Weather forecasts are not always accurate. They are based on a weather forecaster's judgment on what is most likely to happen given a number of potential scenarios. Each scenario, in turn, is based on a prediction on what may happen if certain conditions occur. But conditions almost always change in unexpected ways. Which of the following statements best expresses the main conclusion of the above argument?

A. Weather forecasts are based on a number of potential scenarios.
B. Weather forecasts are not always correct.
C. Conditions almost always change in unexpected ways.