Not quite. When there has been a storm at sea, the after-effect of the storm is to produce very large swells in the water [which in a small context are ripples]. These swells will, when hitting land, become large waves.
In the context of a post-political debate, the afterswell will be the reactions in those listening to or reading about the debate = the way in which their opinions will grow or change in such a way as to change public thinking/opinion.