Thanks for reaching out. We are reading the observed rainfall from the past 24 hours and the predicted rainfall for the next 24 hours, but in addition we are also taking ET data from the last time your Iro ran and looking into the next time your Iro will run as well and based of that available data we are skipping according to your threshold. So in this case you received enough rainfall recently to skip, meaning there was not enough lost to ET to warrant a watering.
Our new flex schedules will take this approach as well but more on a daily basis.
If you have anymore questions let us know.