upper-level trough

upper-level trough

[¦əp·ər ¦lev·əl ′trȯf]
(meteorology)
A pressure trough existing in the upper air, but sometimes restricted to the troughs that are much more pronounced aloft than near the earth's surface. Also known as high-level trough; trough aloft; upper trough.
References in periodicals archive ?
The occurrence of western Iran heavy rain is related to existence STJ in based on upper-level trough which is propagated to Western Iran located above surface cyclone with extending pressure trough to western Iran and North Arabia Saudi [7].
We're under the influence of an upper-level trough pattern, and that's keeping the onshore flow and precipitation right here," said Metcalf.
After one of the warmest autumns on record in the Mojave Desert, a drastic shift in the upper air pattern took place in mid-December 2008 as a deep, upper-level trough established itself across the western United States.