AEMET has just talked about the December long weekend and it is bittersweet news because the “good weather” in December always has a trick
Yes ‘negative NOA‘, yes ‘storm train‘, but what AEMET says is that, during the bridge (after some persistent rain in the north), what we are going to have is a predominance of sun and higher than normal temperatures. How is it possible? What dark atmospheric dynamics are conspiring to give us good weather on the Constitution Bridge? The rhombus phenomenon. That’s what he called it meteorologist Luismi Pérez on Cadena Ser and the truth is that the explanation is so visual that it can help us understand what is happening. “Rhombus” is a colloquial way of defining an isobaric configuration that diverts the cold to North America and gives stability, little rain and high temperatures to our country. And what does it take for that to happen? Four masses of air are needed to achieve this: a robust anticyclone in Newfoundland and Greenland another anticyclone in the Mediterranean area a storm in the Azores and another in the Scandinavian peninsula In the image above it is still difficult to see, but arranged on the isobar map “they form an approximate figure of a rhombus.” Why it is important. Meteorologically speaking, the rhombus describes a type of atmospheric block very characteristic: a reconfiguration of the polar jet and the trajectory of the storms that takes us away from the coldest scenarios. Yeah the face is the train of stormsthis is the cross: short periods of stability and good temperatures. What we can expect in the coming days. As Pérez explainedthis rhombus “makes” the very cold air accumulated in Greenland slide towards the west; that is, towards North America, instead of falling on Europe. In addition, Spain (being under the influence of the Azores storm and the Mediterranean anticyclone) is assured of westerly and southwesterly winds, which are more temperate and pleasant. What we can expect in the long term. Because in the background there is something more serious: changes in the atmospheric circulation of the Atlantic Ocean. That is to say, the increase in the number of episodes of stability, clear skies and absence of fronts in autumn and winter. Something that can be perceived as “good weather”, but that aggravates the structural drought and complicates water, agricultural and energy planning. Luckily, it looks like it won’t last long. Just enough to let us enjoy the bridge Image | ECMWF In Xataka | The most beautiful, exciting and hopeful thing about November has come out of England and it is a weather forecast
