Europe Mars Bulletin Vol. 20 No.12

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Reports » Europe Mars Bulletins » Europe Mars Bulletin Vol. 20 No.12

19 December 2012

Winter Cereal Hardening is Progressing Well

The last dekad of November presented milder thermal conditions than usual in late autumn. Weather conditions changed in the first dekad of December and real winter conditions established across Europe. Severe and frequent frost events ruled the continent. Excessive precipitation was recorded for the British Isles and in the northern Mediterranean, though precipitation was abundant in most of Europe.

Currently thick and contiguous snow covers not only northern and eastern Europe, but also central Europe and the Balkan Peninsula. According to our simulations winter cereals hardening is progressing well and so far no frost kill damage has been simulated.

Agro-Meteorological Overview

The last dekad of November presented milder thermal conditions than usual in late autumn. Weather conditions changed dramatically in the first dekad of December and real winter conditions established across Europe. Severe and frequent frost events ruled the continent. Excessive precipitation was recorded for the British Isles and in the northern Mediterranean, though precipitation was abundant in most of Europe. Currently thick and contiguous snow covers not only northern and eastern Europe, but also central Europe and the Balkan Peninsula.

Observed Temperatures

During November the temperature showed significant fluctuation, but the overall seasonal decreasing of temperatures was moderate and less than climatologically expected. The last dekad of November was warmer than usual for most of Europe with the exception of the western part of the Iberian Peninsula, some regions in Maghreb and the British Isles. Positive thermal anomalies from +4 to +6°C compared to the average temperature manifested in a wide strip between the Adriatic and northern Baltic regions. In the last days of November an arctic cold air intrusion started causing sharp decreases in temperature and consequently below average thermal conditions characterized the first dekad of December for most of Europe, with the exception of south eastern Europe including eastern Mediterranean. Also the Black Sea area and southern Russia remained warmer than usual.

After 6 December harsh winter frosts occured in central Europe. The temperature decreased below -10°C between the Baltic and Adriatic Sea, but in Poland, the Czech Republic and Slovakia as low as -15°C- -18°C minimum values were recorded. Only the southern coastline of the Atlantic and the Mediterranean Sea remained frost free.

The cold spell of December brought the risk of winter kill damage. To evaluate the risk a frost kill model is run. Our model simulates the hardening index of a crop and thus provides an estimate of the low-temperature tolerance of cereals, taking into account plant physiology (hardening process, i.e. transformation of the cellular starch into glucose, thereby raising the freezing point of the cellular liquids). In our model a fully hardened winter cereal is considered to tolerate –18°C.

The results of model runs based on observed weather conditions up to 10 December 2012 indicate no or slight low-temperature tolerance of winter cereals along the shore of southern Europe. Crops achieved medium frost tolerance in France, Benelux countries, the UK, central Spain, northern Balkan, Turkey, eastern Ukraine and southern districts of Russia. Winter crops are almost or fully hardened in an area from Germany to Belarus and western Ukraine just as the northern agricultural zones of Europe. No frost damages are simulated until now on the basis of our frost kill analysis. Taking into account the medium range weather forecast until 26 December the period is simulated to remain free of damage.

The active temperature sum (Tbase=0°C) for the considered time-period indicates characteristically +20- +50 growing degree days surplus eastward of Poland- Croatia l with a remarkable local maximum close to the Sea of Azov and further with decerasing intensity towards the Caspian Sea. The above average thermal conditions on these territories favoured the development of winter crops.

Observed Precipitation

The precipitation amount from 21 November until 10 December was above average in Germany, Bulgaria, Romania, Turkey, Belarus, most of Ukraine and large areas of central Russia. Excessive precipitation surpassed 150 mm in Middle England, in some regions on the western and northern shore of the Iberian Peninsula as well as in the Alpine region, northern Italy, and along the western coast of Tyrrhenian, Adriatic, Ionian and Aegean Sea. These areas received a rain surplus of over 75 mm as compared to the long term average.

Favourably plentiful rain was also recorded in Morocco and Algeria. Hardly any precipitation (<10 mm) was measured in eastern Spain, in western Scandinavia, and in smaller districts of Austria, Hungary, Slovakia and Poland.

Primarily most of Scandinavia and the northern areas of Russia were snow covered, but starting the last days of November, more and more thick snow covered central Europe. On 10 December snow covered not only most of Scandinavia, but also areas from eastern France and Germany to Russia including Poland, central Europe, northern Italy, the Balkan Peninsula and Ukraine as well as Turkey. Snow depth has a significant spatial variability, but reaches characteristically 5-15 cm on the lowlands and exceeds 20 cm on given regions of the Balkan, Romania and Ukraine.

Weather Forecast for the Coming Days: 13 December to 22 December

Colder than usual weather is expected in eastern and northern Europe, moderate frost events in central Europe. Abundant rain is forecast for the western half of Europe and in Turkey.

Forecast Temperatures

Over the next few days, Spain, France, Benelux and western Germany will experience cumulated active temperature (Tbase=0°C) above the long term average (by 20 GDD), whereas in northern Italy, and locally in Mediterranean areas lower than usual accumulation of temperatures is foreseen. In western Europe and south of Maghreb the mean temperatures could exceed the seasonal values by +2 - +4°C. Colder than usual weather is forecast for eastern and northern Europe and also for northern Italy. Severe frost events (Tmin<-20°C) will be concentrated in northern Russia, Belarus and northern Ukraine. Spain, Portugal, southern France, Ireland and southern Italy are forecast to be frost free.

Forecast Precipitation

Low pressure over the Atlantic is going to dominate the weather over western and central Europe. Therefore abundant precipitation is forecast around the Atlantic coast, mainly in the United Kingdom, Ireland, Spain, Portugal and France, but also in western Germany, the alpine region, northern Italy and in Turkey. In these areas cumulated rainfall will exceed long term average (LTA) by 50 mm, and locally the total amount of rainfall may exceed 50 mm. In central Europe, three or four days of precipitation are expected, with cumulated values not exceeding 30 mm, which could create a few centimetres of snow cover (mainly in Germany, Poland, the Czech Republic, and Romania). During the following three to four days some snow is expected also in northern Italy and in the Balkan Peninsula. Very scarce precipitation is expected in Russia, Belarus and central Ukraine (all mainly as snow).

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