Heatwave in Europe: Sipping a Pina Colada at 11am? Understanding why the UK, France and Spain are so hot

A British tourist was spotted sipping a Pina Colada at 11am. “It’s so hot. It’s absolutely boiling,” he told France24 while walking the streets somewhere in Europe this May.

Europe, including the UK, is reeling under severe heat. Thanks to the “heat dome”, a pocket of warm air trapped under a high pressure system that is driving unusually high temperatures across Europe.

Millions of people across Europe were exposed to extreme and exceptionally high temperatures on Tuesday, with 40 drowning deaths reported in France over the past week as residents sought relief from the scorching heat.

Britain’s MET has issued a “red extreme heat warning” for Wednesday and Thursday, with temperatures expected to reach at least 39C – breaking June’s daily temperature record. “There remains the possibility that it will be exceeded in places,” the MET office said in its forecast.

In France, forecasters said temperatures in Paris could hit 40 degrees Celsius this week, which would be unprecedented for June. Météo-France said “exceptionally high temperatures, both during the day and at night”, were expected.

Spain’s national weather service Aemet also issued red alerts on Tuesday for temperatures of 44°C (111°F) in southern Andalusia, as well as warnings of thermometers hitting 40°C in the normally mild regions of Cantabria and the Basque Country along its northern Atlantic coast.

According to several experts and reports, this unusually hot weather is being driven by the so-called “heat dome.”

“Heat domes are happening around the world, and the one over Europe this week is closing in on days of near-record highs across Britain, Spain and France,” the New York Times reported.

What is a heat dome?

A heat dome forms when a massive bubble of high-pressure air parks over an area, UNDDR explained in a video.

“It traps heat like a lid on a pot,” he says.

According to the agency, this happens when the jet stream — the high river of air that usually moves weather systems — slows down or gets stuck.

When this happens, extreme events such as heat waves, torrential rains or wildfires are stuck in place for days or weeks.

Omega block

Omega Block and heat dome are related but not the same. Simply put, the Omega Block is the cause and the “heat dome” is the effect.

Reuters quoted a weather analyst as saying the so-called “Omega Block” was causing an intense and slow-moving European heat wave, prompting authorities across the continent to issue heat warnings.

The pattern is known as an “Omega block,” with a dome of hot air trapped in the middle and cooler air masses on either side, the report added.

It’s called the Omega Block because it’s shaped like a Greek letter with a bulge of hot air in the middle and cooler air on either side, allowing temperatures to rise day by day.

The Royal Meteorological Society (RMS) explains that the position and strength of the jet stream can lead to blocking situations such as an omega block, where high pressure ends up sandwiched between two low pressure systems, forming a shape like the Greek letter Ω.

Jet streams are strong winds high above the Earth’s surface that help develop and drive low pressure areas around. They often move from east to west, “but sometimes they can become blocked, often when the jet stream weakens and bends.”

The high pressure stops the weather fronts from moving so they either go around the edges of the highs or stall.

“Your position under an omega block will determine the weather you get. High temperatures tend to be dry and settled, while low pressure brings wet and windy conditions. Weather blocks can last for days, weeks or even months, as in the summer of 1976,” says the Royal Meteorological Society (RMS).

‘Under the Dome’

The Royal Meteorological Society (RMS) says the problem with a stubborn high pressure area is that the already warm or hot air trapped under high pressure will continue to heat up and form a heat dome.

“The hot air will rise into the atmosphere, but the high pressure acts as a lid and causes the air to sink, or sink. As the air descends, it warms up by compression, and the heat builds up. The ground also heats up, loses moisture, and melts more easily,” he explains.

“Until the pressure pattern changes, the high will continue to exacerbate hot conditions, bringing the risk of wildfires, drought and health problems,” he adds.

Experts say human-induced climate change is making these patterns more likely.

Why is Europe so hot?

Britain’s MET said on June 17 that the developing heatwave was being driven by a strong area of high pressure over continental Europe.

“Its high pressure promotes large-scale descending air, which suppresses cloud formation, allows for longer sunshine and leads to increased temperatures through compressional heating,” he explained.

“Great Britain Caught Between Two Air Masses”

As Europe warms, the UK will experience a more complex and variable pattern. Low pressure in the northwest will continue to feed in areas of cloud, rain and fresher air, the UK MET said.

“At the same time, an expanding stream of warmer air from the continent will try to move north. This creates a sharp contrast across the UK, with the so-called baroclinic zone – the boundary between warm and cold air masses – located across or close to the ground,” he added.

Impact? Along this boundary, weather fronts will develop and move slowly, bringing outbreaks of rain, particularly to northern and western regions.

“This will result in a ‘rippling’ front, where bands of rain retreat and flow over similar areas over several days,” the UK’s MET added.