Explain the difference between forecast verification and forecast skill.

• A. Verification measures how forecasts compare to actual outcomes; skill assesses forecast quality relative to a reference such as climatology or persistence.
• B. Verification and skill are identical; both compare forecasts to past weather.
• C. Verification is only used for temperature forecasts; skill is used for precipitation.
• D. Verification evaluates model physics; skill evaluates computational speed.

Answer: (A)

Forecast verification is the process of comparing forecasted weather to what actually happened, using observations as the ground truth. It tells you how well the forecast matched reality in an absolute sense—often summarized with metrics of accuracy, calibration, and reliability.

Forecast skill measures how good the forecast is relative to a simple reference forecast, such as climatology (the long-term average for that time and place) or persistence (assuming tomorrow will resemble today). Skill is about added value: a positive skill score means the forecast beats the reference; a zero or negative score means it is no better than, or worse than, the baseline.

So verification answers “how well did forecasts match reality?” while skill answers “does this forecast provide more predictive value than a simple, baseline forecast?”