Just two days before Hurricane Milton is expected to make landfall in Florida, it rapidly strengthened into a category 5 hurricane on Monday morning, prompting evacuation orders along parts of Florida’s west coast.
For the second time in just two weeks, Florida residents are being warned of life-threatening storm surges hitting the state’s west coast, beginning Tuesday night or early Wednesday.
Storm surge and hurricane watches are currently in effect for portions of the west coast of the Florida peninsula. The National Weather Service said on Monday that in some areas near the coast, including Tampa Bay, the water could reach up to 12ft above ground level.
Mandatory evacuation orders have already been issued in several counties along Florida’s west coast, including Charlotte, Hillsborough and Manatee counties, with more expected to be issued later on Monday.
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 water may take a couple of days to fully subside.
Water is heavy – about 1,700lb, or 770kg, to a cubic yard (0.76 cubic meters) – 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 on the Mississippi coastline. The NHC says many of the 1,500 people killed lost their lives, directly or indirectly, due to the storm surges.
What will Hurricane Milton’s impact be?
Storm surge is often the greatest threat to life and property from a hurricane, according to the National Weather Service, which added that in the past, large death tolls from major hurricanes have often resulted from the rise of the ocean.
The National Weather Service is expecting life-threatening storm surges along Florida’s Gulf coast this week, with some areas predicted to receive a storm surge of as much as 8 to 12ft above ground level.
On Monday, officials in Sarasota county, Florida, issued evacuation orders and said that the predicted storm surge there from Milton is double the amount from Hurricane Helene.
Experts in Sarasota predict a 10-12 ft storm surge for the area, which they say is not survivable on the barrier islands.
According to the National Oceanic and Atmospheric Administration (Noaa), hurricane storm surges can cause extensive damage, and can “severely erode beaches and coastal highways” as well as take out boats and buildings.
“As the waters move inland, rivers and lakes may be affected, and add to the rising flood levels” the administration said.
In 2022, Hurricane Ian produced catastrophic storm surge along the southwest and northeast coasts of Florida. In some areas, the storm surge was up to 18ft.
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 develop, 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 (210km/h), 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 $1bn.
In the aftermath of Hurricane Helene one estimate, by private forecaster AccuWeather, said the damages could be between $225bn to $250bn.