\n<\/p>\n
On Tuesday morning, few meteorologists were talking about Tropical Storm Otis.<\/p>\n
So what happened?<\/p>\n
One of the more remarkable things about Otis was that \u201cthis rapid intensification was completely unexpected,\u201d Tomer Burg, an atmospheric scientist, posted on X Tuesday evening<\/a> as it was starting to become clear how quickly the storm was strengthening.<\/p>\n The storm began to organize itself on Sunday morning, first as a tropical depression. At that time, forecast computer models didn\u2019t show much to be concerned about. Forecasters with the U.S. National Hurricane Center said that morning that \u201csome slight strengthening\u201d was possible over the following days. By Sunday evening, the computer forecast models were still not showing much.<\/p>\n A forecaster uses several tools to create a weather forecast, not just computer models. This is why meteorologists often preach that a computer model isn\u2019t a forecast \u2014 forecasters create forecasts, they like to say. They also use satellite data and climatological norms to help form their predictions. They use satellite images to help estimate expected wind speeds, and send hurricane hunter planes to the eye of a storm to collect real-time data.<\/p>\n Using some of those additional tools, forecasters had started predicting a stronger Otis than the models were suggesting \u2014 but they were still forecasting it to top out as a tropical storm.<\/p>\n By Monday afternoon, the models started indicating that the storm could become a hurricane, and forecasters believed that with the abundant amount of moisture in the area and warm ocean temperatures, the storm would strengthen gradually.<\/p>\n On Monday evening, with Otis still a tropical storm, satellite images revealed a little feature that could mean that the storm was about to intensify very quickly. But the models still weren\u2019t showing this, so forecasters continued to predict that the storm would be a weaker hurricane.<\/p>\n Global tools like the American forecast model and the European model haven\u2019t always been great about predicting storms\u2019 rapid intensification. Hurricane-specific models were created to help, and this year they have proved useful, including predicting the rapid intensification of Hurricane Idalia<\/a> well before that storm reached Florida, giving people in the state more time to prepare.<\/p>\n Despite the improvement in these models, sometimes, as with Otis, they don\u2019t forecast the increase in intensity, and we\u2019re left with a \u201cnightmare scenario,\u201d which Eric Blake, a forecaster with the National Hurricane Center, wrote in his discussion on Tuesday night as the storm approached southern Mexico and the intensity was becoming clear.<\/p>\n Later, in a post on X<\/a>, he said that he \u201cthought long and hard about the word nightmare.\u201d Ultimately, he decided that a storm growing from a tropical storm to a Category 5 hurricane headed toward a major city in less than a day fit that description.<\/p>\n Just to emphasize how poorly hurricane & global models performed for Hurricane Otis… here’s the intensity forecasts initialized 24 hours ago, with the dotted black line showing verification: pic.twitter.com\/DN5pf7lcOS<\/a><\/p>\n\n