When it comes to damage and torrential rain, few meteorologists have as much knowledge and experience as Angel Rivera. With forty years dedicated to prediction, the person who was Aemet spokesperson between 2005 and 2012 began working at the National Institute of Meteorology (INM) when they were still called “cold drops.” He was the person who changed their name and who came up with the acronym for “isolated depressions at high levels” (dana) – in homage to his teacher, Francisco García Dana – which has become a sad protagonist in weather predictions.
in his book Today (Létrame, 2025), Rivera explains the atmospheric physics that underlies these episodes and proposes some improvements to the warning system, following examples such as the British and American ones, where the protocols are activated almost automatically. We chatted with him on the occasion of the anniversary of the dana october 2024 which left 237 dead.
It will be one year since the Dana of Valencia, what is the main lesson that an episode as dramatic as this one left us?
I believe that there is a need for much better coordination and communication between meteorologists, hydrologists and Civil Protection. The connection has to be much deeper, much more coordinated. That, assuming that then at other levels there is the coordination that must exist.
Isn't the successful management of the subsequent danas proof that it wasn't meteorological information or coordination that failed, but rather the decision makers?
But, even so, I miss more communication with the public. People have to have more updated information continuously, in order to also protect themselves, there has to be more flow of information.
The first thing that some politicians, like Feijóo or Mazón, did was point to scientists as responsible of the situation. To what extent is this harmful for the future?
It's something that usually happens. When I was spokesperson, it was also meteorology that ended up paying the price. Furthermore, I believe that the warning plans are not really known well, because it was said that it had rained much more than 180 millimeters. And it must be clear that 180 millimeters is the lower threshold of the red warning and from there it can rain 300 or 400 and it is very difficult for the models to tell you the exact amount. What you know is that it is a very critical situation for lives and property.
People have to have more updated information continuously, in order to also be able to protect themselves, there has to be more flow of information
Do we already know what exactly happened to form such a monster?
The Aemet published a report on the subject, but I think we need to go deeper. It was a truly powerful event. We always played with humidity and very hot sea air, which is the fuel, but I believe that more factors intervened. An engine is always needed in high layers, which causes the air to rise and create those powerful cumulonimbus clouds. I believe that that day over the Poyo ravine area there was probably a very powerful energy injection at maximum wind levels at altitude. And when it increases a lot, the atmosphere becomes unbalanced and those transverse currents, in my opinion, were what enhanced the growth of clouds.
What is CEVRA?
It is a State Environmental Risk Surveillance Center whose creation I propose: because we are facing a type of natural phenomenon that is challenging us more and more, from fires to floods. There should be a scientific and technical organization in which all these specialists are working in a coordinated manner and monitoring the situation. The last person responsible for giving a warning will always be the autonomous community, but this transversal body would have all the keys to what is going to happen. And that would allow very quick decisions to be made, even by the technical managers, without going through the politicians, because in a lightning situation, if you start talking you have lost. You have to react with very narrow time frames, 20 minutes, and speed up decision-making.
That is, designing systems in which it is almost enough to press a button, without having to talk to 14 people or wait for someone to show up at a meeting.
The thing is that we are going to a type of phenomenon so violent and so fast that many times the structure we have no longer serves us. We have to be much more agile in all this, but it has to come from a consensual reflection among those responsible.
We are going to a type of phenomenon so violent and so fast that many times the structure we have no longer serves us
That's a good lesson the Dana taught us, right?
But this country is so difficult that coordination seems like a dream.
One of the misunderstandings that you describe in your book is that we tend to think that the dana is right above the site where the most damage occurs and that's not the case, right?
The problem occurs especially in the front area of the depression where, due to atmospheric dynamics, updrafts are created. If you take the Mediterranean Sea below, with its 98 octane gasoline of warm and humid air, that is explosive.
The most frequent situation is that it is located over the Gulf of Cádiz and that the torrential rains go to the Mediterranean coast, right?
That is. Note that in order to form very powerful vertical ascents, three things are necessary. What we call a direction of vorticity is needed, for warm and humid air to enter from below and for the cloud to destabilize until creating another circulation that feeds itself. And another thing that happens is that not all danas give torrential rains, nor are all torrential rains danas. That's why naming it worries me.
I was going to ask him just about that. You, who were part of the team that coined the name “dana”, do not agree with giving them proper names. Because?
What I think needs to be identified in the Mediterranean area are the storms of intense rain or intense winds. If you announce a storm of intense rain in which 300 millimeters are possible, you also warn the public.
Is your fear that the word will be worn out, as happened with “gotacold”?
The thing is that it has already been spent, we are practically talking about dana as the equivalent of torrential rains. And in any situation that comes with torrential rains, the same thing will happen again. This thing about proper names originates in the late 90s in Europe, due to a series of very strong storms, but the danas have a much more difficult forecast. 200 liters may fall in one place and no liters fall ten kilometers away. Discriminating beforehand and giving names to the danas seems dangerous to me, because it may seem that if it doesn't have a name I won't take care of it. When it comes to danas, you always have to take care of them, because they are a bit treacherous.
Discriminating beforehand and giving names to the danas seems dangerous to me, because it may seem that if she doesn't have a name I won't take care of her.
How did they name the phenomenon?
It was during the Mariano Medina years and everything was cold turkey. What is happening now had already happened with the dana, which was equally useful for a torn one or a torn one. We thought many times about the name to put there and the idea of depression, an isolated storm at high levels, came up and in the end we came up with “DANA”. And it also coincided with the surname of a master meteorologist, Francisco García Dana. The funny thing is that we used it for 15 years in technical publications and it was not known to the public until it rose to fame.
All this will get worse with climate change but, counterintuitively, could there not be more danas, but rather more intense ones?
That's what I discuss in the book. If the polar jet is becoming more wavy, it is logical that it will strangle more times and release more damages. But it is true that it will be at higher latitudes, so the question is whether these danas, even if they form, will reach the Iberian Peninsula or will remain more in central Europe. That is an issue that is still poorly resolved. And then we will surely have more subtropical circulations that will also rise, and that is a meteorology that we still have very little known about.
That subtropical jet also brings us atmospheric rivers and more humidity, right?
Yes, it has worked like that until now. Let's say that there are times when large circulations of tropical and subtropical air are created from the Caribbean that reach our areas and are what cause rain storms. What happens is that it seems that now he is behaving a little differently. I really miss more research on all this, because we have a lot at stake. We have focused on the fuel and the lower layers, and that is perfect and we must continue with it, but, be careful, the engine is at the top and I believe the engine is changing.
I really miss more research on all this, because we have a lot at stake
Every meteorologist and climatologist I speak to has come to the same conclusion: the atmosphere is out of whack and increasingly unstable.
What happens is that as the air advances in the subtropical atmosphere towards the north, everything readjusts. What it is doing is producing large waves in the atmosphere, so that when a ridge rises it creates a heat wave and if the trough area catches you it can create damage.
Are we heading towards a climate of extremes all the time?
Of course, we are going towards more extreme climates and we must also take into account that there is more energy in the atmosphere. Since subtropical air is warmer and more humid, any phenomenon can have more energy than if it were not subtropical air.
All this occurs in a context in which those in power try to deteriorate the credibility of scientific sources. Or when the media focuses on a kid who predicts the weather by looking at ants. Are they undermining the credibility of experts?
The thing is that no one wants to convince themselves that prediction is always a probability. They tell you: don't talk to me about probability, tell me if it's going to rain or not. And that is deceiving yourself. The reality is that you have a 70% chance of getting 200 liters that morning. And if you want to invent something else, invent it. But don't blame it on scientists, because scientists go as far as they can and you have to live with that. As with so many things in life, everything is probabilities, but we don't like it.
How do you feel when you hear a popular player say that airplanes spray us with chemicals and that the contrails are not clouds?
Everyone distracts themselves as best they can.