Why the Valencian Country Dana was so exceptional

BarcelonaThe climate crisis has taken on a new dimension since the catastrophe a year ago in the Valencian Community. That historic storm showed that we are not prepared to face the negative effects of unchecked global warming. Extreme weather events have been increasing for years in the Mediterranean, one of the planet's most vulnerable areas to climate change. And the catastrophic storm of that fateful night of October 29th was the worst possible example of where we are.

But why was that storm so exceptional? In that case, several factors came together to create the perfect storm. From extraordinary weather conditions to the terrain, to warming seawater and poor urban management. A combination that generated a type of natural disaster that is occurring with increasing frequency.

An extraordinary storm

The concept of ana comes from the acronym of isolated depression at high levels. It's a low-pressure system of cold air at altitude that separates and detaches from the wind currents from which it originates. When it becomes isolated in the atmosphere, it stagnates for days in one area and causes sudden weather changes in specific areas. Not all low-pressure systems cause problems, but this one was particularly extraordinary.

At the end of October last year, a very deep low-pressure system developed, its core located in the Gulf of Cádiz. This position triggered the impulse of counterclockwise winds laden with moisture from a warmer-than-normal sea that directly impacted the Valencian Country. The collision between these offshore winds and the instability with cold air at altitude generated significant rainfall accompanied by torrential downpours.

But one of the key factors was the topography of the area. These warm, humid winds collided directly with the inland mountains of the Valencian region. The air suddenly rose in altitude and, as it condensed, generated large clouds and torrential rainfall that lasted for many hours in this area. This is what is known as the mountain leverage effect, aggravated by an excessively warm sea.

A situation like this already causes a lot of rain. But in this case, the figures were extraordinary and record-breaking. In inland Valencia, more than 500 l/m² accumulated in some places, with the most notable being the more than 770 l/m² that fell in just fourteen hours in Turís, in the Ribera Alta region, 184 of them in one hour. These figures have never been seen since records began in Spain, and they show that the climate crisis is causing increasingly extreme weather events.

Urban management and social impact

The massive amount of water that fell in just a few hours caused ravines, rivers, and streams throughout the area to overflow their banks. The resulting wave of water especially devastated the final stretch of the riverbeds, where, curiously, there had been little rain and where many towns and neighborhoods built in flood zones are located. Therefore, the combination of climate crisis and poor urban management made the disaster much worse.

In the wake of this tragedy, the word "dana" generates a social impact every time one occurs. This catastrophe is prompting changes to the weather warning systems for the population. Furthermore, the Aemet (Mexico City Meteorological Agency) has recently begun naming the potentially most dangerous danes to differentiate them from those that pose no risk. This way, they hope to avoid generating unnecessary alarm among the population and avoid stigmatizing this word, as happened with the term "dana" (storm). cold drop years back.