Home › Review of winter 2009 in Europe
Review of winter 2009 in Europe
Temperature
The winter of 2009 was noticeably colder than the previous two winters. Temperature anomalies were generally below average in western Europe and above average in eastern Europe (Fig. 1). For example, mean winter temperature for the UK was 3.2 °C, which was 0.5 °C below the 1971-2000 average, making it the coldest winter since 1997.
Particularly cold spell occurred in late December - early January. Without that spell winter temperatures in western Europe would be close to normal.
This cold spell was associated with a negative NAO index, which reached the lowest values for the winter. During that period a high pressure cell settled in the area north of the British Isles (Fig. 2).
Atmospheric circulation around this cell led to an advection of cold Arctic and Siberian air. Anomalously cold temperatures were observed in the latitudinal belt between 35 and 55N (Fig. 3). Temperatures in Scandinavia, however, remained above normal.
The HDD forecast skill scores averaged for 8 European cities were 19, 84 and 64 relative to climatology, persistence and OCN, respectively.
Precipitation
Total amount of precipitation during the winter was below normal in northern Europe and above normal in the Mediterranean (Fig. 4). This pattern is more characteristic of a negative NAO phase. This winter, however, the NAO was in its neutral phase (see review for the North Atlantic). Cyclones were traveling north of Europe toward the Arctic and along their southern route toward the Mediterranean, while high pressure dominated over Scandinavia.
