Catastrophe in the making: Extremely dangerous Hurricane Ida to impact Louisiana late Sunday

The ingredients are coming together for Hurricane Ida to strengthen and grow larger before it plows into southern Louisiana on Sunday — 16 years to the day after Katrina made landfall on the eastern edge of the state. There is a laundry list of reasons that the impact from Ida will likely be near the top of the scale.

• There are signs that Ida is wrapping up. Thunderstorms have almost encircled the center.
• Ida is forecast to run over a pool of very deep warm water called the loop current. That’s what Katrina did, which contributed to it exploding into a Category 5 in the middle of the Gulf. That doesn’t mean Ida will become a Cat 5, but it means that it is likely to rapidly strengthen. The current forecast is for it to become a solid Cat 4.
• Computer forecast models have consistently increased their predictions for Ida’s maximum winds
• The upper-level winds are forecast to be conducive for strengthening
• Ida won’t be as physically big across as Katrina, but it is forecast to grow in size. The wider the storm, the more storm surge it produces.
• The water close to the Louisiana coast is much warmer than average
• This has already been one of the wettest summers in the record books in southeastern Louisiana. Flash Flood Watches were in effect just yesterday well in advance of Ida.
• Ida is forecast to dump a foot to a foot and a half of rain, maybe more.
• Ida is forecast to slow down as it moves over the Louisiana coast prolonging the misery from the flooding rain, the storm surge, and the punishing wind.

The only apparent inhibiting factors would seem to be internal structure issues that are impossible to forecast. Sometimes, despite conditions conducive for strengthening, storms don’t realize their potential. Also, extremely strong hurricanes normally go through a process of replacing their eyewall with a new one. The winds usually weaken during that cycle.

We can only hope that one or both of those possibilities come to pass. All indications are that this will be a catastrophic hurricane in parts of Louisiana. But there are degrees of catastrophes.

The odds now favor the hurricane taking a track far enough west of the New Orleans that the giant post-Katrina system that protects the city should be able do its job. Called the Greater New Orleans Hurricane and Storm Damage Risk Reduction System, it’s an extraordinary system of walls, levees, and gates. It’s massive and it’s strong. It should protect the city and other areas inside its walls.

Outside those giant barriers, communities are protected by levees of different heights and strengths. Mandatory evacuations were ordered outside the Greater New Orleans system, and a voluntary evacuation was issued for residents living inside the walls.

While people in the city should be safe from storm surge, a massive flood from torrential, relentless rain will likely cause major problems. In addition, the power will almost certainly be out, so it will not be pleasant to stay, even if it’s safe.

Remember, much of the area is below sea level, so if levees fail, the flooding is automatically extensive and deep. That’s why it’s important to get people to high ground.

We talk mostly about New Orleans because it is the biggest city, and Katrina is still fresh in our minds. But Baton Rouge, the Louisiana capital, is closer to the direct path of Ida, if nothing changes. Even though it’s 80 miles inland, Ida’s impact there will likely be extreme from the wind and rain. Ida’s effects will extend as far east as Alabama.

This is the last day to prepare. The weather will start deteriorating tonight or early tomorrow. Let’s hope folks there don’t waste a minute.

The disaster will take a days to unfold as Ida moves slowly inland. Flooding rain is forecast over a large area in the South.

Here are the Key Messages from the National Hurricane Center:

1. Hurricane and tropical storm conditions are ending over Cuba. However, Ida will continue to bring periods of heavy rain across western Cuba through today that may lead to flash flooding and mudslides.
2. There is a danger of life-threatening storm surge inundation Sunday along the coasts of Louisiana and Mississippi within the Storm Surge Warning area. Extremely life-threatening inundation of 10 to 15 feet above ground level is possible within the area from Morgan City, Louisiana, to the Mouth of the Mississippi River. Interests throughout the warning area should follow any advice given by local officials.
3. Ida is expected to be an extremely dangerous major hurricane when it reaches the coast of Louisiana. Hurricane-force winds are expected Sunday in portions of the Hurricane Warning area along the Louisiana coast, including metropolitan New Orleans, with potentially catastrophic wind damage possible where the core of Ida moves onshore. Actions to protect life and property should be rushed to completion in the warning area.
4. Ida is likely to produce heavy rainfall later Sunday into Monday across the central Gulf Coast from southeast Louisiana to coastal Mississippi resulting in significant flash and riverine flooding impacts. As Ida moves inland, flooding impacts are possible across portions of the Lower Mississippi and Tennessee Valleys.

Out in the Atlantic there are three areas noted by the National Hurricane Center. None are expected to be a threat to land.