Sándor Baran

1 INTRODUCTION The advent of ensemble forecasting systems represented a major breakthrough in meteorology, fundamentally changing the way weather predictions are generated and interpreted. Unlike traditional single-run deterministic models, which produced a single outcome based on fixed initial conditions and often overlooked atmospheric uncertainties, ensemble systems introduced a transformative approach.

1 INTRODUCTION For more than 30 years, ensemble forecasting was been established as a discipline in numerical weather prediction (Lewis, 2005). Ensembles are required to generate useful probabilistic weather forecasts that capture situation-dependent forecast uncertainties (Leutbecher & Palmer, 2008). Users of ensemble forecasts and developers working on ensemble prediction methodologies require metrics, known as scores, that assess how “good” the ensemble forecasts are.

1 INTRODUCTION Due to its significant impact on a wide range of aspects of aeronautical meteorology, visibility is a critical parameter for weather forecasters and pilots. Visibility can be reduced because of snow, rain, haze, and fog; the latter is reported “when visibility is reduced by water droplets to less than 1000 m” (WMO, 2022).