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.

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.

Hurricane specialist Eric Blake echoed this thought on the same thread. He wrote, “Every operational model missed it before the RI occurred and the EC was the best of the sad bunch, which is saying something because usually it has no intensity skill.” Though gains have been made, it has long been known that skill with hurricane track forecasts have outpaced intensity forecasts. I have written on this very topic previously in Forbes. Hurricane track is governed by larger scale atmospheric processes that can be sufficiently resolved in the models. Intensity changes are related to smaller scale features of the ocean heat content, wind shear, and energy exchanges within the eyewall structure. Many of these processes are often difficult to resolve in our models. A 2022 NOAA report argued, “Improving NOAA’s hurricane intensity forecasts will require closing gaps in ocean and air-sea observations, as these data are key to better understanding the interaction processes that lead to the formation and intensification of storm systems.”

Speaking of track, the forecasts certainly indicated that Acapulco would be dealing with some type of storm albeit a much weaker system. Forecasters knew that a tropical storm, at a minimul, would likely impact the region but as weather expert Tomer Burg remarks, it was certainly unexpected be a Category 5. We just do not expect this level of intensity in East Pacific hurricanes near the coast of Mexico.

The damage was extensive but was primarily wind-related. The region is not accustomed to Category 5 storms, but this could be a harbinger of things to come. It is also a reminder that infrastructure of the future will have to be adapted to our new hurricane realities. Ironically, many people have asked why there was not more storm surge damage. Dr. Jeff Masters explains that the elevation and deep water profile offshore were not conducive for the level of storm surge one might expect from a Category 5 storm.

Ultimately, I think the lesson from Otis may be to prepare for the worst if a tropical storm or hurricane is headed your way. The looming challenge of rapid (and hyper) intensification will be with us. Resist normaly or recency biases. They do not prepare you for a storm that you have not expertienced before.

Denial of responsibility! TechCodex is an automatic aggregator of the all world’s media. In each content, the hyperlink to the primary source is specified. All trademarks belong to their rightful owners, and all materials to their authors. For any complaint, please reach us at – [email protected]. We will take necessary action within 24 hours.