I find the backyard West Branch responds more to rainfall rates, than overall total. Obviously, antecedent conditions are a big factor... but rainfall rates are what can really make it go nuts. There isn't nearly as much response as there is getting 3-4" in like 12 hours or less. No matter how dry it's been, if a lot of rain falls in a short period of time, the mountain runoff that feeds these waterways is substantial.