sentences:  The UK Met Office suggested that the influx of accentors was driven by strong and persistent easterly winds from Siberia, partially driven by a high-pressure area centred over Scandinavia.Another weather system produced easterlies in western Asia during the same period.The weather conditions that carried the accentors so far west also brought large numbers of other Siberian migrants, including a record arrival of yellow-browed warblers in northwest Europe and a sprinkling of extreme eastern rarities such as the UK's first pale-legged leaf warbler and the Netherlands' second eastern crowned warbler.