After making landfall in western Cuba on Friday night as a category 1 hurricane with 80 mph winds, Hurricane Ida is now in the Gulf of Mexico, headed northwest at 15 mph towards Louisiana. Ida was somewhat disorganized Saturday morning after its encounter with Cuba, but quickly reorganized Saturday afternoon and appears on track to strike a devastating blow to Louisiana Sunday as a major hurricane. Update (3 a.m. EDT Sunday): Ida rapidly intensified on Saturday night and reached Category 4 strength at 3 a.m. EDT, with top sustained winds of 130 mph. Further strengthening was possible.

Update (1:20 p.m. EDT Sunday): Ida made landfall around 12:55 p.m. EDT near Port Fouchon, LA, as an extremely dangerous category 4 hurricane, with top winds of 150 mph.

Track forecast for Ida 

There is little drama in the track forecast for Ida. A ridge of high pressure centered near the Southeast U.S. coast will keep Ida moving to the northwest at 10 to 15 mph for the next two days, and there is little doubt that central Louisiana will receive a direct strike on Sunday afternoon or evening. After landfall, Ida is expected to turn more to the north and slow down to a forward speed of 5-10 mph, resulting in an extended period of heavy rains.

Intensity forecast for Ida 

Ida has not rapidly intensified as soon as anticipated, which is good news, since it means the hurricane will be unable to push as large a storm surge to the coast. However, conditions are in place for Ida to rapidly intensify right up until landfall, with light to moderate wind shear of 5-15 knots, a moist atmosphere, and very warm sea surface temperatures of 30-31 degrees Celsius (86-88°F). With high temperatures extending to unusual depths, these waters give the system plenty of ocean heat to power it. Ida is predicted to pass over a warm eddy in the Gulf of Mexico with unusually high heat content Saturday night into Sunday, and the heat from this eddy can fuel Ida’s rapid intensification.

New Orleans’ impossible situation

A mandatory evacuation was issued for portions of New Orleans outside of their levee system on Friday, and a voluntary evacuation for inside the levee system. However, no mandatory evacuation was ordered for the city because officials judged there was insufficient time to set up contraflow, having all lanes of traffic converted to lead out of town.

Many have criticized this decision, but New Orleans found itself in an impossible situation: the city needs a full 72 hours to fully evacuate, and making reliable intensity forecasts that far in advance is very difficult. We will have to accept New Orleans’ vulnerability to major hurricanes unless tens of billions are spent to upgrade the city’s defenses to category 5 capability. As discussed in yesterday’s post, there is reason to be optimistic that New Orleans’ levee system will withstand Ida’s storm surge: The 7-11′ surge predicted for the city is below the maximum surge that Hurricane Isaac of 2012 brought.

Louisiana is currently suffering from one of the worst COVID-19 outbreaks in the country, so not ordering a mandatory evacuation of New Orleans will reduce much COVID-19 spread among the residents of New Orleans (who have a relatively high one-shot vaccination rate of 62%) than otherwise could have occurred. This may have factored into the decision not to order a mandatory evacuation.

Figure 1. Map of the Port of South Louisiana, on the Lower Mississippi River between Baton Rouge and New Orleans. Note the long list of key industrial sites. (Image credit: Port of South Louisiana)

Likely significant damage to key industrial corridor

Ida is predicted to track over one of the most critical industrial areas in the U.S.: the industrial corridor between Baton Rouge and New Orleans. Not only is the region home to dozens of key petrochemical sites, and crisscrossed by important pipelines, it also has three of the fifteen largest ports in America: the largest bulk cargo port in the world, the Port of South Louisiana, which lies along a 54-mile stretch of the Mississippi River; the nation’s largest export grain port, the Port of New Orleans; and the Port of Greater Baton Rouge, the nation’s 10th-largest port. These three ports handle 55-70% of all U.S. grain exports to the world, supplied by barges moving downriver.

Going upriver, Mississippi River barges transport petrochemicals, fertilizers, and raw materials essential for the functioning of U.S. industry and agriculture, making the Mississippi River the lifeblood of the American economy. If the ports of the Mississippi River are closed for an extended period of time, the entire U.S. economy suffers, with impacts to the global economy and world food supplies; world food prices, vulnerable to extreme weather shocks, in May of 2021 hit their highest levels since 2011.

The 11 a.m. EDT Saturday National Hurricane Center forecast takes the center of Ida about 20 miles to the west of the Port of South Louisiana, putting this critical port and much of the key industrial corridor at high risk of severe wind damage from the hurricane. The hurricane is also predicted to pass directly over the Port of Greater Baton Rouge. If Ida hits Louisiana as a major hurricane, expect severe wind damage to these two ports, and potential storm surge damage to the Port of New Orleans.

The 2006 report “Case Study of the Transportation Sector’s Response to and Recovery from Hurricanes Katrina and Rita” said that in the wake of Hurricane Katrina in August 2005, the Port of New Orleans was closed for 15 days; the Port of South Louisiana, less damaged, was closed for five days. Barge traffic was severely impacted for many weeks, in part because the hurricane destroyed many U.S. Coast Guard’s navigation aids – the system of buoys, beacons, and lighthouses that facilitate safe navigation. The Coast Guard estimated that some 1,800 aids to navigation were missing, relocated, or destroyed because of Hurricane Katrina. More than 300 barges along the river were set adrift by flood surges and wind, sunk, or significantly damaged, posing further risks to navigation. Ida may have similar impacts to navigation.

Figure 2. Boats stranded on the banks of an oil-slicked waterway on September 12, 2005, in Venice, Louisiana, after Hurricane Katrina. The Mississippi River is in the distance. (Image credit: Lieut. Commander Mark Moran, NOAA Corps)

Fortunately, Ida is hitting well before the peak of the corn and soybean export season. After Hurricane Katrina, most of the Mississippi River ports were back in service in time to handle the peak export demand later in the fall of 2005. With a Katrina (or Ida) strike late in the hurricane season, delays and damage to corn and soybean exports and other agricultural exports might have been severe.

Ida’s damages to the region’s transportation infrastructure could well take months to recover from, with key bridges destroyed and hundreds of miles of roads and railroads severely damaged or destroyed. The Louis Armstrong New Orleans International Airport could be forced to close for some time: It was heavily damaged by Katrina and closed for 16 days. Likewise, damage to the electrical power distribution system may be widespread and severe, taking weeks or even months for full recovery.

As occurred in the wake of Katrina, lack of electrical service and of labor may be primary factors hindering efforts to resume transportation services. Truck, port, railroad, and road employees whose homes are damaged or destroyed in the storm may have evacuated from the region.

Figure 3. Areas of storm surge inundation (yellow colors) from category 4 Hurricane Betsy of 1965. (Image credit: U.S. Army Corps of Engineers, via Westerink et al., 2008, “A Basin to Channel-Scale Unstructured Grid Hurricane Storm Surge Model Applied to Southern Louisiana,” Monthly Weather Review 136(3):833-864)

Vulnerability of Waterford 3 nuclear plant to storm surge

Although it lies 65 miles inland from the south coast of Louisiana, the Waterford 3 nuclear generating station, located at an elevation of 10-15 feet on the south shore of the Mississippi River, is vulnerable to storm surge from a major hurricane. Hurricane Betsy, a category 4 storm that hit Louisiana in 1965, brought a storm surge to the edge of the plant’s location (Figure 3).

According to a 2019 analysis by Bloomberg, the Waterford 3 plant is designed to withstand a maximum storm surge of 23.7 feet above sea level, or about 10 feet higher than the plant’s elevation. Update: According to an email received from a former worker, while the grounds surrounding the reactor containment building are at 10-15 feet, the base elevation of the building is 21 feet. The plant can take a storm surge up to 29.3 feet above sea level, according to the updated license renewal. The reactor containment building was designed to handle a levee failure due to an earthquake, and can survive a jet airplane crash.

According to NOAA’s National Storm Surge Hazard database, a worst-case category 3 hurricane could flood the plant to a depth of 3’, while a worst-case category 4 hurricane could flood the plant to a depth of more than 9’ – near its design limit. Fortunately, storm surge modeling by Louisiana State University using the 11 a.m. EDT Saturday NHC forecast showed Ida’s storm surge stopping just short of the plant (Figure 4).

Figure 4. Predicted storm surge from Hurricane Ida, with the 11 a.m. EDT Saturday NHC advisory positions overlaid. (Image credit: CERA/Louisiana State University)

After the 2011 disaster at Japan’s Fukushima nuclear power plant, the Waterford 3 plant moved to store all of its emergency generators, pumps, and other essential safety equipment in a 30-foot flood-proof concrete bunker – a system called Flex, for Flexible Mitigation Capability. The bunker has manually operated and powered sump pumps to remove water in the event of a flood.

Ida is currently not predicted to bring storm surge flooding to the plant, but that could change if the hurricane tracks more to the right side of the cone of uncertainty and/or grows stronger than predicted. In its 11 a.m. EDT Saturday wind probability forecast, NHC gave the Waterford 3 site a 50% chance of experiencing hurricane-force winds from Ida. Point is: It’s a bad idea to site a nuclear power plant in a location subject to hurricane-force winds and storm surge flooding. Though the plant is designed to handle what Ida is likely to throw at it, unexpected bad things can happen in intense disaster situations.

Vulnerability of the offshore oil industry

Port Fourchon, located on the extreme south coast of Louisiana, is predicted to be near the strong right eyewall of Ida, where a storm surge of 10-15 feet and hurricane-force winds are predicted. The port serves as a major center for oil importation and a land base for offshore oil drilling. The port handles 18 percent of domestic oil and gas and 13 percent of the nation’s foreign energy imports. There are more than 600 oil platforms within a 40-mile radius of Port Fourchon, most resupplied from facilities at the port. Ida is likely to significantly damage the port, potentially leaving it cut off from the rest of the state due to storm surge flooding of Highway 1, as occurred in Hurricane Katrina. According to Reuters, U.S. oil and gas companies on Friday cut more than 1.6 million barrels of oil production, exceeding the cuts done during 2005’s devastating Katrina.

Figure 5. Predicted wave heights in the Gulf of Mexico at 2 a.m. EDT Sunday, August 29, 2021. (Image credit: weathermodels.com)

Ida will bring huge waves to the Gulf of Mexico

Ida is predicted to bring huge waves in excess of 40’ to the Gulf of Mexico on Sunday. It’s worth pointing out that the oil industry’s infrastructure is vulnerable to big hurricane waves: The Taylor Oil Spill started in 2004 after Hurricane Ivan brought 70’ waves off the coast of Louisiana that caused submarine landslides that took out a drilling rig. The site still leaks oil.

Figure 6. Paths of all historical category 4 and 5 hurricanes to pass near Southeast Louisiana.

In southeast Louisiana history, only three Cat 4 landfalls (and no Cat 5s)

In the 170 years of data stored in the NOAA historical database, there are surprisingly few category 4 and 5 hurricanes that have approached southeast Louisiana at that strength, and even fewer that made landfall. The map above shows all hurricanes known to have passed within 80 nautical miles (92 miles) of the city of Houma at Cat 4 or 5 strength. This circle encompasses the southeast Louisiana coast from Vermilion Bay east to the Mississippi border.

Only three hurricanes since 1851 have made landfall in southeast Louisiana at Cat 4 strength, and none at Cat 5 strength, based on data from the HURDAT2 reanalysis project. It’s worth stressing that even a hurricane that weakens just before landfall can still deliver extreme storm surge generated for hours beforehand: That was the case with Katrina in 2005, which dropped from Cat 5 to Cat 3 strength just before its Louisiana landfall. Also, some areas in this circle have had severe impacts from hurricanes making landfall well west of it: for example, 2005’s sprawling Hurricane Rita brought major storm surge to the area as it crashed inland as a Cat 3 in far western Louisiana.

1856: The Last Island Hurricane struck the coast south of Houma on August 10 with Cat 4 sustained winds of 150 mph, the state’s highest landfall intensity on record until it was tied by the 202o Hurricane Laura. The hurricane passed directly over Isle Dernière (French for “last island”) with a 10- to 11-foot storm surge, destroying every structure on the island, including a resort hotel, and taking some 200 lives. Smithsonian.com has a compelling retrospective.

1893: The Chenière Caminada Hurricane struck the Mississippi Delta on a recurving path from southwest to northeast on October 1-2 as a Cat 4 with top winds of 130 mph. It destroyed nearly every structure in the town of Chenière Caminada and killed more than half of its 1,500 residents. The storm surge was estimated at 16 feet, and the hurricane still ranks as the deadliest in Louisiana history, with an estimated 2,000 fatalities. Country Roads has more on this tragic storm.

1965: Hurricane Betsy was the nation’s first billion-dollar hurricane (in 1965 USD) and the most damaging storm to affect Louisiana until 2005’s Hurricane Katrina. After destructive landfalls in the Bahamas and South Florida, Betsy entered the Gulf and made landfall on September 10 near Grande Isle with top sustained winds of 130 mph. Betsy was classified as a category 3 landfall until HURDAT2 reanalysis found that its top winds were in the Cat 4 range. Massive flooding in New Orleans prompted construction of the flood-protection system that was upgraded after Katrina.

Figure 7. Infrared image of Tropical Depression 10 in the central tropical Atlantic at 1655Z (12:55 p.m. EDT) Saturday, August 28, 2021. (Image credit: tropicaltidbits.com)

Tropical Depression 10 likely to become tenth storm of the year

The NHC is predicting that Tropical Depression 10 will become Tropical Storm Julian this weekend in the remote central Atlantic. TD 10 was located on Saturday about 800 miles east of the Leeward Islands with top winds of 35 mph. Strong wind shear of around 20 knots was pushing most of TD 10’s expansive but disorganized convection toward the east side of the system. The unrelenting shear and a relatively dry atmosphere (midlevel relative humidity of 50-5%) will continue through at least Monday, and water temperatures of 27-28 degrees Celsius (81-82°F) are not exceptionally warm, so TD 10 is unlikely to develop beyond minimal tropical storm strength as it drifts northward, eventually becoming swept up in a midlatitude storm system. TD 10 is not a threat to land.

Figure 8. Infrared image of Hurricane Nora just off the Mexico coast at 1650Z (12:50 p.m. EDT) Saturday, August 28, 2021. (Image credit: RAMMB/CIRA/CSU)

Hurricane Nora heading for Gulf of California

There’s another hurricane not too far away from Ida that could affect the U.S. later next week. At 11 a.m. EDT Saturday, Hurricane Nora was spinning just off the west coast of Mexico, about 425 miles southeast of Cabo San Lucas, with top winds of 80 mph. As it heads northwest, staying close to the Mexican coast, Nora will encounter exceptionally warm SSTs of 30-31 degrees Celsius (86-88°F), and moderate wind shear of 10-15 knots will drop to 5-10 knots on Sunday. Nora could strengthen sharply this weekend in a moist atmosphere (a midlevel relative humidity around 75%). The 12Z Saturday SHIPS model gave Nora a 28% chance of rapidly intensifying by 35 mph in 24 hours, which would make it a major category 3 hurricane.

The NHC forecast has Nora moving north through the Gulf of California as a hurricane on Monday through Tuesday, then making landfall by Wednesday in northwest Mexico as a tropical storm. Any small change in track could weaken Nora much more quickly. Moisture streaming north from Nora next week may bring heavy rains from Arizona to the northern Great Plains later in the week.

Also see: How climate change is making hurricanes more dangerous, by meteorologist Jeff Berardelli

Editor’s note: Just this month, the new IPCC Sixth Assessment Report announced that “it is likely that the global proportion of major (Category 3-5) tropical cyclone occurrence has increased over the last four decades.”

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Jeff Masters

Jeff Masters, Ph.D., worked as a hurricane scientist with the NOAA Hurricane Hunters from 1986-1990. After a near-fatal flight into category 5 Hurricane Hugo, he left the Hurricane Hunters to pursue a...

Bob Henson

Bob Henson is a meteorologist and journalist based in Boulder, Colorado. He has written on weather and climate for the National Center for Atmospheric Research, Weather Underground, and many freelance...