Louisiana at greater risk of hurricanes in record-setting storm season
Texas and Louisiana may have braced for the worst this week as back-to-back hurricanes Marco and Laura barreled toward them, but in this record-setting Atlantic hurricane season, almost every coastal U.S. state east of the Mississippi River should also be on high alert.
All but one of the 18 states bordering the Atlantic Ocean or Gulf of Mexico face a greater risk this year of a hurricane strike, according to the forecast from Colorado State University’s Department of Atmospheric Science, which has issued seasonal hurricane forecasts every year since 1984.
Only New Hampshire’s risk remains unchanged at a 1% chance of a direct hit. Every other state’s risk increased by 33-100%.
In Louisiana, the CSU team predicted the odds of a land-falling hurricane this year at 43%, compared to a historical probability of 30%.
Blame the increased risks on warmer-than-average sea surface temperatures, weaker tropical Atlantic trade winds and a reduced vertical wind shear that would otherwise help to break up tropical storms before they can strengthen.
Those conditions have made 2020 a record-setter. It’s the first year the Atlantic Ocean has seen nine named storms before Augustand 13 before September.
Seven of those storms have made landfall. The most recent was Hurricane Laura, which slammed into Texas and Louisiana this week. This is the first year that more than a half dozen storms have made landfall before September, said Phil Klotzbach, lead forecaster of the Colorado State University meteorologyteam.
Laura is the 12th named storm. Marco, which briefly reached hurricane status before striking the northern Gulf Coast as a tropical storm, was the 13th named storm. Even though Marco fell apart, it still dumped heavy rainfall in Florida’s Panhandle, including 11.8 inches in Apalachicola.
La Niña looms
The hyper-active season is forecast to continue in the weeks ahead as a pattern of cooler-than-normal sea surface temperatures called La Niña continues to develop along the equator in the Pacific Ocean.
“That increases the likelihood of an extremely active Atlantic hurricane season,” said Gerry Bell, a research meteorologist and lead seasonal forecaster for the National Oceanic and Atmospheric Administration.
La Niña also points to an increased risk for land-falling hurricanes along the U.S. coast, Klotzbach said.
No one along the coast of the mainland U.S. is exempt from the threat of a land-falling storm, but more hurricanes strike states along the Gulf than anywhere else on the mainland.
Florida has suffered the most. Of the 296 known hurricanes that struck the U.S. between 1851 and 2019, 118 have hit or sideswiped Florida. That’s nearly twice as many hurricanes as the 65 in Texas, the state with the second-most hurricane impacts. Louisiana and North Carolina are third and fourth.
Of the 60 hurricanes on record that have had a direct impact in Louisiana, 20 have been major hurricanes, with sustained winds at the center of 111 mph or more. The state has 397 miles of coastline.
An immediate threat
Regardless of the odds, the only hurricane that matters most is the one headed in your direction.
Given the dire forecast and the impacts of the coronavirus pandemic, meteorologists, emergency management officials and others worry about how millions of coastal residents will make decisions this year regarding evacuations and sheltering when a hurricane approaches. They say it’s especially important this year to know your risks and plan ahead.
“Every hurricane season I’m concerned so many people live on the coast who have never been through a tropical storm or hurricane,” said Alan Sealls, chief meteorologist at NBC 15 in Mobile, Alabama. “We’ve had huge population growth along the coastline.”
As Laura approached the northern Gulf Coast, forecasters at the National Hurricane Center warned of a potential storm surgeas high as 13 feet. The destructive force of storm surge is the leading reason why barrier islands and low-lying areas are evacuated before a hurricane.
In Louisiana, 72,883 homes are at risk of storm surge from a Category 1 hurricane, according to the Insurance Information Institute. Many more are at risk when a storm grows more intense, with 770,030 homes at risk of storm surge from a Category 4 hurricane, with sustained winds at 130 mph or more.
This year, emergency management officials throughout the country have had to make adjustments to planning to account for the coronavirus complications, Sealls said. “Shelters are going to have lower capacity and that means a lot of people are going to be jammed up about whether they go and what they can do.”
Ultimately, his advice to people is: “If a major hurricane is coming toward you, that’s an immediate threat. COVID is a potential threat.”
“You always have to deal with the immediate threat,” he said. But for families watching the forecasts and weighing the impacts, he said it’s going to be a “awful” tough decision.
People must plan ahead
Especially this year, individuals and families in the path of a hurricane need to be prepared and act early, said Pamela Marie Murray-Tuite, a civil engineering professor at Clemson University in South Carolina who studies hurricane evacuations.
“If you have flexibility and you leave as soon as you know an order is coming, it gets you ahead of the crowd,” she said. This year, as people continue trying to social distance, she said that might be particularly important to help distribute the demand for rest stops and gas.
Jason Senkbeil drives into potential hurricane strike zones to ask people what they’re thinking before the storm, to try to understand how they look at risk and hazards. An associate professor in the geography department at the University of Alabama, he asks people about their perception of a storm’s track and whether they’re more concerned about the wind, the storm surge, or falling trees.
He’s found that often people who have not been ordered to evacuate leave anyway, thinking the storm is coming closer to their home than forecasters at the Hurricane Center predict. But he’s also found people who downplay the risks or wait too late to evacuate.
He encourages people to know ahead of time if they’re in a potential evacuation zone, to know their elevation and talk to neighbors and others about what happened in the neighborhood with previous storms, even while understanding that the impacts from storms could be vastly different.
People looking to make the best decisions if a storm looms this season should have an advance plan for evacuation and sheltering, he said, and pay close attention to the official forecast.
Both he and Sealls raised questions about where people in the path of a hurricane get their information.
Those looking at the plethora of raw forecast data available on their smartphones, said Sealls, wind up making decisions about evacuations and sheltering “based on their perception of the forecast and not necessarily the forecast.”
When Hurricane Michael struck Florida’s Panhandle in October 2018, Senkbeil said many weren’t following the storm closely and were surprised when it suddenly strengthened before landfall.
It became "very obvious" that Michael was intensifying overnight, he said. But many woke up to "a new reality" and thought it was "too late" to leave.