A gust front is the leading edge of the cold air mass spreading along the surface from the base of a thunderstorm, produced by downdrafts and downbursts. It acts as a small-scale cold front: upon arrival, one experiences an abrupt wind shift (gusts that can exceed 80 km/h), a sudden temperature drop of 5–10 °C within minutes, a pressure rise, and frequently dust or sand raised by the wind. The gust front can propagate tens of kilometres ahead of its parent storm, heralding its arrival well before the rain arrives. In desert and semi-arid environments, it can raise spectacular dust storms called haboobs. Most importantly from a meteorological standpoint, the gust front can act as a triggering mechanism for new storms: by pushing warm air upward along its edge, it can initiate new convective cells, generating self-renewing storm chains. On Doppler radar, the gust front is identified as a thin convergence band in the radial velocity field or as a thin line of weak echoes (fine line) in reflectivity. Its detection is essential for nowcasting severe phenomena and for the safety of takeoff and landing operations at airports.