'Life-threatening' Hurricane Michael may make landfall in Florida today

Hurricane Michael has intensified as it barrelled towards the Florida coast, becoming a category 3 major storm as the governor of the southern US state warned residents to prepare immediately for a "monstrous" hit.

Michael was now packing winds of 120 miles per hour (195 kilometers per hour) as it aimed for the Florida panhandle, the finger-shaped strip of land on the Gulf of Mexico.

The National Hurricane Center (NHC) said the storm was expected to make landfall on Wednesday afternoon, bringing hurricane force winds, a "life-threatening storm surge" and heavy rainfall.

"Hurricane Michael is a monstrous storm and the forecast keeps getting more dangerous," said Florida Governor Rick Scott, who has activated 2,500 members of the National Guard in response.

"Hurricane Michael poses a deadly threat," Scott said, warning that it could be the "most destructive storm to hit the Florida panhandle in decades." Panama City Beach fire department chief Larry Couch urged residents to evacuate.

"If they decide to stay, there will be a point where we can't get to them," Couch said. "We will shut down operations at a certain point and when we do that, they're on their own.

"Be safe and leave," he said.

President Donald Trump issued an emergency declaration for the state, freeing up federal funds for relief operations and providing the assistance of the Federal Emergency Management Agency (FEMA).

"It is imperative that you heed the directions of your State and Local Officials. Please be prepared, be careful and be SAFE!" Trump tweeted.

State officials also issued disaster declarations in Alabama and Georgia, both of which are also expected to feel the impact from the storm.

As of 5:00 pm Eastern time (2100 GMT), Michael was about 295 miles (470 kilometers) south of Panama City and moving north at 12 miles per hour (19 kph).

The NHC said some areas of the Florida coast could expect storm surge of nine to 13 feet, and as much as a foot of rain.

The heavy rains could cause flash floods, the NHC said, and spawn tornados in northwestern Florida.

Some 120,000 residents were under mandatory evacuation orders in Bay County in the panhandle, a low-lying area of beachfront resorts and retirement communities.

Michael was forecast to have the power to uproot trees, block roads and knock out power for days when it hits Florida. It is expected to weaken as it moves up into the southeastern United States.

The storm is a category three out of five on the Saffir-Simpson hurricane wind scale.

Drivers waited in long lines at gas stations and residents hurried to fill sandbags, while tolls were suspended on some roads to aid movement ahead of the storm's landfall.

"Since 6:00 am it's been backed up. We're just now running out of regular (gasoline)," Danny Hess, an employee at a gas station in Panama City, told local WJHG television.

The Carolinas are still recovering from Hurricane Florence, which left dozens dead and is estimated to have caused billions of dollars in damage last month.

It made landfall on the coast as a Category 1 hurricane on September 14 and drenched some parts of the state with 40 inches of rain.

Last year saw a string of catastrophic storms batter the western Atlantic -- including Irma, Maria and Harvey, which caused a record-equaling $125 billion in damage when it flooded the Houston metropolitan area.

Scientists have long warned that global warming will make storms more destructive, and some say the evidence for this may already be visible.

At their most fearsome, these low-pressure weather fronts pack more power than the energy released by the atomic bomb that levelled Hiroshima.