Outflow boundary a downburst. "Gustnadoes", short-lived vertical circulations near ground level, can be spawned by outflow boundaries. Gust fronts create low-level wind shear which can be hazardous to planes when they takeoff or land. Flying insects are swept along by the prevailing winds. As such, fine line patterns within weather radar imagery, associated with converging winds, are dominated by insect returns. At the surface, clouds of dust can be raised by outflow boundaries. If squall lines form over arid regions, a duststorm known as a haboob can result from the high winds picking up dust in their wake from the desert floor.
Haboob silt and clay (collectively, dust) up from the desert, creating a wall of sediment that precedes the storm cloud. This wall of dust can be up to wide and several kilometers in elevation. At their strongest, haboob winds often travel at , and they may approach with little or no warning. Often rain does not appear at ground level as it evaporates in the hot, dry air (a phenomenon known as virga). The evaporation cools the rushing air even further and accelerates it. Occasionally, when the rain does persist, it can contain a considerable quantity of dust. Severe cases are