Outbreaks of rain will become persistent and heavy through Thursday afternoon, evening and night, before easing and clearing to the east by Friday morning. Heavy showers will follow for a time on Friday morning. Whilst this may fall as snow over hills, covered by a separate snow warning, rain accumulations of 20-40 mm are possible, with perhaps as much as 60 mm in a few places. This, combined with snow melt, may lead to some surface water flooding. For further details see https://www.metoffice.gov.uk/weather/warnings-and-advice/uk-warnings