To generate an initial state for the prognostic model, a diagnostic model (Kunz, R., 1991) is applied using measured temperature and wind data. Both data can be provided as:
* surface measurements i.e. single measurements directly above the surface (not necessary)
* upper air soundings (i.e., soundings that consist of two or more  measurements at different heights) at a constant geographical location is required (with at least one sounding for temperature and wind velocity).