Environment

Weather extremes: What’s causing the heatwave in Ireland, deadly floods in Europe?

‘Omega’ weather system sees high pressure – typically bringing warmer weather – sandwiched between two low-pressure systems

Household items and cars on the street in Istanbul after flooding blamed on the ‘Omega’ weather system currently over Europe. Photograph: EPA
Household items and cars on the street in Istanbul after flooding blamed on the ‘Omega’ weather system currently over Europe. Photograph: EPA
Nadeem Badshah
Thu Sept 07 2023 - 09:13

An unusual omega weather system is being blamed for both the unseasonal heatwave in Ireland and the United Kingdom, and the catastrophic flooding in Bulgaria, Greece and Turkey.

An omega system – named after the Greek letter omega because of its shape – is one in which high pressure – which typically brings warmer and more settled conditions – becomes sandwiched between two low-pressure systems.

The heatwave is being driven by tropical storms pushing a high pressure system over Ireland and the UK, with the jet stream having moved to the north and bending into what is known as an omega blocking pattern.

Blocks can interrupt the normal eastward progression of European weather systems and can last for months.

READ MORE

In Ireland, temperatures are set to hit highs of up to 28 degrees during the current spell of warm weather. A status-yellow high temperature weather warning is in place until Saturday morning.

In the UK, Neil Armstrong, chief meteorologist at the Met Office, said: “An active tropical cyclone season in the North Atlantic has helped to amplify the pattern across the North Atlantic, pushing the jet stream well to the north of the UK, allowing some very warm air to be drawn north.

“It’s a marked contrast to much of the meteorological summer, when the UK was on the northern side of the jet stream, with cooler air and more unsettled weather.”

Elsewhere in Europe, however, weather brought by the omega system has proved fatal. At least 12 people have died in Bulgaria, Greece and Turkey as torrential rainstorms caused flash floods, sweeping away bridges and inundating streets, homes and public buildings.

The low-pressure areas are affecting either side of the Mediterranean, resulting in Storm Daniel bringing torrential downpours to parts of Greece, including the port city of Volos. Greek authorities have said the weather was the most extreme, in terms of rainfall, since records began, Reuters reports.

In northwest Turkey, at least seven people died after heavy rains unleashed a torrent that swept through a campsite in the northwestern Kırklareli province, near the border with Bulgaria. – Agencies