What is indicated by a "PROB" in a TAF?

In a Terminal Aerodrome Forecast (TAF), the term "PROB" stands for "probability" and is used to indicate the likelihood of a specific weather event occurring within the forecast period. The use of "PROB" is followed by a percentage, typically indicating the probability range (e.g., 30 or 40 percent) of that event happening. This helps pilots and other aviation professionals gauge the potential for weather phenomena, such as thunderstorms or significant changes in visibility, thus aiding in flight planning and safety decisions.

In contrast, the other options do not correctly represent the meaning of "PROB" in the TAF context. The remaining ideas pertain to different aviation terminologies or concepts that are not related to the probability of a weather event.