It's all about the evaporation:
“We are in part responsible for what’s going on in the context of fossil fuel combustion emissions that are leading to global warming. The ocean is a huge reservoir that is absorbing heat and seeing more evaporation. With more evaporation comes more rainfall.”
I've lost count of how many times I've had this conversation with people over the last year or two. But it's really a relatively simple concept/formula. Heat leads to evaporation leads to precipitation. Yes, silt and debris form choke points in our streams/rivers, and the water has to go somewhere. Yes, poor landscaping and over-development cause stormwater runoff. But the main driver of flooding is increased water vapor in the air. So the next time you're trying to explain to the dubious how climate change is causing this, don't waste time with stuff like "changing weather patterns" or other obscure references, just remember that formula above.