In this space we often write about the do's and don'ts of probability assessment and working with uncertainty in general. One of the most fundamental don'ts is that you should not use words to define probabilities. You should more than avoid it, you should never do it. A 15% chance of something happening is exactly that: a 15% chance. Write it as 0.15 if you like, but don't call it a "moderate risk" or say it "probably won't happen".