Why Hurricane Otis took many by surprise | ET REALITY


One of the most notable things about Otis was that “this rapid intensification was completely unexpected,” said Tomer Burg, an atmospheric scientist. published on Tuesday evening as it was beginning to become clear how quickly the storm was strengthening.

The storm began organizing Sunday morning, first as a tropical depression. At the time, computer forecasting models didn’t show much to worry about. Forecasters at the U.S. National Hurricane Center said that morning that “some slight strengthening” was possible in the coming days. As of Sunday afternoon, computer forecast models still weren’t showing much.

A forecaster uses several tools to create a weather forecast, not just computer models. This is why meteorologists often preach that a computer model is not a forecast: they like to say that meteorologists create forecasts. They also use satellite data and weather standards to help make their predictions. They use satellite images to help estimate expected wind speeds and send hurricane hunter planes into the eye of a storm to collect real-time data.

Using some of those additional tools, forecasters had begun to predict a stronger Otis than models suggested, but still predicted it would peak as a tropical storm.

On Monday afternoon, models began to indicate that the storm could become a hurricane, and forecasters believed that with abundant moisture in the area and warm ocean temperatures, the storm would gradually strengthen.

On Monday night, when Otis was still a tropical storm, satellite images revealed a small feature that could mean the storm was about to intensify very quickly. But the models did not yet show this, so forecasters continued to predict the storm would be a weaker hurricane.

Global tools like the US forecast model and the European model have not always been great at predicting rapid intensification of storms. Specific hurricane models were created to help, and this year they have proven useful, including predicting the rapid intensification of Hurricane Idalia long before the storm reached Florida, giving people in the state more time to prepare.

Despite the improvement in these models, sometimes, as with Otis, they do not predict the increase in intensity, and we are left with a “nightmare scenario,” as Eric Blake, a forecaster at the National Hurricane Center, wrote in his discussion Tuesday night as the storm approached southern Mexico and the intensity became clear.

Later, in a post on X, said he “thought a lot about the word nightmare.” In the end, she decided that a storm that upgraded from a tropical storm to a Category 5 hurricane and was headed toward a major city in less than a day fit that description.

Even when Otis was still a tropical storm, there was enough evidence for Mexico’s government to issue a hurricane warning for the coast, and hurricane forecasters were still expecting a stronger storm than computer models were predicting.

On Tuesday afternoon, a hurricane hunter plane passed through the eye of the storm and found that its intensity was much greater than satellite estimates suggested.

On Tuesday night, with the storm clearly approaching Acapulco, the hurricane center issued a rare special discussion on advisory forecasts. “The rapid intensification observed today has continued,” the forecasters wrote. “The environment is not expected to change much before landfall, and there are no signs of this explosive intensification stopping.”

It was a powerful warning to everyone in the path of the storm that this storm would be much larger and stronger than had been expected even a day earlier.

By Wednesday morning, Otis had made landfall as a Category 5 hurricane, leaving many wondering about the fate of Acapulco and also why forecast models had failed to predict the future.

Over the next few days and weeks, scientists will focus on answering that question.

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