Why DANA was catastrophic in Valencia: a storm train self-healed for hours in the same place

DANA was the ‘conductor of the orchestra’, the basic situation that allowed the torrential rains to occur for hours and cause flooding. But there were more ingredients necessary for the misfortune that they have experienced throughout the province of Valencia, which received accumulated amounts of more than 200 liters per square meter in a large area and which reached the 400 liters per square meter in Chiva, Buñol or Turís, more than 300 liters per square meter in Requena and around 275 in Utiel. Specifically, it was the wind structure, with an easterly flow in the lower layers and a southern component flow at high levels, which favored the appearance of ‘organized storms’. And these organized storms self-regenerated in the inland area of ​​Valencia, unloading again and again in the same area. «For an observer on the surface everything happens as if the storm were static, but in reality They passed one after another«explains Meteored meteorologist and retired member of the State Meteorological Agency, Francisco Martín.

Specifically, the variation of wind flows in high and low layers generated what is called a mesoscale convective systemexplains Martin. “They are groups of storms that organize among themselves to give rise to phenomena of longer duration, greater intensity… This is what we had yesterday over Valencia.” If a normal storm lasts between 10 and 30 minutes, these storms join forces and are capable of generating storms that They last six hours or more.

«But in Valencia, in addition, this convective system generated a stationary storm train, which is a set of storms that pass through the same place successively, generating abundant and torrential accumulations.” They act as if the same storm hit the same place for many hours. «It’s the worst thing there can be from the point of view of precipitation and torrential rains,” acknowledges the meteorologist. It is a “uncommon” phenomenon says the expert, but it is not unusual in the Mediterranean area, not only in Valencia, but on all coasts that are concave and have the mountains very close, since they favor this type of atmospheric configurations.

Added to all this was also the Mediterranean humidity“first-class gasoline,” summarizes Martín. The water and air temperatures were above normal, and that humidity does not disappear on its own. You need a cold front, a storm or a DANA to absorb that moisture. “The date doesn’t matter,” says Martín, as long as the factors are in place. And this time they have occurred to generate the most intense DANA that has occurred in the 21st century and the third in 30 or 40 years in the Valencian Community area.