NEW ORLEANS: People boarded up buildings, stocked up on water and braced for torrents of rain and punishing wind from a strengthening Tropical Storm Barry that threatened millions as it churned a path ashore and tested efforts to guard against flooding since Hurricane Katrina devastated New Orleans 14 years ago. Officials predicted Barry would make landfall Saturday morning near Morgan City as the first hurricane of the season, with the edges of the storm already lashing Louisiana with rain and leaving some coastal roads underwater. Though expected to be a weak hurricane, just barely over the 74 mph (119 kph) wind speed threshold, it threatened disastrous flooding across a swath of the Gulf Coast. The storm was expected to inflict the most damage on Louisiana and parts of Mississippi, with wind and rain affecting more than 3 million people. Late Friday night, residents received good news from forecasters: the Mississippi River is expected to crest in New Orleans at about 17.1 feet (5.2 meters) on Monday, not 19 feet (5.8 meters) as had been earlier predicted. The levees protecting the city range from about 20 to 25 feet (6 to 7.5 meters) in height. Governors declared emergencies in both states, 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 abnormally high from heavy spring rains and melting snow upstream. 'My concerns are just hoping it's not going to be another Katrina,' said Donald Wells, a restaurant cook in New Orleans. Authorities told at least 10,000 people in exposed, low-lying areas along the Gulf Coast to leave, but no evacuations were ordered in New Orleans, where officials urged residents to 'shelter in place.' Before they did, people packed stores to stock up on bottled water, food and other essentials. Lifelong New Orleans resident Terrence Williams grabbed supplies at a Costco, saying he has a few simple rules for big storms. 'Stock up on water. Stock up food. Get ready for the storm — ride it out,' he said. Scott Daley, 55, manoeuvred two shopping carts filled with bottled water, gallons of milk and frozen meat at a Walmart in Lake Charles, in southwestern Louisiana. 'I've got five small children at the house. So we're just hunkering down,' he said. Forecasters said slow-moving Barry could unload 10 to 20 inches (25 to 50 centimetres) of rain through Sunday across a swath of Louisiana that includes New Orleans and Baton Rouge, as well as southwestern Mississippi, with pockets in Louisiana getting 25 inches (63 centimetres). 'It's powerful. It's strengthening. And water is going to be a big issue,' National Hurricane Center Director Ken Graham warned. Workers also shored up and raised the levee system in places with beams, sheet metal and other barriers. Rescue crews and about 3,000 National Guard troops were posted around Louisiana with boats, high-water vehicles and helicopters. President Donald Trump declared a federal emergency for Louisiana, authorizing federal agencies to coordinate relief efforts. Scientists say global warming is responsible for more intense and more frequent storms and flooding, but without extensive study, they cannot directly link a single weather event to the changing climate. Tracking forecasts showed the storm moving toward Chicago, swelling the Mississippi River basin with water that must eventually flow south again. Before the worst of the storm, Kaci Douglas and her 15-year-old son, Juan Causey, were among dozens filling sandbags at a fire station in Baton Rouge. She planned to use them to shore up the door of her townhouse. 'I told my son, it's better to be safe than sorry,' she said. In New Orleans, a group of neighbours cleaned out the storm drains on their street. Working together to lift off the heavy metal covers, they discovered that most of the drains were full of dirt, leaves and garbage. All over town, people parked their cars on the city's medians — referred to by locals as 'neutral grounds' — in hopes their vehicles would be safe on the slightly elevated strips. After Katrina was blamed for more than 1,800 deaths, by some estimates, the Army Corps of Engineers began a multibillion-dollar hurricane-protection system that isn't complete. The work included repairs and improvements to some 350 miles (560 kilometers) of levees and more than 70 pumping stations.