Insights from Nowcasting and Mesoscale Research Working Group Projects of the World Weather Research Programme

Insights from Forecast Demonstration Projects and Research Development Projects, training workshops and symposia, conducted between 2000 and 2024 are summarized. The projects were organized by the Nowcasting and Mesoscale Research Working Group of the World Weather Research Program of the World Meteorological Organization. The objective was to advance, promote and build capacity in nowcasting and very short-range forecasting. The projects were associated with the Olympic Games, emergency management and aviation services. They brought international experts together to work in a collaborative fashion. Extensive interaction with end-users and decision-makers expanded and extended the scope of services from traditional weather hazards (heavy rain, wind, hail, lightning) to include specific user needs (e.g., visibility in complex terrain or airport runways, periods of calm winds or light rain, heat stress). Substantial progress has been made in many areas including: advanced radar nowcasting algorithms, stochastic nowcasts, kilometric and hectometric numerical weather prediction models; blending of observations and models and multi-model systems. Verification was a key and valuable component of the projects quantifying the results. Also, the types of services have expanded to include both summer and winter services, complex terrain and urban environments, air transport, air quality, hydrology and health. Insights are presented in all aspects of nowcasting and very short-range forecasting from end-user decision-making, critical role of the forecaster, forecast systems (models, heuristics, observations), to science and knowledge gaps.