EntityQ2454987· pop 31· linked from 1,024 articlestroughSign in to saveelongated region of low atmospheric pressureConnectionstropical waveEntityPhilippinesCountrytropical cycloneEntityvalleyEntityNorthern HemisphereEntityWayback MachineEntitycycloneEntityatmospheric pressureEntityadiabatic processEntityweather frontEntitycontour lineEntityjet streamEntitytopographic mapEntitylow pressure areaEntitywesterliesEntityNational Weather ServiceEntitySouth ChinaEntityRossby waveEntityvorticityEntitymountain saddleEntityCategoriesAtmospheric circulationAtmospheric dynamicsSynoptic meteorology and weather