The warning from the Aemet (Agencia Estatal de Meteorología), has been categorized as “important risk” (level orange). Despite being something that happens frequently, it is not without risk. A rissaga is a meteorological-marine phenomenon that usually has a special impact on the port of Ciutadella, in the west of the island. Also in other nearby ones.
The alert is in effect from 6 pm on Wednesday, June 19 until 8 am on Thursday, June 20 and there is a 40 to 70 percent probability of occurrence. AEMET warns of “possible rissagas in Menorca”, Catalan word for meteotsunami.
How this phenomenon is formed
We could say that it is a type of ‘meteotsunami’, a wave or several waves of great amplitude caused by sudden changes in atmospheric pressure. These variations cause rapid oscillations of the sea level, which can reach up to several meters in a short period of time, reports Meteored.
A meteotsunami occurs when large waves are caused by alterations in atmospheric pressure, often by sudden weather events such as thunderstorms. It is different from a tsunami that is due to seismic activity, such as earthquakes under the seafloor.
The process begins when an atmospheric disturbance, such as a storm, generates sudden changes in pressure. These disturbances move out to sea and, if conditions are favorable, generate waves that are amplified as they approach the coastline. In the case of Ciutadella, the configuration of the port and the topography of the island enhance these effects, making them a particularly notable and dangerous phenomenon.
In July 2018, a meteotsunami was recorded in both Mallorca and Menorca, causing waves that crashed hotels, bars and restaurants along the coast. In the process, it washed away sun loungers and moorings.
Moments before that meteotsunami, the harbor emptied of water almost completely, so that boats reached the bottom of the harbor. Moments later, and very quickly, the water violently returns to the harbor, causing it to overflow and bring sailboats and yachts onto the docks.
The meteorologists Agustí Jansà and Climent Ramis defined in 1983 the meteorological situation favorable to gust events in the Balearic Islands, which can be summarized as follows:
Strong southwesterly winds at an altitude of 5,500-9,000 meters. Warm African air at about 1,500 meters, with a layer of thermal inversion. Middle layer instability around 5,500 meters. On the surface, east-southeast wind, with cloudy skies and frequent mud showers.