Low Level Jet

(abbrev. 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).

The term also may be used to describe a narrow zone of strong winds above the boundary layer, but in this sense the more proper term would be low-level jet stream.

A regular, strong, nighttime, northward flow of maritime tropical air over the sloping Great Plains of the central United States. The wind increases to a peak in the lowest kilometer and then decreases above.