, O'Donnell said, because winds are pushing the storm surge to the west, and the opening at the East River is too narrow to handle the excess water.

The central and eastern sections also face coastal flooding from this storm due to the effect of winds over the Atlantic Ocean pushing water into the eastern sound. O'Donnell said he expects the storm will do more damage than Tropical Storm Irene last year.

Flooding risk along the shoreline was expected to be highest at high tide at 10 p.m. Monday and 10 a.m. today in New London.

James Edson, also a professor of marine sciences at Avery Point, noted that the timing and duration of Hurricane Sandy's arrival are the main reason for its significant impacts. The high tides are higher than normal due to the full moon, bringing severe storm surges at high tide as the storm passes through.

"Normally," he said in an email message, "we would have much less to fear from a Category 1 storm making landfall in New Jersey as the damage would be very localized."

This storm, however, overcame the usual weakening effects of moving over cooler ocean waters because it drew in energy from a larger wind flow, he said.

"In many ways," he said, "it is more of a very strong and very large extra-tropical cyclone. It did feed off the ocean when it was moving along the Gulf Stream to our south, but it has maintained and even increased in strength due to the interaction with the larger scale flow."

For the Connecticut coastline, the storm is bringing strong counterclockwise winds from the east, maximizing the waves and setting up strong surge.

"As such, damage from these effects is a given," he said.

Because Tropical Storm Irene and the October snowstorm last year took down many weak trees and limbs, followed by extensive tree trimming by utility companies, damage should be reduced from the strong and sustained winds of Hurricane Sandy, Edson noted.

"Also, this time of year is working for us as the trees are bare (or quickly becoming bare)," he said. "This reduces the wind forcing on the trees and limbs."

j.benson@theday.com

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