Technology & Science

Everything you need to know about Hurricane Irma

Hurricane Irma — a powerful Category 5 storm that has already torn through a string of Caribbean islands — is heading toward Florida. Here's what you need to know.

Irma is the most powerful Atlantic hurricane on record

Hurricane Irma continued on a west-northwest track Thursday evening, Sept. 7, 2017, with Hurricane Jose close behind. The U.S. National Weather Service upgraded Jose to Category 3. (NOAA National Weather Service)

Hurricane Irma — a powerful Category 5 storm that has already torn through a string of Caribbean islands — is heading toward Florida. Here's what you need to know.

Florida braces for Hurricane Irma

With the storm barrelling toward Florida for a potentially catastrophic blow this weekend, normally quick trips turned into daylong journeys on crowded highways amid a constant search for gasoline and lodging. Airline seats out of Florida were in short supply as well.

People in their vehicles wait in queue to get sandbags at Kissimmee, Fla. (Gregg Newton/Reuters)

Florida evacuation orders in effect

Forecasters and state officials believe Hurricane Irma could be as damaging in terms of economic impact as Andrew in 1992, which for nearly 13 years was considered the costliest U.S. hurricane.

Approximately 5.6 million people in South Florida were under mandatory evacuation orders Thursday, and Gov. Rick Scott urged people in the state to heed that call immediately, but to be patient as so many made the trek north and inland.


Hurricane leaves trail of death and destruction

Hurricane Irma tore through the Turks and Caicos Thursday evening with sustained winds of 280 km/h, the National Hurricane Center said. Irma was moving near the north coast of Cuba and central Bahamas Friday night and into Saturday

Earlier in the day, French, British and Dutch rescuers rushed aid to the Caribbean islands devastated by the hurricane, which left at least 22 dead and thousands homeless.

A man walks among debris as Hurricane Irma moves off the northern coast of the Dominican Republic. (Ricardo Rojas/Reuters)

Why even a record-breaking hurricane can't hit Category 6

A member of the Emergency Operations Committee (COE) monitors the trajectory of Hurricane Irma in Santo Domingo, Dominican Republic. (Ricardo Rojas/Reuters)

The strength of hurricanes is measured by the Saffir-Simpson wind scale, which ranges from Category 1 to Category 5 with winds of 252 km/h or higher. Why isn't there a Category 6? 

"Because once you say catastrophic and there's near complete damage, why do you need a 6?" Dennis Feltgen, a spokesperson for the National Hurricane Center, told CBC News.

How did Irma get so powerful? 

The perfect combination of factors led to Irma becoming a Category 5 hurricane. (NASA/NOAA GOES Project via AP)

High sea-surface temperatures, minimal variation in wind speed and direction as well as moist air combined to create this mega-storm, said Ian Folkins, a researcher with the department of physics and atmospheric science at Dalhousie University in Halifax.

Water evaporates from the surface and rises, leaving an area of lower pressure underneath. The surrounding air gets drawn in to take the place of the rising air, and certain wind conditions can cause that air to rotate.

"Paradoxically," said Folkins, "what you need in the initial stages is weak winds."

Canadian airlines sent planes to get passengers out of Hurricane Irma's path

WestJet, Air Canada and Air Transat have all announced that they were sending planes to the Dominican Republic and Turks and Caicos to get travellers out of the path of Irma.

But some Canadians in the path of Hurricane Irma were forced to hunker down and ride out the storm. A group of Albertans studying in Puerto Rico were staying put in their dorm after being unable to secure any departing flights back home. 

Irma from space

NASA has many eyes on Irma, particularly in space. 

Here, the space agency provides animation from its GOES (Geostationary Operational Environmental Satellite) East satellite, which shows imagery from Sept. 3 to Sept. 7 ending at 8:45 a.m. ET.

And a view of Irma's eye over four days, as seen by the GOES16 Advanced Baseline Imager.

With files from The Associated Press