precipitation nowcasting

 Weather forecasting has improved markedly at predicting the weather days and even weeks ahead, relying on the analysis of a mass of data about the movements of fluids in the atmosphere. It is not, however, good at the very short-term forecast. What is going to happen in the next couple of hours and do I need to take an umbrella?

 Precipitation (that is, rain) nowcasting collects data on what is happening now by firing a radar beam into the lower atmosphere and measuring the relative speed of the signal, that speed being slowed by water vapour.  Using artificial intelligence and machine learning, the forecasters can quickly make probabilistic predictions based on the past 20 minutes of data gathering as to what will happen in the next 90 minutes.  This has benefits for transport and agriculture as well as for the individual who doesn’t want to be caught in a sudden downpour.