Definition
In aviation weather reports (METAR) and forecasts (TAF), TS is the contraction used to indicate a thunderstorm — a localized storm produced by a cumulonimbus cloud, accompanied by lightning and thunder, and often associated with heavy precipitation, strong gusty winds, turbulence, hail, and wind shear. TS is reported in the present weather group of a METAR and may be combined with other descriptors (for example, TSRA for thunderstorm with rain, +TSRA for heavy thunderstorm with rain).
Plain English
TS is the short code for thunderstorm. When you see it in a weather report, it means a thunderstorm is happening at or near the airport.
Context Anchor
Seen in aviation weather reports and forecasts, especially in the present-weather part of a report.
Why Pilots Care
Thunderstorms can produce extreme turbulence, icing, and wind shear that endanger aircraft and require pilots to deviate or delay flights.
Grounding Statement
When you see TS, picture an active storm cloud with thunder and lightning, not just ordinary rain.
Intuition Check
Do not read TS as just “bad weather.” It specifically means thunderstorm activity; any rain, snow, or hail is shown by added weather codes.
Example Sentence 1
The METAR showed TSRA, so the pilot delayed departure until the thunderstorm and rain had passed.
Example Sentence 2
Controllers advised rerouting to avoid the area of TS reported along our route.