Isaac was packing 80 mph winds, making it a Category 1 hurricane. It came ashore at 7:45 p.m. EDT Tuesday near the mouth of the Mississippi River, driving a wall of water nearly 11 feet high inland and soaking a neck of land that stretches into the Gulf.
The storm stalled for several hours before resuming a slow trek inland, and forecasters said that was in keeping with the its erratic history. The slow motion over land means Isaac could be a major soaker, dumping up to 20 inches of rain in some areas, and every storm is different, said Ken Graham, chief meteorologist at the National, Weather Service office in Slidell, La.
"It's totally up to the storm," he said.
Isaac's winds and sheets of rain whipped New Orleans, where forecasters said the city's skyscrapers could feel gusts up to 100 mph. Ryan Berni, a spokesman for the city of New Orleans, said the storm had caused only some minor street flooding before dawn and felled trees but had left roughly 125,000 customers in the city without power.
In Mississippi, the main highway that runs along the Gulf, U.S. 90, was closed in sections by storm surge flooding. At one spot in Biloxi, a foot of water covered the in-town highway for a couple of blocks and it looked like more was coming in. High tide around 9:30 a.m. was likely to bring up more water.
In Pass Christian, a Mississippi coastal community wiped out by hurricanes Camille and Katrina, Mayor Chipper McDermott was optimistic Isaac would not deal a heavy blow.
"It's not too bad, but the whole coast is going to be a mess," he said early Wednesday.
McDermott stood on the porch of the $6 million municipal complex built after Katrina, with walls of 1-foot-thick concrete to withstand hurricane winds. As he looked out toward the Gulf of Mexico, pieces of a structure that had stood atop the city's fishing pier washed across the parking lot.