FAA Commercial Pilot Airplane (CAX)WeatherEasy
A pilot receives a Terminal Aerodrome Forecast (TAF) for their destination airport, which includes the code 'PROB30 1518/1522 TSRA'. What does this portion of the TAF indicate?
- AThere is a 30% probability of thunderstorms with rain occurring between 1500Z and 2200Z on the 15th of the month.
- BA 30% chance of isolated thunderstorms with heavy rain is expected to develop between 1800Z and 2200Z.
- CThere is a 30% probability of light thunderstorms with rain occurring between 1500Z and 1800Z, and again between 1500Z and 2200Z.
- DThunderstorms with rain are expected to begin at 1500Z and end at 2200Z with a 30% chance of severity.
Show answer & explanationAnswer & explanation
Correct answer: A. There is a 30% probability of thunderstorms with rain occurring between 1500Z and 2200Z on the 15th of the month.
The 'PROB30' indicates a 30% probability. The '1518/1522' indicates the period of the 15th day of the month from 1800Z to 2200Z. 'TSRA' stands for thunderstorms with rain.
Why the other options are wrong
- B. Misinterprets the start time and the meaning of 'isolated' or 'heavy'.
- C. Incorrect interpretation of the time period and the recurrence of the event.
- D. Incorrectly interprets 'PROB30' as severity and misreads the time period.
TAF PROB30
In a Terminal Aerodrome Forecast (TAF), 'PROB30' indicates a 30% probability of the described weather occurring during the specified time period.
- PROB30 indicates a low probability (30%)
- PROB40 indicates a moderate probability (40%)
- The time period is given as DDHH/DDHH, where DD is the day and HH is the hour (UTC).
Memory trick: Probability's Time, Type, and Truth, from a TAF's weather youth.