US forecasters said Hurricane Nate is expected to strengthen into a Category 2 hurricane, packing winds of around 100 mph (160 kmph) when it slams into the central Gulf Coast Saturday night.

The storm is gathering strength over the warm waters of the Gulf of Mexico. It's currently a Category 1 hurricane with 90 mph winds steadily increasing. That is the lowest-intensity grade on the Saffir-Simpson hurricane scale, but still capable of causing enormous damage.

It is also moving briskly over the gulf at 26 mph.

New Orleans Mayor Mitch Landrieu on Friday ordered an evacuation of several areas of the city, saying a mandatory curfew would go into effect before Hurricane Nate makes landfall.  

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"I encourage everyone to stay off streets starting tomorrow [Saturday] at 6 p.m. (2300 GMT/UTC) and until we are clear on Sunday, so we can keep you safe," Landrieu said in a tweet.

"We are strongly urging residents to secure outdoor furniture, loose debris and garbage cans, which can turn into projectiles during high wind … As we shared yesterday, none of our preparations will matter if citizens do not do their part."

In 2005, Hurricane Katrina devastated New Orleans, leaving behind a trail of death and destruction, most notably in Louisiana.

The Miami-based US National Hurricane Center (NHC) issued a hurricane warning for parts of Louisiana, Mississippi and Alabama, where multiple shelters were opened for residents who had to be evacuated.  

A state of emergency was also declared for 29 Florida counties.

Powerful winds and storm surge

Some areas of the US were predicted to be hit with a 2.5-meter (8-foot) storm surge.

"The combination of a dangerous storm surge and the tide will cause normally dry areas near the coast to be flooded by rising waters moving inland from the shoreline," the NHC warned.

Louisiana Governor John Bel Edwards warned people in low-lying areas to take heed of cautions. 

Deadly storm

Tropical Storm Nate left 26 people dead and thousands more displaced in Central America. It caused widespread flooding in Nicaragua, Costa Rica and Honduras after pummeling the region on Thursday.

Nate brushed the edge of Mexico's Yucatan Peninsula on Friday night, dumping at least 8 inches (20.3 centimeters) of rain. 

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The storm has gained speed and power as it crosses the Gulf of Mexico, with meteorologists forecasting it will hit the southeastern US between Saturday evening and Sunday morning.  

"The threat of the impact is increasing, so folks along the northern Gulf Coast should be paying attention to this thing," the NHC's Dennis Feltgen said.

bik, aw, ls/jm (AP, Reuters, AFP)