Summer 2009 forecast for Europe
Summary. In the summer of 2009, temperatures over much of Europe are forecast to be above average. The CFs for above normal temperatures are higher for central Europe. In Scandinavia, summer temperatures will probably be near average, somewhat colder than normal on the north and warmer than normal on the south. In the eastern Mediterranean, summer temperatures are expected to be below the average for the past 20 years. Although much of Europe is likely to be warmer than average, no heat waves are expected. Precipitation is forecast to be close to average.
Discussion
Temperature
In the summer of 2009, temperatures over much of Europe are forecast to be above average. The CFs for above normal temperatures are higher for central Europe. This conclusion is supported by rule 389, which is based on the QBO, and rule 487, which links spring precipitation pattern to summer temperatures in central Europe. Also, there is a bias toward warmer than normal temperatures in central Europe after a cold ENSO event in the equatorial Pacific (rule 292). Warmer temperatures in northern Russia are supported by rule 503.
In Scandinavia, summer temperatures will probably be near average, somewhat colder than normal on the north and warmer than normal on the south. While some rules suggest that temperatures there will increase compared to the previous summer (rules 392 and 393), other rules (e.g., rule 395) suggest the opposite.
In the Mediterranean region, summer temperatures are expected to be below the average for the past 20 years. This conclusion is based both on temperature extrapolation and spring precipitation pattern. The temperatures, however, will probably remain above or near the average for the base period of 1971-2000. A substantial difference between the average temperature for the past 20 years and climatological normals (1971-2000) is a result of a climate regime shift toward warmer temperatures that occurred in the late 1980s. Rule 187 suggests a warmer than normal temperatures in the central Mediterranean.
Although much of Europe is likely to be warmer than average, no heat waves are expected this summer (rules 244 and 267). Also, the AMO index has substantially declined in recent months, which also lowers the probability of heat waves.
There is no consistency among climate model forecasts for this summer. Thus, the CFS model predicts a colder than normal summer in western Europe and the Mediterranean, while the IRI multi-model probability forecast calls for a warmer than normal summer over most of Europe, with the highest probability over the eastern Mediterranean. The latter region is forecast to be colder than normal in the ECPC model. According to the U.K. Met. Office model, much of western Europe temperatures are likely to be near average. (A more recent run of the U.K. Met. Office model indicates warmer than normal temperatures almost over entire Europe.)
Precipitation
Precipitation is forecast to be close to average, because of the mixed signals for different rules. For example, rule 321 suggests drier than normal conditions in northwest Europe wetter than normal conditions in the eastern Mediterranean due to SST anomaly pattern in the North Atlantic. However, rule 311 indicates a possible precipitation deficit in the latter region and above normal precipitation in central Europe and southern Scandinavia. The UK Met. Office did not issue a precipitation forecast for this summer, saying that “at this stage forecast signals are too weak to provide an outlook for summer rainfall”. According to the CFS model, much of Europe is going to be wetter than normal.
