a personality trait of, type of behavior in which one represents themselves as being "down with the dirty south".
Usually identifiable by a certain swagger, or self confidence , which exemplifies being down with the south and proud of it, and not particularly fond of Northern culture/ way of life. People with southernly flow usually express them selves with the way they dress and talk and generally have interests in things that one might call southern. This is not to be confused with redneck in anyway, A redneck could have southernly flow or not, even a highly educated individual such as a doctor could posses southernly flow, southernly flow is commonly shown off by ninjas, overall having southernly flow is closely related to southern hospitality but has more to do with how a person carries themselves with that hospitality. Overall dudes it just means your down with the south and like it. This also could just mean you have a stinky futon laying around somewhere and you go to class with bed head and stuff.
"Yo man look at that dude brah with the southernly flow, the bro means straight business."
"Hey man I see you keepin it real with that Southernly flow of yours"
"Man that kids got so much southernly flow a hippo would not even think of messin with him, but damn all them hoes sure do."
Dude ! that chick is bangin man definitely got that southernly flow goin on.
"Na man your not down with the South you ain't got no Southernly flow about you man."