The phenomenon of “Ianos” was extreme, mainly in terms of rainfall, say the meteo scientists of the National Observatory of Athens (EAA) K. Lagouvardos, B. Kotroni and S. Dafis in a relevant publication on the website of the service.
Indicatively, according to the network of meteorological stations of EAA / meteo.gr, 317 mm of rain were measured in Pertouli, while in Karditsa and Mouzaki more than 200 mm were measured in less than 24 hours. Comparatively, as they emphasize, the average annual rainfall in Athens does not exceed 400 mm. They also note the large geographical area that received high rainfall, resulting in an increased chance of flooding in these areas.
Another extreme element of Janus was his long life with tropical characteristics and its intensity, which classify him as one of the most powerful Mediterranean Cyclones recorded since 1969, that is, from the beginning of satellite observations.
The Mediterranean cyclone (medicane) is a deep barometric low, which draws its energy through the transfer of heat from the warm waters of the Mediterranean and the release of heat during storms near its center. A cloudless “eye” may appear in its center, similar to hurricanes, while its characteristics are hybrid, showing similarities to tropical and exotropic cyclones.
According to EAA-meteo researchers, in the Mediterranean such barometric systems occur on average one and a half times a year, ie one to two Mediterranean Cyclones in a year, while other years may not be created. In the region of Greece, since 1982, six Mediterranean Cyclones have been recorded, four of which in the period 2016 – 2020. Although this is not an unprecedented weather phenomenon in our region, the growing trend of their occurrence during the last decade is a cause for concern. as well as increasing their intensity.
The torrential rains in Thessaly and Anat. Solidly connected directly with Janus, according to the meteo. Janus functioned as a pump for extracting water vapor from the warm waters of the Mediterranean, transporting extreme amounts of water vapor high into the atmosphere. This saturated the atmosphere with water vapor and as a result there was rapid rainfall. In addition, Janos, in combination with the higher atmospheric pressures around it in the Eastern Mediterranean, significantly increased wind speeds, even away from its center.
In addition, the convergence of gas masses that moved at high speed on the mountainous terrain of the central mainland, created the conditions for the formation of rain clouds and their stay in these areas for a long time. Finally, the prolonged duration of heavy rains in Thessaly and Central Greece are directly due to the slow movement of Janos on Friday and Saturday.
The phenomenon was largely predictable, according to meteo, according to which “the only failure of the forecast was the rain in Athens at noon / afternoon on Friday 18/9, which were delayed by 12 hours”.
To better monitor severe weather events such as Janos, researchers point out that there is know-how at the national level, but it requires investment in metering infrastructure and their completion in early warning systems. They also report the “lack of a national meteorological radar network for detailed weather monitoring, which will improve reaction time and extreme warnings.” Also, several more areas of our country should be covered with meteorological stations “.