Forecasters warned residents of the danger of life-threatening floods and storm surges as Hurricane Francine hit Louisiana on Wednesday.

The weather system was partly strengthened before it made landfall by warm water in the Gulf of Mexico as residents scrambled to protect properties and hoard emergency supplies.

What we know about the storm

National Hurricane Center (NHC) said the Category 2 storm arrived over land at Terrebonne Parish on the southern edge of Louisiana at 5 p.m. local time (2200 GMT/UTC).

The center added that Francine brought sustained winds of 100 miles (155 kilometers) per hour and could yield 10 feet (just over 3 meters) of storm surge and 12 inches (about 30 centimeters) of rain in some parts of the southern state.

"Heavy rains and hurricane-force winds are spreading inland across southern Louisiana," the agency said, urging people to stay inside and away from windows.

"Conditions are going to go downhill really rapidly over the next couple of hours," said Jamie Rhome, the hurricane center's deputy director, just before landfall. "It's not going to be a good night to be driving on the roads, especially when the sun goes down."

Two hours later the storm was downgraded to Category 1, and later still to a tropical storm. 

"Life-threatening storm surge, hurricane-force winds and heavy rains continue to affect southern Louisiana," the NHC said.

The National Weather Service's New Orleans office issued a flash flood emergency for the city and nearby districts. New Orleans Mayor LaToya Cantrell urged residents to shelter in place.

How prepared was the state?

Louisiana's Republican Governor Jeff Landry declared a state of emergency and requested a federal emergency declaration from President Joe Biden, who swiftly gave it.

"This federal assistance will be pivotal to save lives and property," said Landry on X, the platform formerly known as Twitter. "As Hurricane Francine approaches Louisiana, I appreciate President Biden quickly approving this request."

The Louisiana National Guard said on X that its soldiers were fuelling up vehicles in preparation for the storm, having already mobilized helicopters, boats and supplies for evacuations and search and rescue.

Francine is expected to quickly weaken as it moves inland over Louisiana and neighboring Mississippi, the NHC said.

The low-lying state at the mouth of the Mississippi River was hit by one of the most devastating hurricanes in US history in late August 2005. Hurricane Katrina killed more than 1,300 people as it slammed into the populous city of New Orleans, overwhelming the city's levee system and causing devastating flooding.

Scientists say climate change is likely to play a role in the fast intensification of storms that feed on the energy of increasingly warm seas.

rc/rm (AFP, AP, Reuters)