If the forecast on your phone has a 20% chance of measurable snow, most people just assume that it isn't going to snow because the probability is so low. This means that given an infinite number of similar cases, measurable snow would be expected about one out of five times on average. If your phone has a 20% chance of measurable snow for five consecutive days, the odds each day are one in five; but at the end of five days, it might have snowed on two or three days or not at all, because the probabilities are based on an infinite number of cases.
The latest probabilistic flood forecast has a 50% chance of the Red reaching 35.9 feet in Fargo, which is quite manageable, but only a 5% chance of 40.6 feet, which would be similar to 2009. Both possibilities are in play, as well as a spectrum of other results depending on future weather. At this point, it's a matter of probabilities.