Errors or bugs
@zoomarch Weather models are not always 100% accurate. Also, for things like thunderstorms, weather models can not sometimes keep track of the speed the storm moves. The ICON model would be slightly better than the model you were using cause it has much better resolution.
GFS is a low resolution model (22 km).
For better forecasts in "our" area (Mediterranean)
I prefer ECMWF (res. 9 km) and ICON (res. 7km).