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SEASONAL CLIMATOLOGICAL BULLETIN FOR SERBIA

Spring 2013

Belgrade June 12 2013

Department for climate analysis and forecast, information and training

web: http://www.hidmet.gov.rs

mail: office@hidmet.gov.rs

QF-E-003

Republic Hydrometeorological Service of Serbia

Kneza Viselslava 66

11000 Belgrade

Republic of Serbia

In most of Serbia, spring 2013 was marked by warm weather and precipitation sums above multiannual average

Analysis of the 2013 spring season compared to 1961-1990

base period for Serbia

Temperature

During spring 2013, mean air temperature ranged from 11.3 °С in Dimitrovgrad up to 13.6 °С in Belgrade and in the mountain areas from 3.7 °С on Kopaonik up to 8.5 °С on Zlatibor (Figure 1).

Mean air temperature anomalies from the normal1 for the 1961-1990 base period during spring were in a range from 0.4 ºC in Sombor up to 1.6 ºC in Kursumlija and in high-lying areas from 0,7 °C on Crni Vrh up to 2.3 °С on Kopaonik (Figure 2 ).

1Term normal refers to climatological standard normal, that is, the average value of a particular climate element, calculated for the period from January 1, 1961 to December 31, 1990

Figure 1. Spatial distribution of mean seasonal air temperature (C°) during spring 2013

Figure 2. Mean seasonal air temperature anomaly from the normal for the 1961-1990 base period during spring 2013

According to the percentile2 method, mean air temperature during spring was in the categories warm and very warm in most of Serbia. (Figure 3).

According to the tercile method, mean air temperature during spring was above average across almost the entire country. (Figure 4).

The highest daily air temperature during spring 2013, measuring 34.0 °С, was recorded in Banatski Karlovac on April 20.

The number of summer days, with maximum daily air temperature exceeding 25°С, ranged from 17 in Sombor and Palic up to 26 in Negotin, Curpija, Leskovac and Zajecar. Simultaneously, the number of summer days, ranging from 3 to 6 was observed on the mountains, Crni Vrh and Zlatibor, respectively. Highest deviation from the average number of summer days was registered in southwestern and parts of central Serbia (Figure 5).

All of Serbia, apart from the mountain areas, experienced tropical days with temperatures exceeding 30C°, ranging from 2 in Vranje and Palic up to 10 in Leskovac.

2nth percentile of a variable refers to the value of the observed variable below which there is n percent of data previously arranged in an ascending order

Figure 3. Assessment of the air temperature in Serbia during spring 2013 using the percentile method compared to the 1961-90 base period

Figure 4. Assessment of the air temperature in Serbia during spring 2013 using tercile method compared to the 1961-90 base period

Two tropical nights, with minimum air temperature higher than 20C° were recorded in Belgrade while Banatski Karlovac and Veliko Gradiste observed one each.

The number of frost days, with minimum temperature lower than 0 °С, ranged from 10 in Belgrade, Kragujevac and Nis up to 16 in Sombor, Dimitrovgrad and Zajecar. On the mountain areas the number of the observed frost days ranged from 22 on Zlatibor up to 40 on Kopaonik. The highest negative deviation of the average number of frost days was registered in western Serbia. (Figure 6).

The number of ice days, with maximum air temperature lower than 0˚ was recorded at 5 stations, (up till 2 days), whereas in the mountain area that number ranged from 3 on Zlatibor up to 13 on Crni Vrh.

The lowest spring air temperature, measuring -18.4 °C was observed on Kopaonik Mountain on May 17.

During most of the spring time, Belgrade observed maximum and minimum air temperature above multiannual average. (Figure 7).

Three-month course of mean daily air temperature in Belgrade, Kopaonik and Zajecar during spring 2013 is shown in Figures 8, 9 and 10.

Figure 5. Deviation of the summer days during spring 2013 comapred to the 1961-1990 base period

Figure 6. Deviation of the frost days during spring 2013 compared to the 1961-1990 base period

Figure 7. Three-month course of mean, maximum and minimum temperature in Belgrade during spring 2013

Figure 8. Three-month course of mean daily air temperature in Belgrade during spring 2013

Figure 9. Three-month course of mean daily air temperature on Kopaonik Mountain during spring 2013

Figure 10. Three-month course of mean daily air temperature in Zajecar during spring 2013

Precipitation

During spring 2013, most of Serbia received above average precipitation compared to the normal for the 1961-1990 base period. Precipitation sums ranged from 93% in Kursumlija up to 205% in Palic compared to the normal (Figure 11 ).

According to the percentile method, precipitation totals during spring 2013 were in the rainy and very rainy category whereas in northwestern and southern Serbia those amounts were classified as the extremely rainy. (Figure 12).

Figure 11. Spatial distribution of precipitation sums expressed in the percentages of normal during spring 2013

Figure 12. Assessment of the precipitation totals using percentile method during spring 2013 compared to the 1961-1990 base period

According to the tercile method, precipitation sums were above average across most of Serbia. (Figure 13). Highest daily precipitation amount, measuring 70.5mm was recorded on Kopaonik Mountain on May 23. The new daily precipitation sum record for the spring season 2013, amounting to 59.6mm was set in Smederevska Palanka on May 23 thereby breaking the previous one of 59.1mm observed on May 22 1967. The highest deviation of the number of days with precipitation of 1mm and more was registered in northern Serbia, amounting to 11 days. (Figure 14).

Figures 15 and 16, for Belgrade and Palic show cumulative precipitation totals per month during spring 2013 compared to the average cumulative precipitation sums. During most of this period, precipitation sums significantly above average were recorded.

Figure 13. Assessment of the precipitation sums during spring 2013 using tercile method compared to the 1961-1990 base period

Figure 14. Deviation of the number of days with precipitation of 1mm and more during spring 2013

Figure 15. Cumulative precipitation sums for Belgrade

Figure 16. Cumulative precipitation sums for Palic

By the end of the spring season, the occurrence of the yellow rain was observed twice on the territory of Serbia. The synoptic situation analysis shows that the Balkans were under the prevalence of the deep cyclone with the center above west Europe. The position of this cyclone caused incursion of the air masses from the territory of Sahara brining rain containing sandcorns (yellow rain) to Serbia on May 17. The reccurance of the yellow rain was recorded on May 29. (Figure 18).

Figure 17 depicts 12-hour foreacast of desert dust aerosols.

Most of Serbia experienced several days with the occurrence of hail. Figure 18 shows hail observed in Belgrade on May 30 when atmospheric instability caused strong formation of the cumulonimbus clouds, expanding over Belgrade and producing severe weather: stormy wind, heavy rainfall and large hailstones.

Figure 17. Forecast of desert dust aerosols

Figure 18. „Yellow rain“ observed in Belgrade on May 30 2013

Figure 19. Hail observed in Belgrade on May 31 2013

Sunshine duration (insolation) During spring 2013, sunshine duration was within and somewhat above average across entire Serbia with values ranging from 95,2 in Zajecar and Palic up to 130.1 hours in Kursumlija (Figure 20). Insolation was in a range from 90% in Palic up to 135% in Kursumlija (Figure 21).

Heat waves Entire Serbia experienced one heat wave3 during spring 2013 while certain places even three heat waves where registered (Chart 1).

3 Heat wave, according to the percentile method, is a period during which maximum daily air

temperature is in the warm and very warm categories for 6 days or longer

Figure 20. Insolation during spring 2013, expressed in hours

Figure 21. Insolation during spring 2013, expressed in the percentages of normal

Chart 1.

Analysis of the 2013 spring season for Serbia compared to the

1971-2000 base period

Temperature During spring 2013, mean air temperature anomalies from the normal for the 1971-2000 base period ranged from 0.3 ºC in Sombor up to 1.5 ºC in Nis, Leskovac, Dimitrovgrad and Vranje, and when regarding mountains from 1.7 °С on Crni Vrh up to 2.0 °С on Kopaonik (Figure 22).

According to the percentile method, mean air temperature during spring 2013 was in the warm category in most of Serbia, whereas in Kursumlija and Sjenica it was classified as extremely warm. (Figure 23).

According to the tercile method, mean air temperature during spring 2013 was above average values in most of Serbia.

E Figure 22. Mean seasonal air temperature anomaly in Serbia during spring 2013 compared to the 1971-2000 base period

Figure 23. Assessment of the air temperature during spring 2013 compared to the 1971-2000 base period

Precipitation

All of Serbia received above average precipitation during spring 2013 compared to the 1971-2000 base period, with Kursumlija as an exception where below average precipitation was registered (during spring 2013 precipitation totals ranged from 96% to 213% compared to the normal) (Figure 24).

According to the percentile method, precipitation sums fell under the categories of rainy and very rainy in most of Serbia and extremely rainy in northern parts. (Figure 25). According to the tercile method, precipitation sums were above average values across entire Serbia.

Figure 24. Spatial distribution of precipitation totals expressed in percentages of normal during spring 2013 compared to the 1971-2000 base period

Figure 25. Assessment of the precipitation totals using percentile method during spring compared to the 1971-2000 base period

Analysis of the 2013 spring season for Serbia compared to the

1981-2010 base period

Temperature During spring 2013, mean air temperature anomalies from the normal for the 1981-2010 base period ranged from -0,1 ºC in Palic and Sombor up to 1,4 ºC in Kursumlija and on the mountains from 0,8 °С on Crni Vrh up till 1,4 °С on Kopaonik (Figure 26).

According to the percentile method, mean air temperature was in the following categories: normal, warm and very warm in Kursumlija, Sjenica and Kopaonik (Figure 27).

According to the tercile method, mean air temperature was above average in most of the country, and within the average in northern and parts of central Serbia.

Figure 26. Mean seasonal air temperature anomaly in Serbia during spring 2013 compared to the 1981-2010 base period

Figure 27. Assessment of the air temperature in Serbia during spring 2013 using percentile method compared to the 1981-2010 base period

Precipitation

Most of Serbia received above-average precipitation compared to the normal for the 1981-2010 base period (precipitation sums ranged from 94% to 202% compared to the normal) (Figure 28).

According to the percentile method, precipitation totals during spring 2013 were in the very rainy and rainy categories in most of Serbia (Figure 29). According to the tercile method, precipitation sums were above average values in almost whole of Serbia.

Figure 28. Spatial distribution of the precipitation totals expressed in the percentages of normal during spring 2013 compared to the 1981-2010 base period

Figure 29. Assessment of the precipitation totals using percentile method during spring 2013 compared to the 1981-2010 base period