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  • Writer's pictureBryan Norcross

Misunderstanding Ida’s forecast; the flood threat spreads north; Larry forms near Africa

Lessons will roll in over the weeks and months to come as the full impact of Hurricane Ida in Louisiana is better understood. In the broad view, the big levees held, the electricity failed, and the small communities in the direct path of the core of the hurricane were devastated from some combination of wind and water.

Analyses of the structural failures from roofs that flew off to transmission towers that toppled will provide a guide to limiting similar events in the future. Whether state and local governments will learn the lessons and create a better laws and policies is another question. Miami-Dade’s determination to create a world-standard building code for hurricanes after Hurricane Andrew is the model.

A big lesson transcends Ida, however, and it’s important for everybody in the hurricane zone. Unfortunately, it comes up again and again.

A continuing communications challenge was on full display when a major university in New Orleans put out a misleading statement about Hurricane Ida’s forecast from the National Hurricane Center. The university claimed that the official forecast on Saturday morning misled them, which apparently affected how they handled the emergency. They elected to house thousands of students in the city to ride out the storm.

In reality, the National Hurricane Center forecasts for Hurricane Ida were spectacularly good – much better than average. New Orleans was under a hurricane warning and in the cone Saturday morning, the day before the storm hit. Ida bobbed and weaved its way into Louisiana, but the center stayed inside the cone and did nothing that an experienced hurricane tracker would call surprising.

It was annoying and upsetting for people in New Orleans, yes. But surprising? It shouldn’t have been. So how could a major university misunderstand the NHC’s forecast? And in New Orleans, of all places.

Dr. Marshall Shepherd pointed out in a post in Forbes last night that the emergency management team at Tulane is highly regarded. This just further shows how challenging it is for people to understand their risk when a hurricane is threatening.

In the end, we’re all trying to evaluate our risk. The problem is, it is human nature to hopecast. The university officials were evidently hoping that Ida would stay near the center of the cone or maybe wobble in the other direction. On the other hand, planners who properly utilize the forecast to make decisions fight that tendency. They understand that a wobble in any direction is possible – for better or worse.

There is no doubt that decision-making is difficult when a hurricane is bearing down, Covid is raging, and you are responsible for thousands of students. In the end, it might very well have been the best plan to shelter the students in the city instead of subjecting them to an evacuation frenzy. It’s hard to say.

But institutions should own their decisions, and not blame the forecasters because they didn’t allow for a wobble in their plan. It comes down to planing for the worst reasonably possible outcome, and leaving hope out of it.

The National Hurricane Center adopts this philosophy. What are the near-worst-case conditions a given location is likely to experience? Certainly, worse could happen, but the odds are quite low that the storm will be worse than the warnings and the forecasts portend.

It’s the only workable system when you are dealing with a hurricane that can wobble and strengthen in unforecastable ways. The questions is, what are the bounds? Given what we know, what level of danger is the storm unlikely to exceed. The NHC warnings attempt to convey that threshold.

Conveying the risk with the acknowledgement that not everyone in the warned area will see the extreme conditions, but everyone could, is tricky business.

It’s hard to convey risk. Numbers alone don’t do it. The message has to have a tone and a clarity that communicates the risk in a way that people can feel it. Ideally, residents are spurred to take action before the storm, and to feel good when the odds fall their way and the storm isn’t as bad as they were told it could be.

Whether you’re running a university or a household, the right question to ask is: What is the course of least regret? They are easy words to say, but harder to follow when a big decision has to be made.

As Louisiana struggles to get on its feet, Ida isn’t finished. A tremendous amount of rain is forecast today in the mountains of West Virginia, Maryland, and southern Pennsylvania, and then spreading into the Northeast. The current forecast is for 3 to 8 inches of rain, with more in some locations. That’s a dangerous amount of rainfall in high terrain with rivers, creeks, and valleys. The big cities of the Northeast including New York are in line for torrential rain as well.

On the other side of the Atlantic, Tropical Storm Larry has formed. The system is forecast to intensify into a strong hurricane while it turns north into the central Atlantic before it gets to the islands. For the next several days, Larry won’t be a problem. After that, we need to be sure it continues to the north. Its long-term prospects are still a bit murky.

In reality, nobody should make hurricane forecasts more than a week out, so we’ll wait to evaluate how the weather pattern is going to develop, just to be sure.

In the Caribbean, there is a tropical disturbance in the same area that Ida came from, but the pattern is different now. There’s a low chance that this will develop because it’s forecast to track near or over Central America. But again, once it gets into the Gulf several days from now, we’ll want to be sure it doesn’t wander north over the warm water.

Tropical Depression Kate will fade out in the central Atlantic.

Nothing else is in the pipeline at the moment.


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