What does 'TS' signify in METAR reporting?

In METAR reporting, 'TS' signifies Thunderstorm. This abbreviation is used to indicate the presence of thunderstorms in the area, which is critical information for pilots and meteorologists. Thunderstorms can have significant impacts on aviation, including turbulence, lightning, and severe weather conditions. It's important to note that the use of 'TS' helps in quickly communicating weather conditions without needing lengthy descriptions, thereby enhancing safety and operational efficiency during flight operations. The other options represent different weather phenomena that have their own specific abbreviations; however, none denote thunderstorms.