The Met Office forecasts that 134 areas across the UK will be drenched by rain on Wednesday as a “Spanish plume type of system” develops, described as “the UK’s most explosive weather phenomenon”.
The phenomenon occurs when warm air moving northward from Spain rises and cools, leading to the formation of thunder clouds. The Met Office explains: “As cooler air spreads from the west, instability increases and the very warm air rises through the cooler air, enhancing the formation of thunderstorms.”
Rain spreading north and east
In the morning, rain is concentrated mainly across the south and southwest of the UK, with a broad band extending eastward. At 10am, the heavier rain is especially concentrated around south Wales, southwest England and parts of the central/southern band.
This rain is expected to spread north throughout the day, with Manchester and Liverpool seeing rainfall by the afternoon. By the afternoon, the rain band appears to move generally northeast/east-northeast. Despite this, areas in Wales, northwest England and parts of the Midlands see the most persistent rain throughout the day.
Afternoon downpours and evening clearing
By 4pm, much of the Midlands will be covered by downpours, with deep blue filling much of the map in the region including Nottingham, Birmingham and Leicester. Southern England, particularly London and the southeast, appears to get increasingly dry after the early afternoon.
The band of rain continues to travel up, striking areas including Huddersfield and Harrogate around 7pm. The Met Office’s forecast for this period states: “Low pressure moving in from the southwest will bring an unsettled period, with heavy downpours and thunderstorms likely each day.”
“Turning increasingly humid, with temperatures staying a little above average.”
