Rain prediction alarm

I’m currently working on a new plugin. A rain prediction alarm. The amount of minutes ahead and a amount of rain threshold can be configured. I use it to close my sunscreens 5 minutes before it starts to rain. Plugin is in final testing stage.

My problem is which ‘base’ device to use. Now the plugin is based on a motion sensor and sets the tripped variable if rain is expected. I have looked at the rain sensor, but because a prediction is something else than actual rail this doesn’t look natural for me. Any suggestions?