A band of rain is likely to reach southwest England on Thursday afternoon then spread quickly northeast across the rest of the warning area by evening. The rain is only likely to last for a few hours in any one location but will be heavy at times. A further 10 to 20 mm is likely quite widely, and in the wetter spots, particularly across the moors, a further 20 to 40 mm is possible and will fall onto already saturated ground. For further details see https://www.metoffice.gov.uk/weather/warnings-and-advice/uk-warnings