It's not that, it's purely statistical based on how rare double digit snowstorms are in a hostile pattern. And where I live double digit snowstorms no longer happen in March. I would say that from now until the end of the season the chance of a 10 inch snowstorm are less than 10 percent. 6 inches? Maybe 25 percent
4-6 inch storms are a different beast altogether and can happen in any pattern. It's why I specifically referred to double digit snowstorms as being extremely unlikely, not the smaller ones.