Which product would be used to forecast an isolated severe thunderstorm 25 miles west of Tallahassee, FL (TLH)?

The use of a Convective SIGMET is appropriate in forecasting isolated severe thunderstorms because it is specifically designed to provide information about significant convective activity, such as severe thunderstorms, tornadoes, and other weather phenomena that could impact aviation safety. Convective SIGMETs are issued for areas experiencing or expected to experience severe turbulence, large hail, or wind gusts in excess of 50 knots due to thunderstorms.

In the context of your question, since there is an isolated severe thunderstorm occurring 25 miles west of Tallahassee, a Convective SIGMET would provide essential and timely information regarding the storm's severity and potential hazards. This allows pilots and flight planners to make informed decisions about flight safety and route planning in relation to the thunderstorm.

In contrast, the other options serve different purposes. For instance, an Area Forecast offers a broader overview of weather conditions over larger geographic areas, while a Terminal Aerodrome Forecast concentrates on weather specific to airports, and an Aviation Weather Warning alerts to hazardous weather conditions but is more general than a Convective SIGMET. Therefore, the Convective SIGMET is the most targeted and relevant product for forecasting isolated severe thunderstorms.