If you cross the county line—less than 3-ish miles from where i work, a little farther from where i live—we have that same magical line. if it snows, it usually stops right there. Same thing with rain, course that can go either way.
in the summer we have prevailing winds off the ocean. it can make for some hellacious aft thunderboomers! The runways at cherry point mcas draw storms like a magbet.
I was stationed at Cherry Point in my USMC days. And as a very young boy we lived for about 3 years on the coast in a very small town called Swansboro.