Southerly winds will push a “Spanish plume” across parts of the UK this weekend, with hot and humid weather forecast – including heavy rain and thunderstorms.
The warm air from the south will from Friday and into Saturday bring a surge in temperatures in the south and eastern England, the Met Office said. Areas likely to have the hottest weather include London, where temperatures could reach about 30C on Saturday, Norwich and Cambridge (28C), Bath, Birmingham and Lincoln (25 or 26C).
At the same time, cooler air from the Atlantic is blowing in from the north and west, bringing cooler weather to Scotland and north-west England. Thunderstorms are forecast where the two systems meet across east Wales and the parts of the Midlands.
The Met Office issued a yellow “be aware” warning for rain on Saturday for residents in eastern England. Hot, unstable air is expected to push up from France into the UK, bringing temperatures into the low 30s and triggering torrential thunderstorms, with the risk of more than 30mm in less than an hour.
However, Helen Roberts, of the Met Office, played down reports of possible tornadoes in the south-east. “There is the potential for some thundery showers on Saturday afternoon, most likely in east Wales and parts of England,” she said. “Basically we have got a cold front straddling the UK. To the north-west it’s cooler, fresher and windier conditions, and then to the south-east of the front it’s much warmer, drier and brighter.”
Rain will begin to spread across central and western parts of the UK over Saturday night and Sunday, according to the Met Office forecast, as the weather front pivots across the country.
However, a Met Office blogpost says there is some uncertainty as to how this will play out, since the point at which the front will pivot is not fixed. The rain could be heavy and forecasters will review whether a national severe weather warning is needed.
A Spanish plume is a colloquial description of a weather situation in which a large southwards dip in the high altitude jet stream develops to the west of Europe, encouraging a deep southerly wind flow. This pushes hot and humid air from Iberia north and north-east into northern Europe, including the UK.
The proximity of active weather systems moving along with the jet stream and heat from the summer sunshine can encourage thunderstorms to develop. The strong winds from the jet stream help to organise the thunderstorms and can aid in their severity.
