Start of the week with more calm but without clearing up completely

BarcelonaAn extraordinary mesoscale convective system has generated torrential rains, especially in the pre-coastal and central coastal areas, with exceptional amounts such as, for example, the 288 l/m² in Vilassar de Mar, the 255 l/m² in Mataró (Can Canyelles) and the 248 l/m² in Granollers. Ultimately, the medican (Mediterranean hurricane) did not form, but, as the models indicated, the amount of accumulated rain was historic. Worth noting are the 68 l/m² that fell in just half an hour in Granollers, a figure of extraordinary torrential intensity. The storm system fully affected the Maresme and the Western and Eastern Vallès. In Pineda de Mar, several rescues were carried out in ground-floor apartments and vehicles trapped by the water. In the city of Barcelona (Can Bruixa), the record for accumulated precipitation in 24 hours was broken (data since 1914), with a total of 213 l/m².

The torrential intensity and the exceptional amount of water accumulated in a few hours caused the flow of the Besòs River to reach 936 m³/s in Santa Coloma de Gramenet, well above the more than 500 reached during Storm Gloria. To give us an idea, the flow of this river (which normally carries 20 m³/s) ended up tripling the water of the Ebro River. Early this morning, there was a hydrological alert for possible flooding of the Besòs and the Tordera, where, unfortunately, there has been one fatality. Another person lost their life in Montornès del Vallès and there is another missing person near the Pineda stream.

Meteocat has updated the cumulative rainfall data during this episode (until 10 a.m.):

Monday with a hangover from a historic episode

During the early hours there will remain symptoms of instability, with more residual showers, locally intense along the coast, especially on the Costa Brava and the Ebro Delta. In the rest of the coast and the pre-coastal area, low clouds will appear, and inland the sun will shine with some thin clouds. Banks of low clouds and scattered fog will also appear inland, which will alternate with large clearings. Thermometers will recover at midday. In the northeast, the thermometer will rise a little more, with values that will move between 22 ºC and 26 ºC.

During the afternoon, clouds will develop due to the proximity of a cold air pocket coming from the Atlantic. They will appear downpours, scattered in nature, also in the form of a storm. The showers will fall in the Pyrenees, the Pre-Pyrenees, especially in the oriental. They will also unload in the pre-coastal area and in some points of the northeast.

The Meteocat alerts are for intense rain and accumulations of more than 40 mm in 30 minutes throughout Monday, until 8 p.m. The maximum danger level is 4 out of 6:

Unsettled week, with new showers

With the approach of the cold air pocket, the weather will become complicated again and will be unstable. On Tuesday and Wednesday, showers and some storms will repeat, most likely in mountain areas, in inland Catalonia, and in the pre-coastal areas. It will not clear up completely until the end of the week, and temperatures have no intention of dropping at all.

These situations of marked instability, such as the one experienced this weekend, are typical of autumn, aggravated by a sea much warmer than it should be at this time of year. This year, records have been set for the average sea surface temperature in the Mediterranean, which reached 28.6 °C on August 14th (data from the Copernicus Marine Service, @CMEMS_EU). In Catalonia, the sea has reached its highest average recorded temperature this summer: 21.1 ºC.