When analysing our climate charts, a clear deviation in current temperatures (as compared to the long-term climatological average of 30 years) becomes visible. For example, while Murcia has a long-term average daily maximum of 17°C in February, temperatures in the past few days have risen to almost 30°C. Precipitation has also been sparse over the past few weeks, as the few precipitation bars in the weather archive show.
Even night-time cooling does not really seem to occur due to the high daytime temperatures. During the day, the surfaces heat up considerably due to the solar radiation, while at night, they release some of the stored energy back into the atmosphere in the form of heat. Barcelona, for example, would normally have night-time low temperatures of 4°C according to the climatological average. But the city is currently experiencing significantly higher night-time temperatures of up to 13°C, as shown in our heat maps. Both screenshots visualise city temperatures on February 6th, 2024. On the left, you can see the surface temperatures for midday, and on the right, there are the surface temperatures during the night (11 p.m. local time). The urban heat island effect (UHI) is recognisable, which is a phenomenon describing the fact that urban paved surfaces cool down significantly less than the suburban areas (or urban green spaces).
Stable high-pressure areas that accumulate warm air masses are responsible for the past and current high temperatures in Spain. High-pressure areas often bring cloud-free zones and higher temperatures. The sinking air masses inside a high-pressure system are adiabatically compressed and provide additional warming. Therefore, subsidence and a higher pressure level can be found at the base of the high-pressure area. If this high-pressure area remains relatively undisturbed and isolated, it can lead to long-lasting heat or a heat wave.
Furthermore, there is often no large-scale precipitation during a stable high-pressure situation. Small-scale convective precipitation, e.g. in the form of thunderstorms, is also usually absent due to the stable stratification of the atmosphere. The jet stream plays an essential role in the dynamics of weather conditions. In this case, the behaviour of the subtropical strong current band (jet stream) determines how stable and isolated individual high-pressure areas are. Our weather map shows the position and wind speed of the jet stream at 250hPa, i.e. at an altitude of around 10.5km, where the dynamic tropopause is located.
During the weekend (February 10th and 11th), the jet stream will change its shape from a relatively stable straight line to a meandering structure, which may indicate a change in the weather. With our wind animation, you can see an increasing destabilisation of the high-pressure area over the Mediterranean region in the coming days. At the weekend, parts of Central and Western Europe will then be under the influence of an area of low pressure moving from the Atlantic over Ireland towards the west coast of France.
The arrival of this low-pressure system also marks a temporary end to the heat and drought in Spain. A drop in temperature, as well as increasing cloud cover and precipitation, are expected. Increased wind speeds are also forecast in the Costa Verde (north coast of Spain). However, it remains dry even though some precipitation events are expected on Friday and Saturday.
