Monthly mean maps for precipitation and temperature (observed and anomaly) with a summary of the monthly meteorological situation


This analysis is based on observational data of precipitation and temperature. For a monthly analysis based on ERA5 reanalysis, please see the Climate bulletins produced by Copernicus Climate Change Service

Meteorological situation for December 2019

Figure 1. Accumulated precipitation [mm] for December 2019.
Figure 1. Accumulated precipitation [mm] for December 2019.
Figure 2. Precipitation anomaly [%] for December 2019, relative to a long-term average (1990-2013). Blue (red) denotes wetter (drier) conditions than normal.
Figure 2. Precipitation anomaly [%] for December 2019, relative to a long-term average (1990-2013). Blue (red) denotes wetter (drier) conditions than normal.
Figure 3. Mean temperature [°C] for December 2019.
Figure 3. Mean temperature [°C] for December 2019.
Figure 4. Temperature anomaly [°C] for December 2019, relative to a long-term average (1990-2013). Blue (red) denotes colder (warmer) temperatures than normal.
Figure 4. Temperature anomaly [°C] for December 2019, relative to a long-term average (1990-2013). Blue (red) denotes colder (warmer) temperatures than normal.

The meteorological situation in December 2019 was characterised by a lower than normal monthly mean surface pressure centred in the northern parts and extending over the majority of the EFAS domain reflecting the recurring occurrence of low-pressure systems, whereas it was higher than normal in the western African parts of the EFAS domain. Monthly precipitation totals were below normal mainly in the eastern and southern parts as well as in the northwest and centre of the EFAS domain. The highest positive monthly precipitation anomalies were observed around the Mediterranean region. Monthly mean air temperatures were above normal over the whole EFAS domain except for Iceland.

 

At the beginning of December, three low-pressure systems were active in the EFAS-domain: one located over the northwestern parts of the Iberian Peninsula, one over the Black Sea and the third north of Scandinavia. A high-pressure system was located over central and southeast Europe while another high-pressure system was located over the Atlantic Ocean. The low-pressure system over the Black Sea caused intense precipitation eastward and southward of the Black Sea with the highest daily totals at the southeastern coast. It was replaced by the eastward moving high-pressure system, located before over southeast Europe. The low-pressure system north of Scandinavia moved slowly eastward and other low-pressure systems over the Atlantic influenced this region, therefore many days with precipitation occurred at the Scandinavian west coast. The low-pressure system at the Iberian Peninsula moved around in this region and caused intense precipitation events at the Spanish and French Mediterranean coasts.

 

In the following days, the remaining high-pressure systems weakened or moved to the Azores, so most of the EFAS-domain was influenced by low-pressure systems causing large-scale precipitation. A weak low-pressure system at the eastern Mediterranean region caused heavy precipitation in Israel and Lebanon. Another low-pressure system developed over northern Africa, moved to the central and eastern Mediterranean region and caused intense precipitation at the Balkan Peninsula. At the same time, a large low-pressure system was located over Scandinavia and caused high precipitation totals in Great Britain and Ireland as well as in southern Norway. In addition, another low-pressure system intensified as it moved from Greenland via Iceland to the region between Norway and Greenland and caused intense precipitation in Portugal, Spain and France. Then again, yet another low-pressure system moved from Greenland to Great Britain and Ireland and caused the formation of a low-pressure system over the Adriatic Sea with intense precipitation at the eastern coast. A cold air advance at the eastern Atlantic was related to the low-pressure system over Great Britain and Ireland and initiated the development of a low-pressure system over northern Africa, which later caused intense precipitation in the central Mediterranean region. This was followed by a low-pressure system which moved from Newfoundland to the region westward of Great Britain and Ireland and caused intense precipitation at the Iberian Peninsula. Within the next days, a low-pressure system formed over the Gulf of Lyon and moved eastward causing heavy precipitation in southern France, northern Italy and Croatia. In the days until the end of December, the eastern Mediterranean region was influenced by low-pressure systems causing heavy precipitation especially at the coastal regions. The remaining EFAS domain was influenced by high-pressure systems or weak pressure gradients, except for Scandinavia in the last three days of the month.

 

In December 2019, the highest precipitation totals were observed in the northwest of the Iberian Peninsula, the Mediterranean east coast as well as the Scandinavian west coast (Figure 1). No or only very little precipitation fell in parts of northern Africa and around the Caspian Sea. More than normal precipitation was observed in many parts of southwest and northeast Europe and the eastern Mediterranean region (Figure 2). Less than normal precipitation fell in Iceland, central Europe, westward and eastward of the Black Sea, the western parts of northern Africa and the southeast part of the EFAS domain.

 

The monthly mean air temperature ranged from –20.7°C to 21.3°C with the highest values in the southern parts and lowest in the northern and mountainous parts of the EFAS domain (Figure 3). Air temperature anomalies ranged from -3.7°C to 8.4°C (Figure 4). Monthly mean air temperature values were above the long-term mean in the majority of the EFAS domain and only in Iceland below the long-term mean.