Valley exit jet

A valley exit jet is a strong, down-valley, elevated air current that emerges above the intersection of the valley and its adjacent plain. These winds frequently reach a maximum of 20 m/s (45 mph) at a height of 40–200 m (130–660 ft) above the ground. Surface winds below the jet may sway vegetation but are significantly weaker. A valley exit jet is a strong, down-valley, elevated air current that emerges above the intersection of the valley and its adjacent plain. These winds frequently reach a maximum of 20 m/s (45 mph) at a height of 40–200 m (130–660 ft) above the ground. Surface winds below the jet may sway vegetation but are significantly weaker. The presence of these strong nighttime down-valley air flows has been documented at the mouth of many Alpine valleys that merge with basins, such as the Inn Valley of Austria, where the jet is strong enough to be heard at the ground. In the United States, exit jet signatures have been observed at the North Fork Gunnison River at Paonia, Colorado; the exit of South Boulder Creek south of Boulder, Colorado; Albuquerque, New Mexico at the mouth of Tijeras Canyon; and the mouth of Spanish Fork Canyon in Utah.