What does the term PROB40 2102+TSRA indicate in a Terminal Aerodrome Forecast (TAF)?

The term PROB40 2102+TSRA in a Terminal Aerodrome Forecast (TAF) indicates probabilities of specific weather conditions occurring within a defined timeframe. The "PROB40" signifies a 40 percent probability of the forecasted weather conditions happening, which are specified immediately following this term.

In this case, "2102+" indicates that there is a forecasted timeframe starting at 2100 Zulu (Z) and extending beyond that, and "TSRA" stands for thunderstorms with rain. Thus, the interpretation is that there is a 40 percent chance that thunderstorms and rain will occur between 2100Z and 0200Z. This specificity is critical for pilots and aviation personnel in making informed decisions regarding flight operations based on the likelihood of adverse weather conditions.

The other options do not accurately represent the meaning of the term in a TAF format. For example, there isn’t any mention of clear skies, tornado activity, or wind chances in the context of the given forecast, highlighting the importance of understanding specific meteorological terminology for aviation safety and operational planning.