Climatic conditions over the territory of Russia.

By and large, the year 2008 was very warm in Russia. The anomaly of mean annual air temperatures averaged over the Russian territory was 1.9° C; this value ranks second among the values obtained throughout the period of observations (Fig.1).

Figure 1. Anomalies of mean annual air temperatures averaged over the Russian territory, 1939-2008 (against 1961-1990 normals)

Anomalies of mean air temperatures were positive for all the seasons (Fig.2), with the autumn air temperature anomaly attaining 2.1° С (the second value on record that was only exceeded in 2005).

Figure 3 shows anomalies of mean winter air temperatures (December – February) averaged over quasi-homogeneous climatic regions ( I – northern European Russia and northern Western Siberia, II – northern Eastern Siberia and northern Yakutia, III – Chukotka and Kamchatka, IV – central and southern European Russia, V – central and southern of Western Siberia, VI – central and southern Eastern Siberia, VII – Far East). In region 1 (northern European Russia and northern Western Siberia), this anomaly attained a record-breaking value, 5.9° С.

Figure 2. Anomalies (deviations from 1961-1990 averages) of mean seasonal air temperatures averaged over the Russian territory

Figure 3. Anomalies (deviations from 1961-1990 averages) of mean winter air temperatures (December – February) averaged over quasi-homogeneous climatic regions, 1939-2008

In January, the Russian territory experienced air temperature anomalies -9 to +12° С. January was very warm in the north of the country, most of the Yakutia-Sakha Republic, the Amur Region, and the southern Khabarovsk Territory. In the east of the Nenets Autonomous Area and the north of the Komi Republic, mean monthly air temperature anomalies were higher than 10° С. Maximum temperature anomalies (higher than 12° >С) were recorded on the Arctic coast. These large anomalies are caused by significant deviations from climatic distribution of the surface pressure field. The Iceland minimum, which was slightly shifted northeastwards, was considerably deeper than its normal values, the same being true for the trough going from the Iceland depression along the northern coast of Eurasia. Throughout January, the Atlantic cyclones passed over the northern seas around Eurasia contributing to the formation of warm and wet air masses in the coastal regions. In southern European Russia and southern Western Siberia, on the contrary, it was very cold. Such cold weather was due to the fact that the Siberian anticyclone moved southwest of its climatic position, became more intensive, and covered larger areas than it normally did forming a common heygh with the Azores anticyclone. In the first ten-day period, abnormally cold weather with mean daily air temperatures 7-15° С below normal was recorded in Central Chernozem Regions. In the Volgograd Region, the Stavropol Territory and the Chechen Republic, minimum air temperatures attained -25…-28° С. In the south of Western Siberia, severe frosts (-35…-40° С) were recorded in the second ten-day period of January. On 12-19 January, in some places of the Tomsk and Kemerovo Regions and the Altai Territory, air temperatures dropped as low as -42° С. On these days, the mean daily air temperature was 7-16° С below normal. In some areas of the Krasnoyarsk Territory, the Irkutsk Region and Transbaikalia, the air temperature attained -46…-50° С.

In European Russia, except the Black Sea coast, and in most of Siberia, mean February temperatures were above normal. Maximum anomalies (higher than 10° C) were recorded in southwestern Yakutia. As for European Russia, the warmest weather in February was recorded in the west, where mean monthly air temperatures were 6-7° С above normal. In Eastern Siberia, a warm island formed over Evenkia. Mean monthly temperature anomalies at the centre of the island were 8-9° С. A vast water saturation zone extended from the western borders, through northern Central and Volga-Vyatka Regions, to the Southern Urals. The Northwestern Region, the southwestern Arkhangelsk Region and the Southern Urals received precipitation that was more than twice as much as mean monthly values. At the beginning of the second ten-day period, the Sverdlovsk Region and Bashkortostan experienced severe snow storms, with wind speed attaining 24 m/s and visibility being as poor as 300-500 m, and with snow drifts on the roads. The southern Far East suffered from substantial precipitation deficit. Some of the stations in the Maritime Territory and the Amur Region recorded no precipitation. This situation persisted here for two months.

By and large, spring temperatures over the Russian territory were higher than the long-term average. The seasonal air temperature anomaly, averaged over the Russian territory, ranked fourth for the period of record. In the Far East (region VII), a positive anomaly of the mean seasonal air temperature averaged over the region attained a record-breaking value, 2.8° С (Fig.5). In central and southern European Russia (region IV), the spring air temperature anomaly in 2008, 2.2° С, ranked third for the period of record.

Figure 5. Anomalies of mean spring air temperatures averaged over quasi-homogeneous climatic regions, 1939-2008

Mean monthly air temperatures in March were 1-2° С below normal in northern European Russia and northern Western Siberia. On the rest of the Russian territory, March was very warm. As for European Russia, maximum anomalies of mean monthly air temperatures were recorded in the mid-Volga Region and the Southern Urals (higher than 7° С). Warm weather in these regions was accompanied by a large amount of precipitation (more than two monthly averages). This resulted in torrential spring floods on the Buzuluk, Tersa and other rivers in the Volgograd Region. In the east of the country, a large warm island formed at the centre of which, above the eastern Yakutia-Sakha Republic, mean monthly air temperature anomalies were higher than 10° С. In the southern Khabarovsk Territory, mean monthly air temperature anomalies were 7-8° С. High temperatures in these regions were accompanied by a large amount of precipitation. In the vicinity of Yakutsk and in the Jewish Autonomous Area, precipitation amount was three times as high as the monthly average.

In April, the largest temperature anomalies were recorded over European Russia, where (except the northern Kola Peninsula and the northern Komi Republic) mean monthly air temperatures were above normal. Very warm weather was recorded in the second half of April in the central regions, where normal values were exceeded by 4-5° С. Significant precipitation deficit was recorded in the southern Far East (western Amur Region, eastern Maritime Territory and southern Sakhalin) against the background of positive temperature anomalies (3-4° С).

In May, the division between negative and positive anomalies in the temperature field coincided with the border between the two continents. In European Russia, mean monthly temperatures were below normal. In some of the regions, new daily air temperature minima were recorded. Nearly the whole of the territory east of the Urals experienced warmer weather than the long-term average. In many regions of Siberia and the Far East, new daily air temperature maxima were recorded. In late May, air temperatures rose to +25° in Yakutia and to +35° in southern Siberia.

By and large, summer over the Russian territory was warmer than the long-term average. Mean seasonal air temperatures were above normal in all quasi-homogeneous regions (Fig.6). It was especially warm in the east of the country. Summer in the Far East (region VII) was the hottest throughout the period of record. In central and southern Eastern Siberia, mean summer air temperatures were 1.8° С above long-term average and ranked third in the period of record.

Figure 6. Anomalies of mean summer air temperatures averaged over quasi-homogeneous climatic regions, 1939-2008

In June, negative temperature anomalies persisted in European Russia. In the first ten-day period, ground and air frosts were recorded everywhere, except the Southern Federal Area. In some regions (Bashkortostan and Northwestern Region), surface soil temperatures dropped to -6° С. June was very warm in Eastern Siberia and southern Yakutia. A large warm island formed over the southern Yakutia-Sakha Republic, with mean monthly air temperature anomalies at the centre of the island being higher than 6° С. Very hot weather, predominantly without precipitation, was also prevailing in the Amur Region and the southern Khabarovsk Territory. These weather conditions caused railway accidents and numerous forest fires. The city of Khabarovsk was wrapped with dense smog from forest fires that gave rise to poor visibility and unfavorable ecological conditions in the city. As for precipitation, European Russia experienced local thundershowers; these were particularly heavy in the Upper Volga Region and in Northern Caucasia. During showers in the republics of Northern Caucasia, as well as the Krasnodar and Stavropol Territories, precipitation amount was 75-96 mm in one to three hours. Showers were accompanied by heavy thunderstorms, hail (to 25-40 mm in diameter) and squally wind. In Dagestan, heavy rains caused numerous mudflows of different size. At the same time, the Orenburg Region and the western Altai Territory experienced hot winds. In the third ten-day period, soil drought began in the western Altai Territory. Substantial precipitation was missing for 16-18 days.

No significant mean monthly temperature anomalies were recorded in July, although individual regions experienced significant short-time anomalies. Very hot weather was observed on 14-22 July in southwestern Yakutia, where diurnal temperatures attained 30° С. Hot weather and precipitation deficit gave rise to numerous forest fires in the southern Khabarovsk Territory. On 15 July, owing to forest fires, the city of Khabarovsk was wrapped with dense smoke, with visibility being less than 50 m. On the last days of July, the southern and southwestern Altai Territory experienced strong heat, with maximum air temperature being 35-42° С. Values recorded by some of the meteorological stations were higher than absolute temperature maxima for these days. In some of the Regions, long-term precipitation maxima were also exceeded (Fig.7).

Figure 7. Precipitation total in July 2008 against normal. Insets show monthly precipitation total series in July and daily precipitation in 2008 at meteorological stations Moskva, Chertkovo, Kislokan, and Srednekolymsk

Very rainy July was reported to be in the Central Region, the mid-Volga Region, the Orenburg Region, the southwestern Central Chernozem Region, and the northwestern Rostov Region (20-300% of monthly average). In the North Caucasian Region, heavy thunderstorm rains, in places accompanied by large hail (20-30 mm in diameter), were observed throughout July. In Transbaikalia, heavy thunderstorm rains were often accompanied by squalls as strong as 23-30 m/s. Particularly unfavourable weather conditions were recorded in late July: showers bringing 33 to 70 mm of precipitation, in places accompanied by hail as large 2-40 mm, with wind speed to 33 m/s.

August was warm over most of the Russian territory. A zone of negative anomalies of mean monthly air temperatures extended from the Kola Peninsula, through the central regions of Western Siberia and the Krasnoyarsk Territory, to Baikal.

Hot winds were observed in the Altai Territory by the end of the first ten-day period (maximum air temperature rose to 31-38^оС, minimum air humidity decreased to 18-30%, with wind speed of 10-16 m/s). Very hot and dry weather set in the second half of August in southern European Russia. In the Central Chernozem Region, from 13 to 19 August, diurnal temperatures rose to 35-38^оС. In combination with substantial precipitation deficit, this produced extreme fire risk. In the Rostov Region, most of the Krasnodar Territory, Adygeya, the northern and eastern Stavropol Territory, and the steppe zone, maximum air temperatures were above 30^оС for 24-25 days, attaining on separate days 36-40^оС. Effective precipitation (more than 5 mm) was missing 30-31 days.

The autumn in 2007 was also abnormally warm, particularly in regions IV and V, where positive anomalies in the ordered series ranked third and second, respectively (Fig. 8).

Figure 8. Anomalies of mean autumn air temperatures averaged over quasi-homogeneous climatic regions, 1939-2008

September was characterized by moderately warm weather in the southern Far East that was accompanied by insufficient precipitation (30-70% of monthly average). Low water persisted in the lower Amur river. Maximum water level in September was 105 cm. Such low water levels in the lower Amur have not been recorded since 1921. The September of 2008 in European Russia will be remembered by intensive heat and cold waves. It should be noted that the same regions alternately received both extremely cold and extremely warm air. For example, on 11 September, thermometers in the Voronezh city showed record-breaking temperature, 30.7°, and in the neighbouring city of Tambov, on 27 September, air temperature dropped to a record-breaking value, -2.6° .

In the Magadan Region, Chukotka and Kamchatka, the weather was considerably warmer throughout the month, as compared with normal values. In the cities of Magadan and Petropavlovsk-Kamchatski, as well as in other settlements of these regions, daily air temperature maxima were exceeded. Even in late September, diurnal air temperatures were above 15-16° , which is abnormal for this time of the year.

By and large, October over the Russian territory proved to be the warmest throughout the period of record. The air temperature anomaly, averaged over the Russian territory, was 2.9° С. Positive temperature anomalies at individual stations did not reach record-breaking values (maximum anomalies were no higher than 6° С), but their coverage (nearly the whole of the Russian territory) is responsible for the October record-breaking value in 2008. In most of European Russia, warm weather in October was accompanied by insufficient precipitation. In the Saratov and Orenburg Regions, owing to significant precipitation deficit combined with high air temperatures, fire risks lasted as long as the second ten-day period of October. At this time, Transbaikalia received very much precipitation, with monthly average in places being exceeded by two to three times. Early in the third ten-day period, heavy snowfalls produced snow cover as deep as 3-35 cm; snowstorms occurred with wind speed to 18-22 m/s and visibility as poor as 500 m. Heavy snowstorms also took place on Taimyr and in Khakassia. In the Amur Region and the central Khabarovsk Territory, monthly precipitation total was also two to three times as high as climatic normal.

November proved to be warm nearly over the whole of the Russian territory. Over most of the country, mean monthly air temperatures were above climatic normal for two consecutive months. Abnormally warm weather prevailed over European Russia, particularly in the Urals, where mean monthly air temperature anomalies attained 6-7° С. In Western Siberia, the island of maximum anomalies (more than 8° С) formed over the northern Omsk Region. Central regions of Sakhalin received precipitation that is more than twice as much as monthly normal. Most of this precipitation was brought to Sakhalin on 8-11 September by a deep southern cyclone. Precipitation was accompanied by windstorm as strong as 25-32 m/s, with wind gusts reaching 40-41 m/s.

In December, two intensive heat islands formed over the Russian territory; these were recorded over northern regions of European Russia and Western Siberia and over continental regions of the Magadan Region and Chukotka. Here mean monthly air temperature anomalies attained 10° С and at a number of stations record-breaking values of mean monthly temperatures were observed. Heat islands were separated by the cold area located over western Yakutia (Fig.9).

Figure 9. Air temperature anomalies in December 2008. Insets show mean monthly and mean daily air temperatures in December 2008 at meteorological stations Marresalya, Omolon and Olekminsk

Snow state over the Russian territory in the winter of 2007-2008 was studied from regular snow observations at 600 Russian meteorological stations.

The number of days with snow covering more than 50% of the area around a meteorological station was used to estimate the snow cover duration (Fig.10).

Space distribution of snow cover duration anomalies over the Russian territory in the winter of 2007-2008 shows several islands of positive and negative anomalies. Over a large area covering extreme northeastern regions of European Russia and most of Western Siberia, snow cover duration was substantially shorter than the long-term average. In the southern Tyumen Region, snow remained 20-40 days less than it usually did. This island is, to a greater extend, connected with higher temperature conditions, particularly in spring, while the island of negative anomalies in the southern Far East is related not only to very warm beginning of winter, but also to an extremely low amount of winter precipitation. In the Maritime Territory, snow cover only set in December and in the southeast of the Territory, in the third ten-day period of December. In western and southwestern European Russia and the Central Urals, snow also remained not as long as it usually did. An island of small negative anomalies also formed over Chukotka.

Most of Eastern Siberia showed positive anomalies of the number of days with snow covering more than 50% of the area around a meteorological station. Snow cover appeared in the northern regions as early as the second half of September and in the southern regions it was recorded in the first ten-day period of October. Only individual regions of Yakutia and the northwestern coast of the Sea of Okhotsk showed snow cover duration anomalies of more than 20 days.

Figure 10. Anomalies of the number of days with snow covering more than 50% of the area around a meteorological station in the winter of 2007-2008 (as against mean long-term values for the period 1961-1990). The insets show: а) early dates of snow covering more than 50% of the area around a meteorological station and mean daily values of the extent of snow cover on the territory around meteorological stations Ishim (28573) and Okhotsk (31088).

Space distribution of maximum snow height anomalies over the Russian territory in the winter of 2007-2008 exhibits prevailing positive values (Fig. 11). In the Urals, snow height was above normal due to very much precipitation that occurred in February and March. In northern Western Siberia, owing to very warm October, snow was delayed, but due to a large amount of snow in November, snow height was well above normal. The largest contribution to positive snow height anomalies in the northern Krasnoyarsk Territory was made by extremely warm weather that was observed in this region in February and March (Figs 11 and 12).

Figure 11. Maximum snow height anomalies in the winter of 2007-2008 (as against mean long-term values for the period 1961-1990). The insets show daily means of air temperature, snow extent around a meteorological station and snow height, and daily precipitation totals at meteorological stations Turukhansk (23472) and Ust’-Kamchatsk (32408).

Intensive Atlantic cyclones penetrated far inland bringing warm saturated air. In February and March, these regions received precipitation that was more than twice as much as monthly normal. In Chukotka, positive snow height anomalies are produced by gradual snow accumulation throughout the long winter period typical of these regions, rather than a large amount of precipitation. Heavy snowfalls in January and February caused above-normal snow height in Kamchatka (Fig.11).

Figure 12. Maximum snow height in the winter of 2006-2007. The insets show mean daily snow heights and daily precipitation totals at meteorological stations Talon (31092) and Vorkuta (23226).

According to meteorological stations on the coast of the Sea of Okhotsk, maximum snow height at the center of maximum anomalies was attained in late April, following heavy snowfalls (Figs 11 and 12).