The steady march of Hurricane Matthew has left more than 1 million customers in Florida without power, state officials said, as the storm moved north along the US east coast after killing hundreds of people in Haiti.

The updated totals were released on Friday as the powerful storm, now downgraded to a Category 2, headed towards the state of Georgia, still packing wind gusts of up to 100 km per hour. 

A woman in her late 50s suffered a medical emergency and died in her home in central Florida's St. Lucie County, as high winds prevented rescue workers from reaching her, a Florida fire department spokeswoman told AFP news agency.

IN PHOTOS: Scenes of destruction in Haiti after Hurricane Matthew

At Cape Canaveral, strong winds lashed NASA's rocket launch facility, forcing power outages and damaging roofs, the US space agency said.

Rockets, spaceships and crucial equipment for the US space programme and private companies like SpaceX are all stored in the area, which is home to the Kennedy Space Centre.

President Barack Obama urged residents in the path to heed emergency officials' warnings, adding that although there has already been "significant damage", storm surge and flooding are still a major concern.

"People should listen to their local officials," if they urge them to move away from storm surges, Obama said.

"We can always replace property," but we cannot replace lives, he told reporters following a briefing with his top federal emergency and security officials. 

Hurricane Matthew is also threatening US states Georgia and the Carolinas [AFP]

Less damage than expected

Florida Governor Rick Scott also warned that storm waves could reach as high as three metres and cause extensive flooding, and urged people who are still in their homes to get out.

Al Jazeera's Andy Gallacher, reporting from Fort Lauderdale, said the southern coast of Florida had been spared by Matthew's direct hit.

"A lot less damage, a lot less impact that we were expecting perhaps 12 hours ago," our correspondent said.

Still, Hurricane Matthew caused major problems for travelers, with at least 4,500 flights canceled so far between Wednesday and Saturday, according to tracking service FlightAware.

All flights to and from Orlando cancelled on Friday and half of all flights were cancelled in the lead up to Saturday.

As the storm moves north, so do cancellations in Atlanta, Savannah, Charleston and other major cities along the east coast.

Airports in southern Florida began to reopen late on Friday, however, and flights were expected to resume by midday.

Airlines moved planes and crews out of the storm's path and must now fly them back into the region.

Hurricane Matthew left at least 572 people killed in Haiti alone.

 

Analysis: Rob McElwee, Al Jazeera Senior Weather Presenter

Forecasting the track of a hurricane is a skill requiring computer models of the atmosphere. But just as in other predictions, the final detail is never going to be exact.

In the case of a hurricane, the centre is often critical, and may even be the difference between life and death. Because of the inevitable variability of detail, a probability field is the most useful forecast.

During the life of a major hurricane, several eyewall replacement cycles are likely. These are visible from space by the hole in the centre of a hurricane closing and reopening.

While it is happening, an eyewall replacement cycle tends to reduce, temporarily, the very strongest winds. It also spreads the hurricane-force winds further away from the centre. This puts more a greater area at riskof wind damage.

The cause of eyewall replacement cycles is still a subject of investigation, but as each takes many hours, they can be observed. One was underway as Hurricane Matthew scraped past Cape Canaveral in the US.

The original small eye of Matthew was still visible at 1200 GMT, but the much larger surrounding eye, approximately 80km in diameter, brought wind gusts in excess of 100 km/h per hour right on to coastal Florida. Cape Canaveral, fully exposed to the outer eye wall, reported gusts of 155km/h.

The general direction of travel of Matthew is northwest, parallel with the coast. The anti-clockwise spin of the winds is building waves of atleast 5 metres high and driving them into the coast of Florida and Georgia.

The most destructive part of most hurricanes is not the wind but the water. A storm surge of piled up ocean is an unstoppable coastal tsunami. In the case of Hurricane Matthew, the surge may be 3 metres high.

The surge has already started in eastern Florida with shallow beaches inundated even at low tide. At high tide, the barrier island will be at risk from the additional surge with waves on top.

There are occasional breaks in the barrier island itself and these will allow access for surge waters to the inner beaches.

North of Jacksonville, Florida there is no barrier island. The lowcoast of the northeast - Florida, Georgia and South Carolina - is open to storm surge flooding and the surge will coincide with at least one high tide.

Source: Al Jazeera And Agencies