Ida, which was categorised as a tropical depression two days
earlier, was quickly gaining strength as US weather forecasters warned
residents along the northern Gulf of Mexico coast to rush preparations on
Saturday. Ida is expected to bring winds as high as 130 mph (209 kph),
life-threatening storm surge and flooding rain when it slams ashore in
Louisiana on Sunday.

Officials in New Orleans said that there was no time to
organize a mandatory evacuation of the city’s 390,000 residents, a task that
means coordinating with the state and neighbouring locales so that inbound
lanes on highways can be converted to shunt traffic away from the city.

Highways on the northern Gulf Coast saw steady traffic as
people moved to get out of the storm’s way. Trucks pulling saltwater fishing
boats and campers were part of a steady stream of vehicles leaving the coast on
Interstate 65 in south Alabama. Traffic snarls were reported on Interstate 10
heading west out of New Orleans.

New Orleans Mayor LaToya Cantrell called for a voluntary
evacuation on Friday and reiterated at a midday Saturday news conference that the
time to safely leave was growing short. City officials also were preparing to
announce facilities that would be opened to house anyone needing shelter after
the storm. And they warned those who stayed to be prepared for prolonged power
outage in the days to come, with sweltering heat.

Ida was poised to strike Louisiana 16 years to the day after
Hurricane Katrina devastated the Mississippi and Louisiana coasts, causing
levee breaches and catastrophic flooding in New Orleans, which took years to
recover. Ramsey Green, the city’s top infrastructure official stressed that the
levee and drainage systems protecting the city now are much improved.
“This is a very different, protected city than it was 16 years ago,”
Green said Saturday.

“That said, if we see 10 to 20 inches of rain over an
abbreviated period of time, we will see flooding,” he said.

Ida’s potential threats extended well beyond New Orleans.

Meteorologist Steve Bowen, head of global catastrophe
insight at the risk and consulting firm Aon, said the area that was about to
get hit is especially vulnerable, with large swaths of industries that could
cause environmental damages as well as homes that still have tarps instead of
roofs from multiple storms in 2020.

“It’s not just the coastal impact. It’s not just New
Orleans,” Bowen said. “We’re certainly looking at potential losses
well into the billions.”

Hurricane Katrina was a Category 3 storm when it made
landfall southwest of New Orleans, Ida is expected to reach an extremely
dangerous Category 4 hurricane, with top winds of 130 mph (225 kph) before
making landfall likely west of New Orleans late Sunday.

Ida’s storm surge may overtop some coastal levees that
protect parts of New Orleans on the west bank of the Mississippi River, said
Heath Jones, emergency manager of the Army Corps of Engineers’ New Orleans
District. However, he said they are designed to be overtopped and have
protections in place to prevent more damage. There does not appear to be any
danger of storm surge coming over the levees that protect the city’s east bank,
which makes up most of the city, he said.

A hurricane warning was issued for most of the Louisiana
coast from Intracoastal City to the mouth of the Pearl River, including
metropolitan New Orleans. A tropical storm warning was extended to the
Alabama-Florida line. Warnings of dangerous storm surge stretched from
south-central Louisiana to the Alabama state line and Mobile Bay in Alabama was
under a storm surge watch.

President Joe Biden approved a federal emergency declaration
for Louisiana ahead of the storm.

Additionally, the hurricane center said a new tropical
depression formed early Saturday. It was centered 800 miles (1,285 kilometers)
east of the Leeward Islands. It was expected to remain over the open Atlantic
Ocean and posed no hazards to land.