Storm Daniel

Storm Daniel, also known as Cyclone Daniel, was an erratic, weak but catastrophic tropical cyclone that became the deadliest Mediterranean tropical-like cyclone in recorded history, as well as the second-costliest tropical cyclone on record outside of the North Atlantic Basin (after Typhoon Doksuri). Forming as a low-pressure system around 4 September 2023, the storm affected Greece, Bulgaria, and Turkey with extensive flooding. The storm then organized as a Mediterranean low and was designated as Storm Daniel. It soon acquired quasi-tropical characteristics and moved toward the coast of Libya, where it caused catastrophic flooding caused by the collapse of two dams, Derna and Mansour, resulting in the flooding of the Wadi Derna river causing great damage to the city of Derna. After collapsing the two dams, Storm Daniel degenerated into a remnant low. The storm was the result of an omega block; a high-pressure zone sandwiched between two zones of low pressure, with the isobars shaping like the Greek letter omega (Ω).

In Greece, severe rainfall led to flooding that caused more than two billion euros in damage, making it the most costly recorded storm for the country. Libya was hit the hardest, with torrential rains causing two dams near the city of Derna to fail. This resulted in over 5,900 deaths and 7,000 injuries, with at least 8,000 others missing. Libya's vulnerability to such disasters was blamed on its civil war, which damaged critical infrastructure and left it in poor condition before the storm. In the aftermath, several countries along the Mediterranean Sea pledged to provide aid to affected countries.