NEW ORLEANS — Louisiana residents hunkered down on Saturday morning as Tropical Storm Barry punched its way slowly and ominously toward the coast, causing widespread power failures, more than a dozen emergency rescues and pounding rainfall in some communities.

The major storm, the first to strike the country this season, was proving to be a misshapen brute inching erratically, but inevitably, toward the communities west of New Orleans.

In New Orleans, fears that the storm could dump more water on an already-swollen Mississippi River, overtopping levees and straining the multibillion-dollar flood protection system put in place since Hurricane Katrina struck 14 summers ago, subsided slightly on Saturday. The river was predicted to crest at 17.1 feet by Monday. Though flood stage for the city is at 17 feet, most of the fortresslike levees and flood walls are at least 20 feet high.