A stream of air moving northward from the Gulf of Mexico, generally lower in altitude (~ 2 km or 1.3 miles) than the jet stream. Wind speeds are lower than the polar jet stream, and the low level jet generally transports significant moisture from the gulf into the central and northern United States.

A relatively fast-moving (20 to 60 miles per hour) layer of air that forms 1,000 to 3,000 feet above the surface. The low-level jet is a summertime nocturnal event, forming above the nighttime inversion as the air near the surface cools bringing low-level stratus clouds (late night and morning low clouds) to south-central Texas. It is also associated with flow off the Gulf of Mexico during spring through fall, bringing moisture rapidly back into Texas and the Plains as high pressure systems move eastward behind departing cold fronts. This low-level jet provides much of the moisture needed for thunderstorm development in this area.

(abbreviated LLJ) - a region of relatively strong winds in the lower part of the atmosphere. Specifically, it often refers to a southerly wind maximum in the boundary layer, common over the Plains states at night during the warm season (spring and summer).