Millions at risk from massive storm
A dangerous hurricane is about to make landfall in the United States, with colossal rainfall and winds expected to exceed 120km/h.
The Category 1 storm is expected to hit Louisiana, in the nation's south, by Saturday in what the National Hurricane Centre has described as a "life-threatening situation".
Streets in New Orleans have already turned into lakes, with residents wading through shin-deep waters on the streets.
In Grand Isle, the mayor and town council have ordered everyone to evacuate. "We are expecting a rainfall total that can range from six inches (150mm) to 10 inches (250mm)," they said in a statement. "We will be experiencing unusual high tides that will range more than three feet (almost a metre) above ground."
Thousands of Louisianans broke out sandbags or fled to higher ground overnight as the storm threatened to blow ashore, potentially posing a severe test of New Orleans' improved post-Katrina flood defences.
But it is expected to bring more than half a metre of rain in potentially ruinous downpours that could go on for hours as the storm passes through the metropolitan area of nearly 1.3 million people and pushes slowly inland.
Louisiana Governor John Bel Edwards, who declared a state of emergency earlier in the week as the storm brewed in the Gulf of Mexico, warned the storm's blow could form a dangerous combination with the already-high Mississippi River, which has been swelled by heavy rain and snowmelt upriver this spring.
"There are three ways that Louisiana can flood: storm surge, high rivers and rain," Mr Edwards said. "We're going to have all three."
He said authorities did not expect the Mississippi River to spill over its levees - something that has never happened in New Orleans' modern history - but cautioned that a change in the storm's direction or intensity could alter that.
Southeast of New Orleans, authorities handed out sandbags and people piled into cars with their pets and began clearing out. Plaquemines Parish, at Louisiana's low-lying southeastern tip, ordered the mandatory evacuation of as many as 10,000 people, and by midafternoon the area was largely empty. Justice of the Peace David McGaha waited with his mother, his wife and their 15-year-old son and 11-year-old daughter for a ferry so they could evacuate to his mother's house in Alabama.
"If the river wasn't so high, we'd probably stay. You have to worry about the water that'll be pushing against those levees," he said. "They made a lot of improvements to the levee, but they haven't completed all the projects."
The National Hurricane Centre said as much as 500mm of rain could fall in parts of eastern Louisiana, including Baton Rouge. The New Orleans area could get 250mm to 380mm through Sunday, forecasters said.
Meteorologist Benjamin Schott said the chief concern was not the wind: "Rainfall and flooding is going to be the No. 1 threat with this storm."
New Orleans Mayor LaToya Cantrell said the pumping system that drained the city's streets was working as designed but Barry could dump water faster than the pumps can move it.
"We cannot pump our way out of the water levels … that are expected to hit the city of New Orleans," she warned.
However, the city did not plan to order evacuations because Barry was so close and it was not expected to grow into a major hurricane. Officials instead advised people to keep at least three days of supplies on hand and their neighbourhood storm drains clear so water can move quickly.
Hurricane Katrina caused catastrophic flooding in New Orleans in 2005 and was blamed for more than 1800 deaths in Louisiana and other states by some estimates.
In its aftermath, the Army Corps of Engineers began a multibillion-dollar hurricane-protection system that isn't complete. The work included repairs and improvements to some 560 kilometres of levees and more than 70 pump stations that are used to remove floodwaters.
The National Weather Service said it expected the Mississippi to rise to 5.8 metres by Saturday morning at a key gauge in the New Orleans area, which is protected by levees six to 7.6 metres high.