Typhoons and Taiwan: When Track Errors Don't Matter

Did you know that the rainfall in Taiwan during typhoons is largely influenced by where the storm goes? Usually, the better a model predicts the storm's path, the better it can forecast how much rain will fall. But a recent study found that for typhoons moving in a specific way—from the southwest—this rule doesn't always apply. Researchers looked at five years of data from a special weather model that can track tiny cloud details. They found that for typhoons moving in from the southwest, even if the model didn't predict the path perfectly, it could still give a decent rainfall forecast. Why is that? Well, it turns out that when these typhoons pass near the northern part of Taiwan, a big weather pattern called the southwesterly flow is responsible for most of the rain. If the model can capture this flow well, it can still make a good rainfall prediction, even with some mistakes in the storm's path. But it's not always sunshine and rainbows. One example showed that when a typhoon moved across the southern part of Taiwan, the rainfall was more tied to the storm's own circulation. In this case, if the model didn't predict the path well, the rainfall forecast wasn't as accurate. So, it seems that for typhoons coming from the southwest, the quality of rainfall forecasts isn't just about how well the model predicts the path. There are other factors at play too.