World - The Hurricane Otis Forecast Bust And An Important Lesson

My mouth dropped when I saw that a potential Category 5 hurricane was going to make landfall near Acapulco, Mexico.

It is rare to see a hurricane of such extreme intensity directly impact a city with such a large population, and the outcome unfortunately was as expected. Nahel Belgherze posted on the platform X, “Acapulco, Mexico might have just become the first city of over a million inhabitants in the world to experience the eyewall of a Category 5 storm.” Images of the damage suggest that it will take years for the region to recover. Was it a forecast bust and what can we learn?

There is no doubt that from an intensity perspective, Hurricane Otis far exceeded expectations. It exhibited rapid intensification, which is at least a gain of 35 mph of wind speed in less than 24 hours. In fact, Otis went from a Tropical Storm to a Category 5 hurricane in half of that time. This pace is what I have called hyper-intensification in recent storms. The models were way off so let’s go ahead and call it a bust.

Even with such hyper-intensification, National Hurricane Center forecasters certainly had some perspective that explosive development was possible. Let’s review their forecast discussion from Tuesday, October 24th. Senior hurricane specialist Richard Pasch wrote, “Sea surface temperatures are very warm, around 30 deg C, and the low-to mid-level humidities are fairly high.” He also went on to note that there was only weak to moderate wind shear over the system, which is also a favorable condition for intensification.


Read also

Scientists Don’t Know Why Otis Intensified to a Category 5 Hurricane so Quickly, Carrier Management / October 27, 2023

Nightmare’ Hurricanes Are Popping Up Out of Nowhere, Bloomberg / October 28, 2023


Pasch continued, “Steady strengthening seems likely until Otis makes landfall within the next day or so. Based on the current trends, the official intensity forecast is above most of the model guidance. The SHIPS Rapid Intensification (RI) indices show a greater than normal probability of RI, so some further upward adjustments to the intensity forecast are possible later today.” I have actually been impressed with how confidently NHC forecasters have been in mentioning rapid intesification. They certainly have plenty of practice in recent years.

After the storm, my former colleague and NASA research meteorologist Scott Braun said, “Conditions were present for rapid intensification, but it is hard to say at this time why the rate and magnitude of intensification were so great.” In the research community, Otis will be study for years to come. The models did not capture the level of intensification. Brian McNoldy is a hurricane expert at the University of Miami. His post below on the platform X is revealing.

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