page_title: Mediterranean tropical-like cyclone
section_title: Numa (16–19 Nov 2017)
hierarchical_section_title: Mediterranean tropical-like cyclone / Notable medicanes and impacts / Numa (16–19 Nov 2017)
caption_attribution_description: English: Numa, a Mediterranean tropical-like cyclone, displaying a distinct eye-like feature over the Ionian Sea on 18 November 2017.
context_page_description: Mediterranean tropical-like cyclones, often referred to as medicanes but sometimes also as Mediterranean cyclones or as Mediterranean hurricanes, are meteorological phenomena observed over the Mediterranean Sea. On a few rare occasions, some storms have been observed reaching the strength of a Category 1 hurricane. The main societal hazard posed by Medicanes is not usually from destructive winds, but through life-threatening torrential rains and flash floods.
  The occurrence of Medicanes has been described as not particularly rare. Tropical-like systems were first identified in the Mediterranean basin in the 1980s, when widespread satellite coverage showing tropical-looking low pressures which formed a cyclonic eye in the center were identified. Due to the dry nature of the Mediterranean region, the formation of tropical, subtropical cyclones and tropical-like cyclones are infrequent and also hard to detect, in particular with the reanalysis of past data.
context_section_description: On 11 November 2017, the remnant of Tropical Storm Rina from the Atlantic contributed to the formation of a new extratropical cyclone, west of the British Isles, which later absorbed Rina on the next day. On 12 November, the new storm was named Numa by the Free University of Berlin. On 14 November 2017, Extratropical Cyclone Numa emerged into the Adriatic Sea. On the following day, while crossing Italy, Numa began to undergo a subtropical transition, though the system was still extratropical by 16 November. The storm began to impact Greece as a strong storm on 16 November. Some computer models forecast that Numa could transition into a warm-core subtropical or tropical cyclone within the next few days. On 17 November, Numa completely lost its frontal system. On the afternoon of the same day, Météo France tweeted that Numa had attained the status of a subtropical Mediterranean depression. During the next several hours, Numa continued to strengthen, before reaching its peak intensity on 18 November, as a strong subtropical storm. According to ESTOFEX, Numa showed numerous 45 knots (83 km/h) flags of 10-minute sustained winds in satellite data. Between 18:00 UTC on 17 November and 5:00 UTC on 18 November, Numa acquired evident tropical characteristics, and began to display a hurricane-like structure. ESTOFEX again reported 45 knots (83 km/h). Later on the same day, Numa made landfall in Greece with a station at Kefalonia reporting peak winds of 60 knots (110 km/h) at 998 hPa. The cyclone rapidly weakened into a low-pressure area, before emerging into the Aegean Sea on 19 November. On 20 November, Numa was absorbed into another extratropical storm approaching from the north.
  Numa hit Greece at a time when the soil was already heavily soaked from other storm systems that did arrive before Numa. The area was forecast to receive up to more than 400 millimetres (16 in) of additional rains in an 48 hours period starting with 16 November. No rainfall forecasts or measurements are known for the following days while Numa was still battering Greece. Numa resulted in 21 reported deaths. At least 1,500 homes were flooded, and residents had to evacuate their homes. The storm caused an estimated US$100 million in damages in Europe and was the deadliest weather event Greece had experienced since 1977.
caption: Numa on 18 November 2017
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