NEW ORLEANS : Carrying “off the chart” amounts of moisture, sprawling Tropical Storm Barry crawled slowly toward shore on Saturday, knocking out power on the Gulf Coast and threatening millions with heavy rains that could last for days in a test of flood-prevention efforts implemented after Hurricane Katrina devastated New Orleans 14 years ago.

As natives and tourists in the Big Easy, Baton Rouge and other heavily populated areas in the storm’s path hunkered down or wandered through quiet, emptied streets waiting for the worst, the Coast rescued more than a dozen people from the flooded remote island of Isle de Jean Charles. Water on the island had risen so high that some residents were clinging to rooftops by the time help arrived.

Video showed water overtopping a levee in Plaquemines Parish, a finger of land extending deep into the Gulf of Mexico, downstream from New Orleans. Officials were still confident that New Orleans’ levees would hold firm. Most of the levees range from about 20 to 25 feet (6 to 7.5 meters) in height.

 

Officials predicted Barry would make landfall as this year’s first hurricane in the morning near Morgan City, west of New Orleans. The small town had an overnight curfew that expired Saturday morning, after on-and-off rain and power outages. People used cellphones to see in the dark, and opened doors and windows to let the warm, sticky tropical air circulate.

 

More than 45,000 people in southern Louisiana had lost power, and some roads were underwater as the edges of the storm lashed southern Louisiana and coastal Mississippi and Alabama with rain.

 

Though expected to be a weak hurricane — just barely over the 74 mph (119 kph) wind speed threshold — Barry threatened disastrous flooding across a swath of the Gulf Coast. By Saturday morning, the storm system had gathered a “big slough of moisture,” meaning “a lot of rain is on the way,” said National Hurricane Center Director Ken Graham.

 

During a storm update through Facebook Live, Graham pointed to a computer screen showing a huge, swirling mess of airborne water. “That is just an amazing amount of moisture,” he said. “That is off the chart.”

 

On the remote Isle de Jean Charles, about 45 miles (72 kilometers) south of New Orleans, Coast Guard rescuers used helicopters to pluck some residents from rooftops and loaded others into boats from flooded homes, Petty Officer Lexie Preston said.

 

Barry was moving so slowly, it was likely that heavy rain would continue throughout the weekend across Louisiana, Graham said. There were predictions of 10 to 20 inches (25 to 50 centimeters) of rain through Sunday across a swath of Louisiana that includes New Orleans and Baton Rouge with some parts of the state possible getting 25 inches (63 centimeters). Looking ahead, tracking forecasts showed the storm moving toward Chicago, swelling the Mississippi River basin with water that must eventually flow south again.

 

Water was flowing over a levee in Point Celeste in Plaquemines Parish, Lt. Gov. Billy Nungesser said. He said crews were working to contain the water.

 

Governors declared emergencies in Louisiana and Mississippi, and authorities took unprecedented precautions in closing floodgates and raising the barriers around New Orleans. Gov. John Bel Edwards said it was the first time all floodgates were sealed in the New Orleans-area Hurricane Risk Reduction System since Katrina. Still, he said he didn’t expect the Mississippi River to spill over the levees despite water levels already running high from spring rains and melting snow upstream.