A “strange arrangement” has caused the jet stream to burst off the coast of Portugal, leaving a spinning vortex to flow air from North Africa to Britain, the Met Office revealed. The harmless-looking but deadly meteorological feature will advance toward Britain as high pressure builds to concentrate the blistering heat.
Temperatures are set to skyrocket today before potentially reaching 41C at the start of the week, triggering a national emergency.
Meteorologist Aidan McGivern said: “On Sunday temperatures will start to rise in much of England and Wales, and this is the first day that temperatures have really started to rise.
“The reason for this is the jet stream, which has a rather odd arrangement with a cut off low high up in the atmosphere, which we call a ‘vortex’.
“This is circulating along the Portuguese coast and has helped build up and concentrate the heat in Spain and Portugal, and we’ve seen some remarkable temperatures, so high that even I don’t believe it.
“Until Sunday and the beginning of the week this vortex will begin to approach, and Monday and Tuesday a plume of very hot air will cover the UK.”
The vortex will join forces with a massive high-pressure area that will choke Britain and force the air to the ground, causing it to warm up quickly.
It will trap boiling air under a dome of heat as it engulfs Britain, pushing temperatures to 33°C today and steadily rising for the next 72 hours.
However, this unstable arrangement will collapse mid-week, causing a dramatic drop in temperature.
Mr McGivern said: “High pressure is spreading widely across the UK, causing temperatures to rise due to an effect called ‘subsidence’ – descending air that becomes hot as it is compressed.
“The jet stream allows for high pressure, allowing for dry sunny conditions and also above-average temperatures.
“But we also have this vortex that has helped to trap heat in the south of the UK.
“It’s Sunday, Monday and Tuesday that that heat is being pushed our way, but this is a very unstable line-up and a change is on the way on Wednesday.”
The latest weather models show temperatures in the south and center of Britain reaching 30C to 33C today, while the north remains pleasantly cool in the high teens and low 20Cs.
Extreme heat will increase early tomorrow with highs of 38C in the south before noon and between 20C and 25C in Scotland.
Temperatures remain at an astonishing 38C at midnight, before rising to 41C on Tuesday.
A massive drop in temperatures on Wednesday will see highs as low as 17°C across much of Britain and 28°C in the south east.
Health chiefs have warned that extreme heat could push the death toll into the thousands.
They have urged people not to go outside in the heat and limit activities when temperatures are highest for the next two days.
The government held an emergency meeting of the Cobra late last week as the alert level was raised to a level 4 “national emergency.”
dr. Agostinho Sousa, head of extreme events and health protection at UK health security, said: “We are likely to hit record temperatures early next week, and it’s important we all know how to stay well in hot weather.
“Check vulnerable friends, family and neighbors to make sure they stay hydrated, stay cool and know how to keep their homes cool.”
Professor Penny Endersby, chief executive of the Met Office, added: “This is the first time we have issued a Red National Severe Weather warning for extreme heat and the first time 40C has been forecast in the UK.
“In this country we are used to treating a hot spell as an opportunity to go play in the sun.
“This is not such weather.”