@Vela77
There is a workaround to open Windy with your preferred model.
First choose the model and layer you want to set as default. Then in Settings -> Start-up location and layer -> Start-up layer -> Use last overlay.
It works if you don’t start Windy with the widget and if you still have the same layer and model displayed when you quit the app. Otherwise the last overlay is considered as new default for next time.