Did you look at the pics we posted? Those are what ribbon snakes typically look like (the one I posted was the orang-est pic I could find). The stripes are 'bold' (though that is qualitative anyways) and the color is typically yellow, though I'm sure there is some variation as there is with most species. At any rate, I'd side with what is common and geographically possible over the scant reliability of briefly seeing some snake flee for cover.