Meteorological Administration promotes Township Forecast 2.0, combining AI and manual judgment to improve severe weather warnings

Afternoon thundershowers can come at any time. Where, how much, and how long they will fall is one of the most unpredictable weather conditions. Behind an official rainfall forecast map from the Central Meteorological Administration is not a computer model that calculates the answer, but a forecaster who has to make judgments from a large number of global, regional, ensemble and AI models. Ye Shixuan, director of typhoon and severe weather forecast technology at the Forecast Center of the Meteorological Administration, said that the Meteorological Administration has launched the "Township Forecast 2.0" service and will gradually develop township-scale disastrous weather warnings and strengthen real-time warnings for severe weather such as thunderstorms, hail, strong gusts, tornadoes and squall lines.

The Meteorological Administration holds a meteorological practice workshop. Ye Shixuan said that the current 6-hour and 12-hour quantitative precipitation forecasts can see the next 48 hours. During large-scale and severe heavy rains, the 3-hour quantitative precipitation real-time forecast can see the next 12 hours.

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People often hear about European and American models, which are mainly global forecast systems with a resolution of about 10 to 20 kilometers. The advantage is that they can grasp the weather trends for the next week or even longer. However, to accurately predict where and how much rain will fall, we still need to rely on regional models with a resolution of 1 to 3 kilometers and ensemble forecasts with a resolution of 2 to 3 kilometers.

AI is not omnipotent. Ye Shixuan said that AI models can use less computing resources to quickly forecast for longer periods of time, but the current resolution is about 25 kilometers, and rainfall forecasts are relatively smooth. You can refer to the shape and trend of rain areas. Fine rainfall still requires the assistance of high-resolution models.

Forecasters will not only look at the latest model results, but will also compare the changes in the same model from old to new, as well as the differences between different models, and then manually adjust the official forecast. Ye Shixuan bluntly said that this is the value of the existence of forecasters. "It is not just about looking at the data, but how to publish the data." Human judgment is still required.

Uncertainty in typhoon tracks, in particular, will directly affect rainfall forecasts. Ye Shixuan said that the atmosphere has chaotic characteristics, and the results may be significantly different after a few days if the initial conditions are slightly different. Therefore, ensemble forecasts are used to generate a variety of possible scenarios to help forecasters grasp risks.

The closer to rainfall, the more important radar is. The Meteorological Department uses radar to grasp the current rainfall, and uses a large amount of radar and model data to strengthen short-latency heavy rainfall forecasts in the next few hours. In the future, it plans to build a Jinma radar to expand the radar monitoring range and improve early cloud and fog monitoring capabilities.

The forecast will also move from "what will the weather be like" to "what will be the impact of the weather". Ye Shixuan said that for example, instead of just informing that the daily rainfall may reach 200 mm, in the future, we hope to provide further risk information such as whether the urban area may be flooded and whether the roads may be closed, so that the people and disaster prevention units can more easily decide what to do next.