Forecasting systems calculate future atmospheric conditions on the basis of measurement data and observations. MeteoSwiss uses these weather models to create weather forecasts and to enable it to issue weather warnings in the event of imminent hazards.
Every weather forecast and warning is based on a complex process chain. A myriad of data collected from measurements and observations is processed and fed into the deployed weather models.
The weather is based on complex physical processes in the atmosphere. These can be approximately described using mathematical equations. To forecast the following day's weather, these equations have to be calculated. For a numerical forecasting model, a grid is applied to the globe or certain parts of the Earth at different altitudes within the atmosphere. At each grid intersection, a set of formulas is applied to calculate the development of various weather parameters, including temperature, air pressure, humidity and wind. Data measured from this point is incorporated as an input value. On this basis, the computer calculates how the atmosphere may change in future.
Meteorologists analyse the results of various weather models. They know their strengths and weaknesses and can accurately assess them. To interpret the models, the forecasts are compared with current measurement values. Images produced by satellites, weather radars and webcams across Switzerland are also assessed. This provides an accurate picture of the current weather situation. Based on this wealth of information and using their experience, meteorologists finally formulate the forecast.
The forecasting systems are also used to ensure the early identification of potential dangers. They thus contribute to protecting the population against natural hazards. MeteoSwiss issues warnings in the event of extreme weather such as heavy precipitation, major snowfalls or storms. In this area, MeteoSwiss works closely with other institutions such as the Federal Office for the Environment, the Federal Institute of Snow and Avalanche Research and the National Emergency Operations Centre. The models also allow the forecasting of the dispersal of substances carried in the air such as volcanic ash or radioactive particles, and for possible warnings to be issued.