An area of low pressure is set to develop in France as cool air high in the atmosphere pushes over very warm and moist air near the surface.
This combination makes the atmosphere unstable with air rising upwards to form thunderstorms. These storms will initially develop in France before heading northwards across the UK.
The heaviest rain is likely to affect central southern England, south-east England and the Midlands on Friday night before moving to northern England and Scotland by Saturday.
There could be as much as a month’s worth of rain falling in just a few hours and this would lead to flash flooding. Frequent lightning, large hail and gusty winds are additional hazards that would bring transport disruption.
This area of rain could become slow-moving across northern Scotland during Sunday, with a threat of some flash flooding.
Low pressure looks set to take hold of the weather across the UK on Sunday and Monday with further widespread showers and thunderstorms likely.
Thunderstorms always bring large variations in rainfall amounts from one place to the next, but some again could bring heavy downpours with a few areas of flooding.
