downrush

A downrush is a meteorological phenomenon characterized by a sudden and intense downward surge of air. This event is typically associated with strong convective thunderstorms, particularly in the mature or dissipating stages. Downrushes are driven by the cooling of air within the thunderstorm cloud. As rain, hail, and ice fall, they cool the surrounding air through evaporation and melting. This colder, denser air then sinks rapidly towards the ground.

Upon reaching the surface, the downrush spreads out horizontally, creating a gust front. This gust front can manifest as a sudden increase in wind speed, often accompanied by a drop in temperature and a shift in wind direction. Downrushes are responsible for many of the damaging straight-line winds associated with thunderstorms, distinct from tornado-force winds which are rotational. They can cause significant damage to trees, structures, and other objects in their path. Observing a downrush often precedes or accompanies heavy precipitation. The force of a downrush is a result of the momentum transfer from the descending air to the surface.