Water, not wind, will pack meanest punch

Associated Press

WASHINGTON

Forget the wind and fury. Hurricane Irene’s most worrisome weapon is water.

There’s just way too much of it: storm surge pushing seawater ashore and heavy rainfall causing flooding. That’s not unusual with hurricanes, but with Irene there are added factors that are making meteorologists nervous.

This massive, slow-moving hurricane is forecast to soak an already drenched Northeast and may come ashore at a time when tides are unusually high, making storm surge even worse — 4 to 11 feet with waves on top, forecasters say.

“Water is the No. 1 killer,” retired National Hurricane Center Director Max Mayfield said Friday afternoon. “That’s going to cause the greatest loss of life.”

Many deaths can be avoided if people leave the coast and don’t drive into flooded areas, he said.

MIT meteorology professor Kerry Emanuel said the flooding from Irene could be worse than the 1938 New England hurricane that killed 564 people.

“I think everybody is confident, unfortunately, that this is going to be a bad event from freshwater flooding,” he said.

Forecasters predict Irene will dump 6 to 10 inches of rain in a swath from North Carolina to New England with some areas getting as much as 15 inches of rain. That’s partly because the storm is unusually large and is moving fairly slowly — around 15 mph — allowing it to dump more rain over large areas.

“And all of this rain will come in a short period of time, and that could lead to life-threatening flash floods,” National Hurricane Center meteorologist John Cangialosi said.

Much of the area on Irene’s projected track from Baltimore to New England is already soaked from higher than normal rainfall in the past month. Philadelphia has already had about 13 inches this month, which Cangialosi called “extraordinary.”

When a hurricane comes ashore, it brings with it steadily rising seawater, called storm surge. With waves and wind, it pushes inland along rivers, bays and sounds in addition to the beachfront.

National Weather Service storm surge models — using a computer program called SLOSH — show Irene could bring about 4 feet of water into New York City’s Battery Park at the tip of Manhattan, Emanuel said. The forecast has Irene heading east of New York; it could be far worse if Irene hits just west of the city, he said.

In some places, the storm surge projections are higher. Water levels may rise as much as 6 to 11 feet on North Carolina’s Outer Banks, Cangialosi said.