Florida is preparing for an "absolute monster" storm as Hurricane Dorian strengthens on its way to the US mainland.

The National Hurricane Center has said Dorian, which is currently a category 2 storm, is expected to become a potentially catastrophic category 4.

Winds of 130mph (209kph) could slam into the US on Monday somewhere between the Florida Keys and southern Georgia - a 500-mile (805km) stretch that reflects the high degree of uncertainty as to where it will make landfall.

A state of emergency was declared in Florida on Thursday, but no immediate mass evacuations have been ordered while the storm's track is unclear.

Donald Trump said in a video posted on his Twitter account on Friday: "It looked like it was going to be a very small storm, that we all got lucky.


"It missed Puerto Rico, it hit the Virgin Islands, but not as bad as it could have, but it really began to form, and form big, and now its looking like it could be an absolute monster."

The US president has even compared Dorian to Hurricane Andrew, which devastated South Florida in 1992.

University of Miami hurricane researcher Brian McNoldy said: "If it makes landfall as a category 3 or 4 hurricane, that's a big deal.

"A lot of people are going to be affected. A lot of insurance claims."

Image: Shoppers have been stocking up on supplies in Florida ahead of Hurricane Dorian's arrival

People in Florida are said to be feeling helpless amid uncertainty as to whether the storm will make landfall.

Dorian was centred around 260 miles (420km) east of the Bahamas as of Friday morning, with is winds blowing at 105mph (165kphn) as it moved northwest at 12mph (19kph).

The country's government issued a hurricane watch for the northwestern Bahamas overnight.

According to the advisory, a watch is usually issued 48 hours before tropical storm force winds are anticipated.

The storm poses a threat to the islands as its track is expected to run just to the north of Great Abaco and Grand Bahama.

Dorian rolled through the Virgin Islands and Puerto Rico as a Category 1 hurricane on Wednesday.

Image: Hurricane Dorian lashed St Thomas in the US Virgin Islands on Wednesday

The initial blow did not appear to be as bad as expected in Puerto Rico, which is still recovering from the devastation wrought by Hurricane Maria two years ago.

But the tail end of the storm unleashed heavy flooding along the eastern and southern coasts of Puerto Rico.

Cars, homes and gravestones in the coastal town of Humacao became halfway submerged after a river burst its banks.

Dorian caused an island-wide blackout in St Thomas and St John in the US Virgin Islands and scattered outages in St Croix, government spokesman Richard Motta said.

Mr McNoldy said the storm is expected to pick up steam as it pushes out into warm waters with favourable winds, adding: "Starting [Friday], it really has no obstacles left in its way."

Forecasters said coastal areas of the southeast could get 5 to 10 inches (13 to 25cm) of rain, with 15 inches (38cm) in some places, triggering life-threatening flash floods.

Jeff Byard, an associate administrator at the Federal Emergency Management Agency (FEMA), warned that Dorian is likely to "create a lot of havoc with infrastructure, power and roads".

Mr Byard said: "This is going to be a big storm. We're prepared for a big response."

Image: NASA's Terra satellite has captured this image of Dorian heading to Florida

Florida governor Ron DeSantis declared a state of emergency, clearing the way to bring in more fuel and call out the National Guard if necessary.

Georgia's governor followed suit.

Royal Caribbean, Carnival and Norwegian have begun rerouting their cruise ships.

Major airlines began allowing travellers to change their reservations without a fee.

Local governments across Florida's east coast have began distributing sandbags along Florida's east coast, while shoppers have rushed to stock up on food, plywood and other emergency supplies at supermarkets and hardware shops.

Image: Motorists in Winter Springs, Florida, queue to fill up on petrol before the storm hits

Motorists have filled their tanks and petrol cans, with some fuel shortages reported in the Cape Canaveral area.

Josefine Larrauri, a retired translator, went to a Publix supermarket in Miami only to find empty shelves in the water section.

She said: "I feel helpless because the whole coast is threatened.

"What's the use of going all the way to Georgia if it can land there?"

Lauren Harvey in Vero Beach, about 140miles (225km) up the coast from Miami, has scoured the aisles of a nearby supermarket for non-perishable food items that could last her through the storm.

Ms Harvey, who recently moved from the Philadelphia area, said she is not sure what to expect and is preparing to spend her very first hurricane alone.

She said: "I just moved here, I'm so lost.

"I don't know what I'm going to do."