How is a trowal depicted on a GFA?

A trowal, or tropopause frontal wave, refers to a specific weather phenomenon often associated with upper-level fronts that can lead to significant weather changes. On a Graphical Flight Information (GFA) chart, a trowal is depicted using the symbol for both cold and warm fronts, resembling a zipper. This representation helps pilots identify the areas where these fronts interact, indicating potential weather conditions such as instability and precipitation that can affect flight safety.

The depiction as a zipper of cold and warm fronts effectively communicates the complexity and unique characteristics of the trowal since it combines the features of both types of fronts. Each part of the zipper symbolizes changes in temperature and wind direction, which are critical for pilots to understand the possible impacts on their flight paths. Therefore, recognizing this specific graphical representation allows pilots to assess potential weather risks accurately.