What Kind of Snake is Grey with a White Strip?
You can't be positive if you don't have anything to identify it
with, but one snake that comes to my mind is a Garter Snake. They
are usually dark in color with at least two white stripes going
along its back. If this doesn't describe the snake that you saw, I
suggest going to google (see related link). Then you can look at
pictures whatever you type in. try looking for your snake.