Hurricane Milton has rapidly intensified into a category five storm as it tears its way towards the US Gulf Coast, the US National Hurricane Center (NHC) has said.
Ferocious winds of up to 160mph (250km/h) have been recorded as Milton heads towards Florida, where it is expected to make landfall on Wednesday night or early Thursday morning, the NHC said.
Floridians have been told to prepare for the state's largest evacuation effort for years, with Governor Ron DeSantis warning that time for people to evacuate is running out very quickly.
Warnings over Hurricane Milton come just 10 days after Hurricane Helene - the deadliest mainland storm since Katrina in 2005 - pummelled through the US south-east, killing at least 225 people. Hundreds of others are still missing.
At least 14 of those deaths were in Florida, where 51 of 67 counties are now under emergency warnings as Milton approaches.
Hurricanes are separated into five categories based on their wind speed. Those reaching category three and higher and considered major hurricanes because of their potential for significant loss of life and damage, according to the US's National Weather Service.
Hurricane Milton is expected to weaken on Tuesday as it travels over the Gulf of Mexico, dropping down to a category three hurricane by the time it makes landfall in Florida's Tampa Bay on Wednesday evening or early on Thursday, CBS News, the BBC's US news partner, reported.
Milton is then forecast to continue tracking north-east, cutting across the Florida peninsula as it heads for the Atlantic Ocean.
Ahead of its landfall, torrential rain and flash-flooding can be expected across parts of Florida from Monday, the NHC warned.
It added that life-threatening storm surges and damaging winds along portions of Florida's west coast were possible from late Tuesday or early Wednesday.
Rainfall totals could reach localised highs of 15in (38cm), and coastal areas could see storm surges of of 5-10ft (1.5-3.5m).
Florida Governor Ron DeSantis warned residents in the storm's path, specifically in areas that have potential for storm surge, to evacuate as soon as possible.
"Time is going to start running out very, very soon," he said.
Counties would begin issuing evacuation orders throughout the day on Monday, and tolls would be suspended on roads in western and central Florida, he said.
DeSantis also warned Floridians it is possible the storm may remain a hurricane throughout its time in the state.
"It's going to remain a hurricane at some level all the way through exiting the east coast of Florida," he said.
Speaking in an earlier briefing, DeSantis said he could not foresee "any scenario where we don't have major impacts".
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Many evacuations are expected in Pinellas County, where at least a dozen people were killed by Helene.
Tampa International Airport announced it would be suspending flight operations from Tuesday because of the storm.
Where and when Milton is expected to hit
The approach of the new hurricane comes as the US government warns that clean-up efforts could take years after Hurricane Helene.
Hundreds of roads in affected areas remain closed, hampering efforts to send aid to hard-hit communities.
It made landfall in late September as a category four hurricane - damaging structures, causing flash flooding and knocking out power to millions of homes.
As well as in Florida, deaths were recorded in Georgia, South Carolina, Tennessee and Virginia - and the worst-hit state, North Carolina.
President Joe Biden has ordered another 500 soldiers to be deployed to North Carolina. The troops - who now number 1,500 in all - will work with thousands of government relief workers and National Guard.
Biden has so far approved nearly $140m (£107m) in federal assistance. The use of the money has become the subject of false claims by Donald Trump, the Republican candidate for next month's presidential election, who said relief money had been spent on migrants.
Trump has been accused of "dangerous" misinformation by the head of the US disaster relief agency.
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