Was it necessary to suspend classes on Monday?

Palma"The storm system that on Monday evening was threatening Mallorca deviated and headed towards Menorca: a reminder to keep in mind that, however good the models may be, there always remains a margin of uncertainty". With this reflection, the great Agustí Jansà, former provincial director of Aemet in the Balearic Islands, recalled a reality that we often forget when we talk about meteorology: predictions are always based on probabilities.

We live in an immediate society, in which we want to know at what time it will rain, how many liters will fall, and in what exact place the precipitation will take place. But those of you who want a perfect weather forecast should perhaps first look up in the dictionary what exactly that word means: prediction.

Any prediction is subject to a margin of error. In fact, the forecasts that justified Monday's red warning predicted a high probability of extreme rainfall, but also the possibility that the phenomenon would not occur exactly as expected. Traditional meteorological models work with complex mathematical algorithms that interpret various possible situations, called scenarios. Today there are also models that incorporate artificial intelligence, but none of these systems eliminate uncertainty.

Here we have a problem. In the past, with 72 hours of notice, we could already consider many predictions reliable. Now, despite the great advances in models, there are very complex meteorological situations, especially intense and localized storms, in which it is so difficult to fit the pieces of the puzzle together that forecasts can change even when only 6 or 12 hours remain.

And that is what happened on Monday. The models showed a significant probability of very intense rainfall in the south of Mallorca, with scenarios reaching 300 liters per m². Finally, the storm system deviated towards Menorca. The public must understand that every prediction is based on probabilities and that warnings and alerts are issued taking into account the risk to protect the population.

At this point I would also like to pause, because a warning and an alert are not the same thing. A meteorological warning is announced by Aemet and can be red, orange, or yellow depending on the expected intensity of the phenomenon. In the case of heavy rain, the liters per m² that can fall in a given time are taken into account. On the other hand, alerts are declared by Emergencies according to the risk that may exist for the population. In the Balearic Islands, the Meteobal plan establishes different severity indices: IG-2, IG-1, and IG-0.

By this I mean that we can stop having a meteorological warning and continue in a state of alert. Because, even if it is no longer raining, the infrastructure may have been damaged and collapses of bridges, roads, and other buildings can occur. The danger does not necessarily disappear when it stops raining.

And we arrive at the question that many asked themselves on Monday: was it necessary to suspend classes if, in the end, the most intense rainfall did not reach Mallorca?

To answer it, I think three things must be very clear.

The first is that any meteorology enthusiast, with few exceptions, would have perfectly understood the declaration of a red warning by Aemet. It was not a single model that announced extreme precipitation. Both regional and global models predicted very intense rainfall, especially in the south and east of Mallorca (figure 1). With these forecasts on the table, the risk was significant enough to take preventive measures.

The second is that, like any prediction, warnings are subject to errors. And we have several examples of this. In 1989, torrential rains surprised municipalities such as Felanitx, Manacor, and Portocolom, where there were three fatalities. We have a much more recent example in our collective memory: the Sant Llorenç flash flood of October 9, 2018. A convective train caused torrential rainfall that exceeded 200-250 liters per m² in a few hours, with a red warning that arrived too late, when the Les Planes torrent was already overflowing. The consequence, we all know it: 13 people dead.

The third is what happened this very Sunday in the south of Valencia and the north of Alicante. A red warning was declared for very intense rainfall and the forecasts even fell short: in the Atzúbia area, more than 700 litres per m² were accumulated during the episode (figure 2).

Imagine if a red warning had not been decreed in this case. Thousands of people, with the tourism that exists in the areas of La Safor and Marina Alta, could have travelled freely through places where the torrents overflowed and reached the sea with very violent force. How many more victims could there have been? We cannot know, but the risk was enormous. And it is enough to remember what happened on 29 October 2024 in Valencia, when the ES-Alert arrived too late, to understand the consequences that not acting in time can have.

That is why I believe it is important not to judge preventive decisions only by what ends up happening. On Monday, classes were suspended and, fortunately, the worst-case scenario announced by the models did not occur in Mallorca. But this does not mean that, with the information available at that time, the decision was wrong. When the decision is made to suspend school activity, it is not about guessing whether it will rain on a specific school, but about preventing thousands of students, families, and teachers from having to travel in a situation of potentially extreme risk.

Behind the decision to send an ES-Alert is a team of professionals trained in meteorology, hydrological risk prevention, and civil protection who assess the need to alert the population. Obviously, decisions can be reviewed and the way of informing and managing emergencies can always be improved. But the principle of prevention must have a fundamental weight when there is the possibility of a phenomenon that can put lives at risk.

The fact that the worst-case scenario did not occur does not mean that it was a mistake to prepare. Because a human life is worth infinitely more than any prediction.