MIAMI: Authorities in Louisiana and elsewhere on the US Gulf Coast issued increasingly dire sounding warnings Saturday as Hurricane Ida, a storm expected to pack powerful 130 mph winds, moved with unexpected speed toward the New Orleans area.

"Ida is expected to be an extremely dangerous major hurricane when it approaches the northern Gulf coast on Sunday," the National Hurricane Center (NHC) said, adding that storm preparations should be "rushed to completion."

Tropical storm-force winds are expected to hit the area Saturday afternoon, with Ida expected to slam into the Louisiana coast as a powerful Category Four hurricane on Sunday evening.

In New Orleans, Mayor LaToya Cantrell warned residents to take Ida with utmost seriousness.

"Time is not on our side," she said in a televised news briefing on Saturday. "It's rapidly growing, it's intensifying."

Southern Louisiana was bracing for massive damage and flooding - with rainfall of up to 20 inches (50 centimeters) predicted in spots - as the fast-intensifying storm roars through the Gulf after pummeling western Cuba.

Officials warned that power outages were a virtual certainty - and might be long-lasting.

"Extended power loss is almost certain," New Orleans homeland security director Collin Arnold told reporters Saturday. "I'm imploring you to take this storm seriously."

As of late Saturday morning, Ida packed maximum sustained winds of 85 mph (135 kph) and was moving on a northwestern track at a rapid 16 mph, the NHC said.

Cantrell earlier urged people within the city's hurricane protection area to hunker down, adding that anyone outside the area planning to leave should "do so immediately."

"We don't want to have people on the road and therefore in greater danger," she said Friday.

Sunday is the 16th anniversary of Katrina, the devastating hurricane that flooded 80 percent of New Orleans, leaving 1,800 people dead and inflicting billions in property damage.

The city has substantially strengthened its protective levee system since then.

Cantrell said that to avoid the chaos that followed Katrina, with thousands of people stranded by floodwaters, the city has protectively chartered 125 coach buses for post-storm evacuations.