Although extreme, but an expected meteorological phenomenon for the time of year and the geographical area, the bad weather “Dana” that hit Valencia, leading to the death of dozens of people, is judged by the experts.
«Every year in the autumn months, barometric lows are observed in the Mediterranean, i.e. areas with low atmospheric pressure. These create instabilities that favor the development of storm clouds that usually give large amounts of rain” Dr. explained speaking to “Vima”. Konstantinos LagouvardosDirector of Research at the Athens Observatory, and added: “These phenomena usually start from the Western Mediterranean in September, when the temperature of the sea waters is still elevated and they gradually move eastward. The areas that are mainly affected are the coasts of Spain (Valencia, Catalonia), the coasts of Southern France, Northern Italy (and mainly the Liguria region), the Adriatic coasts and of course our country».
Although in Greece the heavy rains are observed mainly in October and November, “Daniel” that hit Thessaly last year in September proved that all three months of autumn are dreaded for extreme rains. But how do high sea temperatures relate to high amounts of precipitation?
«Increased sea temperatures mean intense evaporation of water and strengthening of storm cloudsDr. Lagouvardos tells us, reminding us that “Daniel” was fueled by the increased temperatures in the Ionian Sea. Increased ocean temperatures combined with cold air masses high in the atmosphere create what meteorologists call a “cold lake,” the instability that breeds high levels of precipitation.
And according to a wealth of data, the climate crisis increases the frequency and heightens the intensity of such phenomena. However, are the sea temperatures off Valencia, which were not particularly elevated, enough to explain how deadly the bad weather “Dana” was?
«The consequences of a bad weather event are a function of many factors and not just the amount of rainfall. In this case we are dealing with the vulnerability of cities. The increased population density, the reduction of peri-urban greenery, the non-resilience of infrastructure are decisive factors for the consequences of extreme or less extreme weather events” says Dr. Lagouvardos, who, when asked what would happen if Athens were hit by a similar weather phenomenon, does not mince his words: “It could be disastrous! However, the fact that we cannot prevent such phenomena from happening does not mean that we are completely unprotected. Their prediction, which is possible one or two days before they happen, and informing residents to limit their movements in this aim».
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