Three Systems Converged Into Mother of All Storms

BOSTON —  It was a weather phenomenon that develops maybe two or three times every century. Three systems, including the remnants of a hurricane, were converging hundreds of miles off New England. Together, they contained the ingredients to produce a serious storm. The only question was whether the timing would be right.

As National Weather Service meteorologist Bob Case tracked the conditions from his office at Boston’s Logan International Airport, his adrenaline was racing as it became clear that not only would the timing be right, but that the systems were combining in such a way that would produce one of the worst cyclones of the 20th century.

“It was a fantastic weather phenomenon,” he said, recalling how the storm took shape in late October 1991, as a deceptive calm embraced much of New England with sunny skies. Before long, the storm exploded with 100-mph winds whipping up 10-story waves that imperiled ships and caused hundreds of millions of dollars in damage.

The sheer magnitude of the five-day storm, the surge of anxiety that fueled the forecasters who tracked it and the horror it rained on New England fishermen and others is relived in a new movie opening this week, “The Perfect Storm.”

The movie focuses on the doomed commercial fishing boat Andrea Gail and its six-member crew.

Aiming to further understanding of its mission of overseeing marine safety by capitalizing on the publicity surrounding the movie, the National Oceanic and Atmospheric Administration assembled Case and several of its weather experts to describe the meteorological recipe that resulted in the “perfect storm,” a term coined by Case.

Although the storm never hit land in the United States, it spun off hurricane-force winds, consumed beaches, tormented coastal residents and reduced sea walls, boardwalks and piers to rubble over a wide swath of the East Coast. The storm blew out windows and flooded former President Bush’s home in Kennebunkport, Maine. It caused waves as high as 30 feet on beaches from North Carolina to Nova Scotia, and high tides crested as much as 7 feet above normal.

The experts said that a virtually unprecedented set of circumstances made the storm possible. A cold front had passed through New England, even as a huge high-pressure system had built up over southeastern Canada. When a low-pressure system moved off the southeastern coast of Nova Scotia, it intensified into a storm.

Making matters worse, the system merged with the remnants of a hurricane, which was like “throwing gasoline on a fire,” Case said.

“There is almost a feeling of excitement as you watch that if you are a meteorologist,” Case said. “A lot of meteorologists, because of their love of weather and nature, find nothing more exciting than an afternoon thundershower.”

The storm moved back toward the East Coast after it formed, an unusual event that complicated the work of forecasters. When they issued warnings about the storm, many coastal residents were not alarmed; not only were they enjoying good weather, but the weather also was fine to the south and west, where storms usually originate.

“Not too many people could fathom--or believe--100-foot waves and hurricane-force winds, 70 to 80 miles-per-hour plus, in a storm that was heading from east to west,” Case said.