I have a theory. The problem may come from the fact that the moisture graph is capped at 0%-110%. In all reality, 0% really means 50% with my allowed depletion of 50%. The moisture level can actually go below 0%. If it did, the sum of precipitation+forecast+irrigation-evapotranspiration would provide a more accurate look at the state of the soil. It would allow waterings even if rain is predicted, because it would take more water to reach a level in the top 50% allowed depletion of mine. The fact that 0% is the bottom and no further water depletion is possible, allows small amounts of rain to skip the watering, even when the soil is in dire need of water.
