Hurricane Dorian: Who’s at risk?

People living in the Bahamas are being warned to stay in their shelters until Hurricane Dorian has passed.

The slow-moving category five hurricane is the most powerful storm to hit the islands since records began, bringing sustained winds of up to 165mph (270km/h) and the risk of storm surges of up to 23ft (seven metres).

The US states of Florida, Georgia, North and South Carolina have all issued states of emergency as Dorian edges west.

Where has been hit?

On Monday, Dorian continued its slow, 1mph track across Grand Bahama and the Abaco Islands in the north of the Bahamas archipelago, having made landfall on Sunday.

High winds, heavy rain and flooding seawater are reported to have caused major damage to homes and property on the islands.

There is no official word on casualties but the Red Cross fears some 13,000 homes have been catastrophically damaged or destroyed by the storm.

Storm surges could be devastating

The biggest danger to life and property in Grand Bahama could be from storm surges, which are predicted to be as high as 23ft above normal tide levels – with higher destructive waves.

Storm surges are caused when huge volumes of water are pushed by hurricane-force winds. When they meet land, the water surges inshore at levels far exceeding normal tides.

The eastern US states are also bracing for possible storm surges.

Where is it heading?

Meteorologists are watching the track of Dorian, trying to predict how close it will come to the United States coastline. As Dorian batters Grand Bahama, it sits only 120 miles (190km) from West Palm Beach, Florida.

But even if the eye of the storm does not make US landfall, tropical storm and hurricane-strength winds could still blast Florida and Georgia within days.

Evacuations have been ordered in some coastal communities of South Carolina and Georgia.

Florida Governor Ron DeSantis said the strength of the storm could not be underestimated.

“This storm at this magnitude could really cause massive destruction. Do not put your life in jeopardy by staying behind when you have a chance to get out,” he said, urging people to observe evacuation orders when they were issued.

Dorian’s strength

At category five, Dorian is the the second-strongest Atlantic hurricane on record, with some gusts reaching 200mph (321km/h). It is the fifth Atlantic hurricane to reach the highest category in the last four years.

Hurricane Irma in 2017 was also category five and causing widespread damage across the Leeward Islands, Caribbean and Florida keys, damaging roads, buildings, airports and harbours.

Grand Bahama was also hit by category five Hurricane Matthew in 2016 – many residents had yet to fully rebuild their houses before Dorian’s arrival.

How hurricanes happen

Hurricanes

A guide to the world’s deadliest storms

Hurricanes are violent storms that can bring devastation to coastal areas, threatening lives, homes and businesses.

Hurricanes develop from thunderstorms, fuelled by warm, moist air as they cross sub-tropical waters.
Warm air rises into the storm.

Air swirls in to fill the low pressure in the storm, sucking air in and upwards, reinforcing the low pressure.

The storm rotates due to the spin of the earth and energy from the warm ocean increases wind speeds as it builds.

When winds reach 119km/h (74mph), it is known as a hurricane – in the Atlantic and Eastern Pacific – or a typhoon in the Western Pacific.

"Everybody has a plan until they get punched in the face. Well, we’re about to get punched in the face."
Florida Mayor Bob Buckhorn, ahead of Hurricane Irma (2017)

The central eye of calmer weather is surrounded by a wall of rainstorms.
This eyewall has the fastest winds below it and violent currents of air rising through it.

A mound of water piles up below the eye which is unleashed as the storm reaches land.
These storm surges can cause more damage from flooding than the winds.

"Urgent warning about the rapid rise of water on the SW FL coast with the passage of #Irma’s eye. MOVE AWAY FROM THE WATER!"
Tweet from the National Hurricane Center

The size of hurricanes is mainly measured by the Saffir-Simpson scale – other scales are used in Asia Pacific and Australia.

Winds 119-153km/h
Some minor flooding, little structural damage.
Storm surge +1.2m-1.5m

Winds 154-177km/h
Roofs and trees could be damaged.
Storm surge +1.8m-2.4m

Winds 178-208km/h
Houses suffer damage, severe flooding
Storm surge +2.7m-3.7m

Hurricane Sandy (2012) caused $71bn damage in the Caribbean and New York

Winds 209-251km/h
Some roofs destroyed and major structural damage to houses.
Storm surge +4m-5.5m

Hurricane Ike (2008) hit Caribbean islands and Louisiana and was blamed for at least 195 deaths

Winds 252km/h+
Serious damage to buildings, severe flooding further inland.
Storm surge +5.5m

Hurricane Irma (2017) caused devastation in Caribbean islands, leaving thousands homeless

"For everyone thinking they can ride this storm out, I have news for you: that will be one of the biggest mistakes you can make in your life."
Mayor of New Orleans Ray Nagin ahead of Hurricane Gustav, 2008

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