By The Guardian (World News) | Created at 2024-09-26 18:05:13 | Updated at 2024-09-30 11:33:51
3 days ago
Life-threatening storm surges as high as 20ft are expected on Florida’s coast when Hurricane Helene makes landfall late Thursday.
The governors of Florida, Georgia, the Carolinas and Virginia have declared emergencies in their states.
In Florida, the huge storm surges from the initial landfall have been prominent in the warnings from officials, who described it as an unusually large storm with a wind field extending 275 miles from its center.
“A catastrophic and deadly storm surge is likely along portions of the Florida Big Bend coast, where inundation could reach as high as 20ft above ground level, along with destructive waves,” the National Weather Service warned on Wednesday evening.
“Preparations to protect life and property should be completed by early Thursday before tropical storm conditions arrive.”
What is a storm surge?
As a hurricane approaches a coast, the churning winds force ocean water up on to land; atmospheric pressure from the storm also helps squeeze the water ashore. The shallower the continental shelf, the higher the threat of a dangerous surge. The waters may take a couple of days to fully subside.
Water is heavy – about 1,700lbs, 770kg, or a cubic yard – and it can move fast in a surge, sweeping people to their deaths, throwing about boats and vehicles and pulverizing structures. Six inches of fast-moving water is enough to knock over an adult, the National Hurricane Center (NHC) says. Surges become even more dangerous as they coincide with high tide.
Hurricane Katrina in 2005 caused storm surges of over 25ft in New Orleans. The NHC says many of the 1,500 people killed lost their lives, directly or indirectly, to the storm surges.
What will Hurricane Helene’s impact be?
A powerful storm surge can cause long-term damage by sweeping away roads, eroding beaches and contaminating land with saltwater, harming wildlife and agriculture.
As well as the “catastrophic” storm surges from Hurricane Helene on Florida’s Gulf coast, it is expected there will be damaging winds, rains and flash floods hundreds of miles inland across much of the south-eastern US.
Early on Thursday, the National Weather Service said the effects of the storm would depend on its track, though widespread power outages, damage to infrastructure, including power lines, blocked roads and damage to structures are all possible.
“Power outages will likely last days, if not weeks, near where it makes landfall,” the NWS said on Thursday.
Driving on roadways and tree branches falling on homes were the two biggest hazards during storms, said the Florida governor Ron DeSantis at a news conference in Tallahassee. “It will likely be dark by the time this storm passes,” DeSantis said. “Do not try to do any work in the dark. You don’t know what hazards are out there. The sun is going to come out. You’re going to have time to take stock of this.”
US airlines had cancelled more than 1,000 flights by midday on Thursday. Airports across affected regions such as Tampa international, Orlando international and Fort Lauderdale international have also put out posts on X warning travelers of potential delays or cancellations.
The North Carolina governor Roy Cooper warned residents in western and central counties to prepare for heavy rain and “potentially catastrophic flooding. Cooper said the mountains also likely will see landslides, river flooding and debris flows. And cities not necessarily in Helene’s direct path, like Charlotte and Asheville, could see flash flooding, he said.
How is the climate crisis a factor?
As greenhouse gases help trap heat in the atmosphere, they are also helping supercharge the oceans with record-breaking temperatures. The heat in the Gulf of Mexico, where many of these storms congregate, has been abnormally high and this extra heat acts as a sort of jet fuel for hurricanes, quickly turning them into major storms.
Researchers have found that since 1970s, the number of storms escalating into category 4 or 5 hurricanes, with winds of at least 131mph, has roughly doubled in the North Atlantic. “If you look back in time, historically, storms intensified at a slower rate than they do now,” said Phil Klotzbach, a researcher at Colorado State University who specializes in hurricane forecasting.
What will the long-term costs be?
The costs of extreme weather linked to the climate crisis keep on rising. In the US last year there were a record number of 28 disasters that each cost at least one billion dollars.
Hurricane Helene will be the fourth hurricane to make landfall in the US this year and the second major hurricane to hit the state of Florida this year. In August, Hurricane Debby, a category 1 storm, brought power outages and flooding to the north-western part of the state.
