Which of the following features is depicted by a 20kt Change in Jetstream wind Speed on a SIGWX chart?

• A. Severe Aircraft Icing
• B. 20kt Change in Jetstream wind Speed
• C. Tropopause LEVEL
• D. Surface Cold Front

Answer: (B)

Jet stream wind speed changes are a key upper-level feature on SIGWX charts because they highlight wind shear in the jet, which can impact aircraft performance and turbulence risk. A 20-knot change in jetstream wind speed is shown to mark where the jet’s wind speed increases or decreases by 20 knots over a short distance, drawing attention to possible turbulence and planning concerns along flight routes. This depiction directly communicates the specific wind-speed variation in the jet stream, making it the best choice for what that symbol represents.

Other options describe different phenomena or surface features that aren’t represented by a 20-knot change in jetstream wind speed. Severe icing has its own symbols and conditions, tropopause level isn’t indicated as a standalone marker on SIGWX in this context, and a surface cold front is a surface feature more typically shown on surface weather charts rather than as an upper-level jet-stream wind-speed change.