O se lee trough, ua lauiloa foi o se dynamic trough, o se "A pressure trough formed on the lee side of a mountain range in situations where the wind is blowing with a substantial component across the mountain ridge; often seen on United States weather maps east of the Rocky Mountains, and sometimes east of the Appalachians, where it is less pronounced". E mafai ona fausia pe o se taunuuga o le adiabatic compression of sinking air on the lee side of a mountain range, or through cyclogenesis resulting from "the horizontal convergence associated with vertical stretching of air columns passing over the ridge and descending the lee slope". Fesili: E mafai faapefea ona fausia se lee trough?
pe o se taunuuga o le compression adiabatic o sinking ea i le itu lee o se atumauga, po o le ala i cyclogenesis e mafua mai i "le faalava convergence fesootai ma faalauteleina tūsaʻo o pou ea e ui atu i luga o le tumutumu ma le alu ifo i le malifa lee