polar trough

polar trough

[′pō·lər ′trȯf]
(meteorology)
In tropical meteorology, a wave trough in the circumpolar westerlies having sufficient amplitude to reach the tropics in the upper air; at the surface it is reflected as a trough in the tropical easterlies, but at moderate elevations it is characterized by westerly winds.
References in periodicals archive ?
There is an upper Polar trough to the north of the UK and that, coupled with the Jetstream virtually above us, means we are bringing in cold and wet Atlantic weather.