Hurricane Florence took a slight turn to the southwest as it charged toward the Carolinas on Wednesday, with forecasters warning that the Category 3 storm might now produce catastrophic flooding and rain in a larger swath of the coast and farther inland than previously predicted.

The eye of the storm was expected to pass between Bermuda and the Bahamas on Wednesday and arrive at the Carolina coast by Friday. Tropical storm-force winds, extending 175 miles from the center, were expected to arrive on land by Thursday morning, giving more than a million people scarce time at that point to evacuate.

Here are the latest developments:

• The major power supplier for North and South Carolina, Duke Energy, said that the storm could knock out power for up to three million customers across the two states and that it could take several weeks to restore electricity. The estimate is based on modeling from previous storms as well as Florence’s projected path. That number would be about 75 percent of the company’s more than 4 million customers in North and South Carolina. “People could be without power for a very long time,” David Fountain, president of Duke Energy North Carolina, said, adding that Duke will monitor the Brunswick nuclear plant and shut it down if necessary.

• The storm was predicted to slow and the eye could stall just offshore, lapping the coast with high waves and dropping more than 20 inches of rain in flood-prone coastal areas.

• The center of the storm was in the Atlantic Ocean about 435 miles from Wilmington, N.C., on Wednesday morning. It was forecast to crawl inland from Friday and into Saturday morning, drenching areas far from the coast as the storm butts against the Appalachian and Smoky Mountains. Follow the hurricane’s path here.

• The storm’s maximum sustained winds had eased slightly to 125 miles an hour, and forecasters said that its strength would fluctuate in the hours ahead. (Here’s a guide on how the different categories of storms are classified.)

• In addition to powerful winds, a huge, “life-threatening storm surge” is highly likely on the low-lying coasts of North and South Carolina, the National Hurricane Center has predicted.

• Once it is ashore, Florence’s drenching rains may cause “catastrophic flash flooding and significant river flooding” over a wide area of the Carolinas and the Mid-Atlantic states, the hurricane center said. Some spots on the coast could receive as much as 40 inches of rain.

Cassandra Campbell, her daughter Ta’laya Campbell, 8, and her grandson B.J. Bethea, 5, stocked up on bottled water and groceries on Wednesday morning in Myrtle Beach, S.C.CreditLuke Sharrett for The New York Times

• President Trump promised that the federal government was “ready for the big one.” In a post on Twitter, Mr. Trump once again boasted about the government’s response last year to Hurricane Maria in Puerto Rico, where 3,000 people died. Read more here.

• The governor of Georgia became the latest to declare a state of emergency ahead of Hurricane Florence, joining Maryland, Virginia and North and South Carolina.