I don’t know about the A part of AGW, but I suspect this very large weather system is cause by warmer than usual Pacific Ocean temperatures putting more moisture into the atmosphere. As I said, don’t know if caused by sun or people, but it is happening.
Happens every few years. Nothing really unusual about it. In fact, “normal” weather is nothing more than the mathematical average of above normal and below normal conditions...which are common. “Normal” conditions are actually quite rare.
A = Anthropogenic = man-made.