Cyclonic precipitation is rainfall or snowfall associated with low-pressure weather systems (cyclones) where converging air masses are forced upward. It can affect large areas and persist for extended periods.
Cyclonic precipitation, also called convergence precipitation, is generated by large-scale low-pressure systems (cyclones) in which air masses converge and are forced upward due to the rotational dynamics of the storm system. In mid-latitude cyclones (extratropical cyclones), precipitation occurs along frontal boundaries where warm and cold air masses interact, as well as in the wrap-around region of the cyclone's center. Tropical cyclones (hurricanes and typhoons) produce some of the most intense and widespread precipitation events on Earth, with rainfall totals sometimes exceeding 500 mm in a single event. Cyclonic precipitation typically covers hundreds to thousands of square kilometers and can persist for several days as the storm system moves across the landscape. The precipitation type (rain, snow, sleet, or freezing rain) depends on the temperature profile of the atmosphere through which the precipitation falls. Cyclonic storms are responsible for a significant portion of annual precipitation in many regions, particularly in the mid-latitudes. These events are important for replenishing reservoirs, groundwater, and snowpack, but extreme cyclonic precipitation can cause widespread flooding, landslides, and erosion.