New Orleans - the Crescent City, home of Mardi Gras and the Sugar Bowl, and to meteorologists, one of this country's most vulnerable big cities to a major hurricane strike.

Last week's 12-inch flooding rains from Tropical Storm Isidore refocused attention on the Big Easy as a disaster waiting to happen. The city is surrounded by water, Lake Pontchartrain to the north, the Mississippi River snaking to the south, with marshlands and the Gulf of Mexico not far beyond. The city actually lies in a bowl - most of it is below sea level, by six feet on average, so every drop of water has to be pumped out. Once two inches of rain falls, however, the pumps can only handle half an inch of rain per hour - anything more than that causes flooding.

Though a network of levees and flood walls surrounds the city, even they wouldn't provide enough protection from the storm surge of a Category 4 or 5 hurricane. In that case, evacuations would be necessary to avoid a catastrophic disaster, but those would have to start at least 72 hours ahead of time to accommodate the city's population of about one million - an unrealistic requirement given that the average error in a 72-hour hurricane forecast is more than 200 miles.