Terms of Probability

From reader John at Marc Ambinder's blog at The Atlantic:

Q: What's the difference between isolated and scattered thunderstorms?

A: The National Weather Service expresses the probability of 
measurable precipitation (0.01 inch) for a given location using 
percentages and terms such as isolated and scattered. Isolated means a 
chance of precipitation of less than 30% and scattered is used for a 
30% to 50% chance. Likely describes a probability of 60 percent or 
greater.