Omega Block: The Unusual Weather Pattern Behind Europe’s Heatwave and Devastating Floods

An unusual weather system, known as an omega block, is being linked to both the scorching heatwave in the UK and the devastating flash floods that have hit Bulgaria, Greece, and Turkey. The Omega block, which typically brings warmer and more settled conditions, has become stuck in a rare pattern where a zone of high pressure is sandwiched between two areas of low pressure, leading to extreme and unseasonal weather.

In north-west Turkey, at least seven people lost their lives when a torrent of rain swept through a campsite, leaving a trail of destruction in its wake. The flooding was so severe that it swept away bridges and inundated homes, public buildings, and streets. The city of Kırklareli province, near the border with Bulgaria, was among the hardest hit.

Meanwhile, parts of Britain have experienced temperatures reaching a sweltering 30C (86F) in the first week of autumn, with Saturday expected to be the hottest day of the year so far. The unusual warmth has been attributed to the omega block’s ability to push the jet stream, the fast-moving band of air that influences the weather, to the north of the UK, allowing warm air to flow in from the Atlantic.

Neil Armstrong, chief meteorologist at the Met Office, noted that an active tropical cyclone season in the North Atlantic has contributed to the amplification of the pattern, resulting in unusual warmth and flooding. Armstrong described the situation as a “true atmospheric stalemate” where a heat dome, flanked by two strong storms, has created an intense blockage that is dumping heavy rain over parts of Greece.

The flooding in Greece has been catastrophic, with Storm Daniel bringing torrential downpours to parts of the country, including the port city of Volos. The Greek authorities have reported that the weather was the most extreme, in terms of rainfall, since records began. The volume of water that fell in Pelion on Tuesday was equivalent to the annual rainfall of London, according to meteorologist George Tsatrafyllias.

As a result of the extreme weather, travel company Jet2 has canceled all flights and holidays to the Aegean island of Skiathos until September 12. The authorities have issued warnings for the cities of Trikala and Karditsa in central Greece, as the rainstorm is not expected to subside before Thursday.

The unusual pattern has been described as a textbook example of an omega block, with the jet stream acting as a “traffic jam” that prevents the normal eastward progression of European weather systems. While omega blocks can last for months, the situation in Europe has been particularly extreme, with temperatures soaring and heavy rainfall causing widespread flooding.