Hurricane Ida, a Category 4 Storm, Begins to Lash Louisiana Coast

NEW ORLEANS — Hurricane Ida stoked fear and dread in Louisiana on Sunday as the storm grew into one of the most powerful systems to assault the region since Hurricane Katrina.

Residents were forced to flee or hunker down as Ida quickly intensified overnight into a Category 4 storm, with New Orleans in its projected path.

At 10 a.m. Central time on Sunday, the National Hurricane Center warned that life-threatening storm surge and hurricane-force winds had reached the coast of southeastern Louisiana. Widespread power outages were reported.

The eye of the storm was expected to make landfall “in the next few hours,” the center said.

The storm’s maximum sustained winds on Sunday morning were 150 miles an hour, the hurricane center said. A storm becomes a Category 5 at 157 miles an hour.

The trajectory and strength of Ida will present a high-stakes test of the 350 miles of levees, flood walls, pumps and gates that were built up around New Orleans as added storm protection after Katrina in 2005.

Ida has also raised concerns about the city’s hospitals, which were overwhelmed by water and patients during Katrina and are already strained by the resurgence of the coronavirus pandemic.

Sunday is the 16th anniversary of Katrina’s landfall, and Ida’s path was stirring painful reminders of the death and devastation that the 2005 storm wrought, leaving psychological scars that still run deep in the city. The storm killed 1,833 people, inflicted more than $100 billion in damage, and submerged large stretches of New Orleans, leading to scenes of suffering that horrified the nation.

“It’s definitely triggering to even have to think about this,” said Victor Pizarro, a health advocate and a resident of New Orleans who planned to ride out the storm with his husband in the Gentilly Terrace neighborhood. “It’s exhausting to be a New Orleanian and a Louisianian at this point.”

In the wake of Hurricane Katrina, more than $14 billion was spent reconstructing the area’s levee system. The levees, including those that failed during Katrina, were armored with concrete, among other measures.

Though the city rebuilt to defend against a “100-year-storm,” or a storm that has a 1 percent chance of happening every year, local and state officials have said that 100-year-protection isn’t enough at a time when weather events like hurricanes are intensifying and sea levels are on the rise.

Gov. John Bel Edwards of Louisiana described Ida’s potential impact as historical. “We can sum it up by saying this will be one of the strongest hurricanes to hit anywhere in Louisiana since at least the 1850s,” he said on Saturday.

Ida, the first major storm to strike the Gulf Coast during the 2021 hurricane season, strengthened quickly in large part because the water in the Gulf is very warm, and warmer water provides more energy to the storm. The Gulf is normally warm in late summer, but research over the past decade suggests that climate change also plays a role.

Studies have found that the oceans generally are warming as a result of human-caused emissions of greenhouse gases, making the rapid intensification of hurricanes occur more frequently. In Ida’s case, the storm strengthened to a Category 4 only an hour after it first reached Category 3.

The storm threatens a state already imperiled by a different kind of disaster, as hospitals have been inundated by a surge in coronavirus cases. Daily deaths from Covid-19 reached their highest levels in Louisiana last week, forcing stretched hospitals to modify the intense preparations they would normally make ahead of an expected hurricane strike.

The governor said officials had asked hospitals to check generators and stockpile more water, oxygen and personal protective supplies than usual for a storm. The implications of a strike from a Category 4 hurricane while hospitals were full were “beyond what our normal plans are,” he added.

The decision to stay or go was made for some area residents on Friday when New Orleans city officials issued mandatory evacuations for residents living outside the levee system, echoing similar mandates for neighboring parishes. For those inside the levees, evacuations were voluntary.

The Rev. Willie L. Calhoun, Jr., who lives in the Lower Ninth Ward, a New Orleans neighborhood that was ravaged by Katrina, had hoped to take part in a 16th anniversary commemoration Sunday, with a high school marching band and a theme, he said, of “healing, unifying and strengthening our communities.” Instead, on Saturday afternoon, he was in his Lincoln Continental on the verge of getting out of town.

Sheri Fink,Henry Fountain, Tariro Mzezewa and Katy Reckdahl contributed reporting.

Hurricane Ida’s expected landfall Sunday threatened to bring dangerous wind, storm surge and rain to the Gulf Coast exactly 16 years after the arrival of Hurricane Katrina, one of the most costly natural disasters in American history, which left more than 1,800 dead and did more than $100 billion in damage.

The overall impact of storm surge from Ida is predicted to be somewhat less severe than that from Katrina. The 2005 storm was blowing at Category 5 strength in the Gulf of Mexico before weakening as it approached landfall, so it generated enormous storm surge, reaching more than 20 feet in parts of the Mississippi coast. Current projections put the potential storm surge of Ida at 12 to 16 feet in the worst areas.

“Fifteen-foot sure can do a lot of damage,” said Barry Keim, a professor at Louisiana State University and Louisiana State Climatologist. “But it’s going to be nothing in comparison with Katrina’s surge.”

Improvements to the levee system following Katrina have made the New Orleans metro area better prepared for storm surge. But the areas that are likely to receive the most severe surge from Ida may be less equipped to handle it than the area that was hit by Katrina, said Dr. Keim.

Ida is expected to make landfall to the west of where Katrina struck, bringing the most severe storm surge to the Louisiana coast west of the Mississippi River rather than east of the river, as Katrina did.

“We are testing a different part of the flood protection in and around southeast Louisiana than we did in Katrina,” Dr. Keim said. “Some of the weak links in this area maybe haven’t been quite as exposed.”

While the impacts of Ida’s storm surge are expected to be less severe than Katrina’s, Ida’s winds and rain are predicted to exceed those that pummeled the Gulf Coast in 2005. Ida is expected to make landfall on the Gulf Coast as a Category 4 storm with sustained winds around 150 miles an hour; Katrina came ashore as a Category 3 with winds of 125 m.p.h.

“It could be quite devastating — especially some of those high-rise buildings are just not rated to sustain that wind load,” said Jamie Rhome, acting deputy director of the National Hurricane Center.

The severe damage from Hurricane Laura, which struck southwest Louisiana last year as a Category 4 storm, was caused primarily by high winds. The storm caused 42 deaths and damage costing more than $19 billion.

Ida’s rainfall also threatens to exceed Katrina’s highs.

The National Hurricane Center estimates that Ida will drench the Gulf Coast with 8 to 16 inches of rain and perhaps as much as 20 inches in some places. Katrina brought 5 to 10 inches of rain, with more than 12 inches in some areas.

“That is a lot of rainfall,” Mr. Rhome said of the forecast for Ida. “Absolutely the flash flood potential in this case is high, very high.” Combined with storm surge, he said, that much rain could have a “huge and devastating impact to those local communities.”

NEW ORLEANS — As storm-force winds and rainfall reached the New Orleans area on Sunday morning, knocking out power in some places and making highway travel dangerous, it was already too late to leave. Still, some people in the city were second-guessing their decision to stay.

“I’m a little nervous,” said Le-Ann Williams, 30, as she cooked breakfast and watched the forecast in her New Orleans East apartment.

The roads west and east of New Orleans were parking lots for much of Saturday as tens of thousands of people tried to make their way out of the storm’s predicted path. It took Robert Green Sr. 16 hours to get to Houston from New Orleans on Saturday, ordinarily a five-hour drive.

At the same time, thousands more decided to stay put.

Shawn Kelly meant to leave. He does not have a car, so he booked a flight out. But by Saturday afternoon, he got a notification that the flight had been canceled, and social media posts showed hourslong lines at the airport.

So the stage was set: He’d try to ride out Hurricane Ida in his parents’ home in the Uptown area of New Orleans — the same place where he and his family tried to ride out Katrina in 2005, when he was 10 years old. Back then, the family wound up having to be rescued, a scenario he hopes won’t be repeated.

“I wish I could leave, because the next couple days without power are going to be the worst part,” Mr. Kelly said. “I’m worried about the aftermath, more so than the storm, because that was the thing with Katrina; it was the aftermath. I’m always worried about what comes after.”

For New Orleans leaders, the question is what will happen to those who stayed behind if Ida’s destruction makes conditions inhabitable.

The answer is “post-storm evacuation,” said Collin Arnold, the city’s director of emergency preparedness. Urban search-and-rescue teams were prepared, and buses have been placed on high ground, ready to carry people out of town on Monday, once the storm blows through.

Older people in the city often talk proudly of never having evacuated, even in the face of serious storms like Hurricane Betsy in 1965. But Mr. Arnold said the plans for post-storm rescues were not an endorsement of that bravado, just an acknowledgment that fast-moving storms like Ida may leave little time for evacuation.

“We’re not intentionally choosing it,” he said. “It’s changes in the climate that are doing it to us.”

Evacuation is a crucial part of the disaster plan in a city where one in five households lack cars. But to be effective, the evacuation process should begin 72 hours before a storm hits. And Ida, a sprinter of a storm, was little more than a tropical disturbance in the Caribbean on Thursday afternoon, when Mayor LaToya Cantrell would have had to issue the order.

“Time was not on our side,” Ms. Cantrell said on Friday as she encouraged residents to voluntarily evacuate, but it was too late for a mandatory order.

Tens of thousands of people weighed their options and decided to hunker down. Some were optimistic that the city’s improved levees and pumps would hold this time. For others who had already paid their monthly bills, money was too short to travel now.

“Evacuation will always be the safest option for major hurricanes,” Mr. Arnold said. “Before Katrina, there were locals who would say, ‘I don’t leave for storms.’ Katrina changed that mind set. Now climate change may be changing it for us again.”

— Katy Reckdahl and Chelsea Brasted

Hurricane Ida is the first major storm to strike the Gulf Coast during the 2021 season, hitting a region in many ways still grappling with the physical and emotional toll of a punishing run of hurricanes last year.

The Atlantic hurricane season of 2020 was the busiest on record, with 30 named storms, 13 of which reached hurricane strength. There were so many storms that forecasters ran through the alphabet and had to take the rare step of calling storms by Greek letters.

Louisiana was dealt the harshest blow, barraged repeatedly by storms, including Hurricane Laura, which was one of the most powerful to hit the state, trailed six weeks later by Delta, which was weaker than Laura but followed a nearly identical path, inflicting considerable pain on communities still gripped by the devastation from the earlier storm.

The state is struggling to claw its way back. Gov. John Bel Edwards of Louisiana said the state had $3 billion in unmet recovery needs. In Lake Charles, which was ravaged by direct hits from both hurricanes followed by a deadly winter storm and flooding in May, local officials recently renewed a plea for federal aid as the city has failed to regain its footing; much of it has yet to recover and many residents, unable to find adequate or affordable housing, have fled.

The impact of Ida underscores the persistient peril facing coastal communities as a changing climate helps intensify the destructive force of the storms that have always been a seasonal part of life in the region.

President Biden cited the growing danger in May when he announced a significant increase in funding to build and bolster infrastructure in communities most likely to face the wrath of extreme weather.

People in Louisiana, which was hard-hit by storms last year, were coping on Sunday morning with Hurricane Ida a powerful Category 4 storm lashing the coast and nearing landfall on its way toward New Orleans.

Here’s how to prepare for a hurricane or tropical storm.

Before the storm

The Federal Emergency Management Agency recommends signing up for local weather alerts, and learning about evacuation routes.

The National Weather Service suggests having a battery-operated radio ready to go for news updates in case of a power loss, t.

The Red Cross suggests preparing an emergency kit with the following items: water (enough for one gallon per person per day); nonperishable food; a flashlight; a first aid kit; a multipurpose tool; hand sanitizer or sanitation wipes; important personal documents; blankets; and maps of the area.

FEMA also recommends preparing a “go bag” with essential items like medications, and securing important documents like financial, medical, school and legal records.

During the storm

FEMA suggests staying away from windows, which can be damaged in high winds. Generally it is best to seek shelter on the lowest level of a home, in an interior room like a closet. But if flooding is likely, seeking higher ground may be a better plan.

The National Weather Service warns that drivers should never try to drive through floodwaters on roads. Two feet of flowing water is enough to float a vehicle.

Residents should heed guidance from local officials, and promptly follow any evacuation orders.

After the storm

Anyone who evacuated should wait to return until local officials say it is safe to do so. Flooded roads can remain dangerous once a storm has passed, and fallen debris, weakened trees and structures and downed power lines can pose hazards.

Water sources can become contaminated. Residents in an area affected by a storm should avoid drinking tap water unless local officials say it is safe to use.

Hurricanes and tropical storms are defined by their powerful winds. But the storm surges they produce can often prove just as destructive in coastal communities.

Hurricane Ida was expected to create dangerous storm surges in parts of Louisiana and Mississippi.

Storm surge is defined as an abnormal rise in the ocean level generated by a storm, over and above the predicted astronomical tide. The surges are produced by ocean water moving inland, pushed by the force of the wind.

In the open ocean, hurricanes can pound the water without producing a surge. But near the coast, the shallower water is blown inland, threatening property and lives.

The highest surge will occur along the immediate coast in areas of onshore winds, where the high water will be accompanied by large and dangerous waves, the National Hurricane Center said.

The extent of surge-related flooding depends on the timing of the surge and the tidal cycle, and can vary greatly over short distances, the center said.

In 2008, Ike, a Category 2 hurricane that made landfall near Galveston Island in Texas, produced surges of 15 to 20 feet above normal tide levels, the center said. Property damage was estimated at $24.9 billion.

The National Hurricane Center said that areas that are placed under a storm surge warning are at risk of “life-threatening inundation.” People in those areas should heed any evacuation instructions from local officials, the center said.

NEW ORLEANS — With Hurricane Ida likely to bring powerful winds and heavy rain to their city, residents of New Orleans faced a familiar choice: flee or hunker down for the duration.

The storm was expected to make landfall by Sunday afternoon or evening and officials urged people who intended to evacuate to do so by Saturday. Residents came to a variety of decisions on the matter.

Lacy Duhe, 39, and Jeremy Housely, 42, opted to hunker down in their second-story apartment on Deslonde Street in New Orlean’s Lower Ninth Ward. If they evacuated and ended up in a shelter, they said, they worried about the risk of their unvaccinated children contracting Covid-19. They also had just paid their monthly bills and could not afford to go anywhere.

“It feels serious,” said the couple’s 11-year-old daughter, Ja-nyi. “I wasn’t born during Katrina time. But I know it knocked down a lot of places.”

Mary Picot, 71, walked out the door on Saturday afternoon carrying bags of snacks and medicine. She wasn’t worried about flooding and believed the levees would hold. It was the threat of power outages that convinced her to leave.

“My husband is diabetic,” she said. “We have to keep his medicine cold.”

Donald Lyons, 38, was packing up a silver Nissan sedan Saturday afternoon under a cloud-filled sky in Hollygrove, one of the traditionally Black working class neighborhoods that flooded badly when Katrina hit. The car, carrying his wife, three children and mother-in-law, was full of bags and bedding. They were heading to Sugar Land, Texas, 27 miles southwest of Houston, where they had family that had left after Katrina, 16 years ago, and never come back.

“I’m just trying to get somewhere safe,” Mr. Lyons said.

Down the block, Barbara Butler, 65, a housekeeper, said she thought the city was safer now with all of the new flood protection. She intended to ride out the storm at home.

“It gave us some relief,” she said. “It’s better than no relief.”

She was sitting on the porch with her husband, Curtis Duck, 63, and her brother, Ray Thomas, in a house that Ms. Butler said was flooded with eight feet of water after Katrina.

Mr. Duck said he was sick of evacuating time and again.

“We listen to the news,” he said. “People telling us to go, go, go.”

Victor Pizarro, a health advocate, and his husband decided to ride out the storm in their home in the Gentilly Terrace neighborhood, although they said they would leave town if they lost power for an extended period.

“It’s definitely triggering to even have to think about this and make these decisions,” Mr. Pizarro said in a telephone interview while he drove across town in search of a spare part for his generator. “It’s exhausting to be a New Orleanian and a Louisianian at this point.”

Andy Horowitz and his family decided to vacate their home in the Algiers Point neighborhood, which sits directly across the Mississippi River from the French Quarter. Mr. Horowitz is the author of “Katrina: A History, 1915-2015,” and he is among those scholars and Louisiana residents who fear that the city’s new flood protection system, as massive as it is, may prove to be inadequate for a sinking city in the likely path of more frequent and powerful storms in the age of climate change.

“Every summer, New Orleans plays a game of Russian roulette, and every summer we pull the trigger,” Mr. Horowitz said.

Hurricane Ida intensified overnight, becoming a Category 4 storm over the course of just a few hours. The rapid increase in strength raises questions about how much climate change is affecting hurricanes in the Atlantic Ocean. While researchers can’t say for sure whether human-caused climate change will mean longer or more active hurricane seasons in the future, there is broad agreement on one thing: Global warming is changing storms.

Scientists say that unusually warm Atlantic surface temperatures have helped to increase storm activity. “It’s very likely that human-caused climate change contributed to that anomalously warm ocean,” said James P. Kossin, a climate scientist with the National Oceanic and Atmospheric Administration. “Climate change is making it more likely for hurricanes to behave in certain ways.”

Here are some of those ways.

1. Higher winds

There’s a solid scientific consensus that hurricanes are becoming more powerful.

Hurricanes are complex, but one of the key factors that determines how strong a given storm ultimately becomes is ocean surface temperature, because warmer water provides more of the energy that fuels storms.

“Potential intensity is going up,” said Kerry Emanuel, a professor of atmospheric science at the Massachusetts Institute of Technology. “We predicted it would go up 30 years ago, and the observations show it going up.”

Stronger winds mean downed power lines, damaged roofs and, when paired with rising sea levels, worse coastal flooding.

“Even if storms themselves weren’t changing, the storm surge is riding on an elevated sea level,” Dr. Emanuel said. He used New York City as an example, where sea levels have risen about a foot in the past century. “If Sandy’s storm surge had occurred in 1912 rather than 2012,” he said, “it probably wouldn’t have flooded Lower Manhattan.”

2. More rain

Warming also increases the amount of water vapor that the atmosphere can hold. In fact, every degree Celsius of warming allows the air to hold about 7 percent more water.

That means we can expect future storms to unleash higher amounts of rainfall.

3. Slower storms

Researchers do not yet know why storms are moving more slowly, but they are. Some say a slowdown in global atmospheric circulation, or global winds, could be partly to blame.

In a 2018 paper, Dr. Kossin found that hurricanes over the United States had slowed 17 percent since 1947. Combined with the increase in rain rates, storms are causing a 25 percent increase in local rainfall in the United States, he said.

Slower, wetter storms also worsen flooding. Dr. Kossin likened the problem to walking around your back yard while using a hose to spray water on the ground. If you walk fast, the water won’t have a chance to start pooling. But if you walk slowly, he said, “you’ll get a lot of rain below you.”

4. Wider-ranging storms

Because warmer water helps fuel hurricanes, climate change is enlarging the zone where hurricanes can form.

There’s a “migration of tropical cyclones out of the tropics and toward subtropics and middle latitudes,” Dr. Kossin said. That could mean more storms making landfall in higher latitudes, like in the United States or Japan.

5. More volatility

As the climate warms, researchers also say they expect storms to intensify more rapidly. Researchers are still unsure why it’s happening, but the trend appears to be clear.

In a 2017 paper based on climate and hurricane models, Dr. Emanuel found that storms that intensify rapidly — the ones that increase their wind speed by 70 miles per hour or more in the 24 hours before landfall — were rare in the period from 1976 through 2005. On average, he estimated, their likelihood in those years was equal to about once per century.

By the end of the 21st century, he found, those storms might form once every five or 10 years.

“It’s a forecaster’s nightmare,” Dr. Emanuel said. If a tropical storm or Category 1 hurricane develops into a Category 4 hurricane overnight, he said, “there’s no time to evacuate people.”