Air Temperature
From the first days of April, the southern regions of the ETR were in possession of extreme heat. At times, the thermometer readings rose above 25-30° to result in new daily temperature maxima. The air temperatures averaged for the first decade were 3-5° higher than normal in the south of the ETR, and close to normal in the northern and partly the central regions only. But in the second decade, abnormal heat came to the Russian North as well, with new air temperature maxima in the Arctic. And finally, the whole picture dramatically changed in the third decade. The heat survived in the south only where temperature maxima in excess of +30° were established again in the Volgograd and Astrakhan Regions as well as in the Krasnodar Territory and in the North Caucasus, whereas the weather in the northern and central regions became noticeably colder. The thermometer readings in the Moscow, Oryol, Belgorod, Kursk, Tambov and Lipetsk Regions and in the Volga region would drop to -3…-5° and below at night, and the temperature averages for the third decade turned out to be normal or even 1-2° lower than that.
Similar to the ETR, the first two decades in the Urals were warm. In the second decade, new temperature maxima were recorded in the Southern Urals and in neighbouring Bashkiria, the air temperatures rising above +25° sometimes. In the third decade, similar to the ETR again, colds came to this area, and temperatures below -5° were observed in Bashkiria and in the Chelyabinsk, Kurgan and Sverdlovsk Regions.
In most of Siberia, the weather was abnormally warm for almost the entire month. The air in the south of Western Siberia and of the Krasnoyarsk Territory, in Khakassia and in the Tomsk, Kemerovo and Irkutsk Regions heated up to +25° at some locations, updating the temperature highs ever achieved before. A disparity in temperature anomalies was observed between the northern and the southern regions of the Far Eastern Federal District where the weather in April was almost always warmer than usual in the Magadan Region and the Chukotka Autonomous District (with the decade-averaged temperature anomalies as high as +4-6° or larger), whereas the temperatures in the south, viz., in the Primorye and in the Khabarovsk Territory, were either close to, or lower than, the normal values in each decade of the month.
In the bottom line, the average air temperature across the ETR territory was higher than normal in April: two or more degrees higher in the south of the ETR, in the Urals, in Siberia and in the north of the Far East, and four or more degrees higher elsewhere in a large part of the ETR. The monthly-averaged temperature was approximately normal in the North-West Federal District, in the north of the Central one, and in the south of the Far Eastern Federal District.
As for Russia as a whole, the average air temperature in April measured over the European and Asian territories and in each federal district separately was outside the Top Ten highest values in the ranking list compiled since 1891.
Everywhere in East Asia (in particular, in China, Mongolia, Korea and Japan), the average in April temperature was above-normal. The normal values in the north and east of China were exceeded by 2-4°. Similar anomalies were observed in Korea, and somewhat weaker ones, +1…3°, in Mongolia and Japan. The south of China was the only region where the temperatures closely matched its normal values, and the south-east of the Yunnan province, where these values were observed against a negative background. At the end of the month, cold weather came to northern China: the air temperature in the Beijing area dropped by as much as 13° for a single day. New daily temperature minima were observed in a number of locations. But at the same time, the air in the south-eastern province of Guangdong heated to +33°, setting new daily temperature maximum. This April in China was the fifth warmest in the history of meteorological observations since 1891.
In South-East Asia, weak negative anomalies of monthly-averaged temperatures were recorded.
In the north of India and in neighbouring Pakistan, the weather was already as hot as in summer, with the temperatures in excess of +43-45° and their monthly-averaged anomalies reaching +3…5° or more. Such heat in these areas has never been seen in April before. On the other hand, the temperatures were close to normal in the centre of India, and weak negative monthly-averaged temperature anomalies were even observed in the extreme south. This April was the second hottest in the history of regular meteorological observations in India: the monthly-averaged temperature was higher in April 2010 only.
The weather in the Near and Middle East was also hot, with the monthly-averaged temperatures 2-4 or more degrees above their normal values. A sharp contrast of temperatures was apparent in Transcaucasia where hot air from the Plateau of Iran came at the beginning of the month, and the daily temperature maxima in Azerbaijan were overridden to exceed +30° in some places. However, cold air broke through to the Transcaucasian republics in the middle of April, and those maxima gave way to the record-breaking temperature minima in Armenia.
Heat prevailed in Central Asia. A lot of unprecedented temperature maxima were recorded in the mid-Asian countries at the beginning of the month. The air temperatures in Turkmenistan, Uzbekistan, Tajikistan and Kyrgyzstan often exceeded +30…33°. The monthly-averaged temperatures all over Central Asia were 2-4 or more degrees above the normal values.
In North Africa, these temperatures were above normal almost everywhere: 2-4 or more degrees above all the way from the Atlantic coast to the Red Sea. The monthly-averaged air temperatures matched their normal values just in a number of locations, or were slightly lower in individual northern regions of Algeria and Morocco, for example. The average April temperature in North Africa was the fourth or fifth highest in the ranking list compiled since 1891.
In Europe, April started with cold weather and new daily minima of air temperatures in Germany, France and the Netherlands. Temperatures below -6° were recorded in Germany, and below -2° in France and the Netherlands. No such colds have been observed in London over the last seventy years in April. Cold weather propagated as far as the south of the continent where such colds have not been seen for more than 55 years in Spain and Italy. The record-breaking temperatures at night were measured in Greece, North Macedonia, Romania, Italy and Poland. There, the temperature sometimes dropped down to -3…-4° in certain places. The weather was abnormally warm in the north of the Scandinavian countries only, accompanied with new daily temperature maxima. As a result, the air temperature averaged over the entire Europe was close to normal. This result was basically achieved against a positive background of anomalies in the western part of the continent and against a negative background in the eastern part.
Cold weather prevailed in most of Canada and of the US this April. The monthly-averaged temperature anomalies were measured at -2…-4°. In Canada, the monthly-averaged temperatures were higher than normal along the Atlantic coast and in the polar area only, and in the USA, in Alaska and in the southern states. The weather in Mexico was very hot: the observed temperature anomalies were +2…4° and more.
In the Arctic, the monthly-averaged air temperature was more than 2° above the normal value. The largest anomalies (exceeding 2-4°) took place in the north of Asia and North America. The temperatures were normal in the north of Europe, and less than normal in the north-east of Greenland.
Within an accuracy of 0.1°С, the average air temperature in April in the Northern Hemisphere can be put on the fourth to seventh line in the list of highest values since 1891.
In Moscow, the average temperature in April was +5.8°, exactly matching the normal value.
Sea Surface Temperature
La Niña, the cold episode of the Southern Oscillation, persisted in the Pacific Ocean for the ninth month in succession. Negative SST anomalies were observed at latitudes from zero to 10°N and longitudes from 160°E to those of the coasts of South and Central America in the Northern Hemisphere, and along the coast of South America as well as in the central part of the Ocean to 10-15°S in the Southern Hemisphere. Thus, the area occupied by such anomalies has not yet decreased in comparison to the previous months.
High positive SST anomalies (in excess of +1…2°) in the Northern Hemisphere were measured at the subtropical latitudes of the Pacific Ocean, while negative ones, in the South China Sea, along the coasts of the US, Canada and Alaska, and in the Bering Strait. The average SST anomaly of the Pacific Ocean in the Northern Hemisphere was 0.1° less than its record-breaking value in April 1989 despite the presence of major Niña this month.
In the Atlantic Ocean, even so most of its surface in the Northern Hemisphere was occupied by positive anomalies, only those of them located east of the US coast as well as in the Baltic and North Seas may be considered large (more than 1°). The temperature in the rest of the Atlantic Ocean in the Northern Hemisphere was close to normal. Weak positive anomalies were observed in most of the Ocean, and weak negative ones, along the coast of Canada and west of the coast of Africa in the tropical zone, as well as in the central part of the Mediterranean Sea and alongside the interface with the Arctic Ocean water bodies.
A lot of precipitation fell in the ETR in April: its monthly totals were subnormal just in a few constituent entities of the Federation, all of them either in the north (in the Leningrad and Kaliningrad Regions and in the Republics of Karelia and Komi), or in the south (in the Astrakhan Region and in the Republics of Kalmykia, Adygeya, Dagestan, North Ossetia, Chechnya, Ingushetia and Karachay-Cherkessia). In the rest of the territory, the precipitation amounts were much greater than normal, e.g., 2-3 or more times greater in the Central Federal District, 1.5-2.0 or more times greater in the Volga Federal District, and more than 1.5 times the normal amount in the Republic of Crimea.
Unprecedented precipitation early in April was observed in the eastern areas of the Volga region. New daily maxima up to half the normal monthly totals were recorded in Kirov and Izhevsk. In mid-April, rains and snowfalls swept across the central region. Up to 20-30 mm of precipitation in the form of rain, sleet and snow fell in a couple of days in the Moscow, Vladimir, Voronezh, Tula, Kaluga and Bryansk Regions. At the same time, heavy rains and snowfalls hit the Volga region everywhere from Tatarstan to the Lower Volga, bringing up to 25 mm of precipitation in places. A new daily maximum was set in Kazan. At the beginning of the third decade, the record-breaking quantities of atmospheric moisture, up to 20 mm per day, were reported again in the Kursk, Smolensk, Bryansk and Kaluga Regions. The rivers were filled with rainwater to the brim.
The monthly precipitation totals in the Urals were normal. In Siberia, the figures varied from small to large, with normal or above-normal amounts in the Tomsk Region, Altai, Taimyr and Evenkiya, and subnormal ones in the rest of the territory. The rains across the south of the Krasnoyarsk Territory were heaviest ever observed.
In the Far East, the precipitation amounts were subnormal in Trans-Baikal and in the Amur Region only, and normal or larger than that elsewhere: 1.5 times larger in Kamchatka and in certain regions of the Khabarovsk Territory.
In China, the north-eastern province of Heilongjiang received increased or roughly normal precipitation in April. But to the south, the monthly precipitation totals in the east of China and in Mongolia amounted to only half of the normal value or less. A similar situation was observed in the west and south of China. At the end of the month, the central and south-western regions of the country were hit by torrential rains that caused floods. The height of flood waters in the province of Sichuan reached two metres, and many agricultural lands were flooded as a result. The normal precipitation amounts in this area were exceeded by 2-3 times. At the end of April, snow fell in Beijing and its surroundings. In Japan, the precipitation figures were normal, and in Korea, less than that.
Many rains came to the countries of South-East Asia, in quantities exceeding 3-4 times their normal amounts in some places. Heavy rain unusual for this time of year hit Vietnam where 350 mm of rainwater – more than seven times the normal monthly quantity – accumulated in Da Nang in a single day. Water flows on the highways reached half a metre in height, completely immobilizing road traffic.
Almost no rains occurred in India and Pakistan, with the exception of a singular heavy rain along the western coast of India: so heavy that a new maximum of total precipitation for April was recorded in the state of Goa.
No rains fell in the Near and Middle East, and very few of them, in Central Asia.
The weather in North Africa was just as dry this April, excluding the south area along the Gulf of Guinea and the coastal regions of Algeria and Morocco where the monthly precipitation totals were normal or increased.
In Europe, a lot of rains went to the countries located from the Baltic to the Balkans in the east of the continent. There, the normal values were exceeded by 1.5 or more times in places. A similar picture was observed in the west, viz., in Spain where the monthly precipitation totals were even higher, and reached 200-250%. Precipitation in Germany was about normal, but insufficient or altogether scarce in the rest of the continent: for example, less than 50% of the normal amount in the north of Italy, partly in France, in the UK and in the Scandinavian countries. Extraordinary heavy rains fell in Belarus and resulted in new daily maxima of precipitation totals in a number of locations. In France, snowfalls were still observed on the slopes of the Alps.
The eastern and central states of the USA received precipitation in normal amounts, or in increased ones that were especially large in the states bordering Canada (North and South Dakotas, Montana and Minnesota) where the normal figures were exceeded by 2-3 or more times. In the west of the country from California to Kansas and Oklahoma, almost no rains were observed this month. Numerous fires broke out in Arizona and New Mexico due to dry and hot weather. In Canada, the weather was dry in most of the country, with the exception of its polar region and of the areas bordering the US in the states from Saskatchewan to Quebec. A lot of rains came to Mexico, to a number of Caribbean countries and to the northern regions of Columbia.
In Moscow, 72 mm of precipitation fell during this month, amounting to 177% of the normal value. This April was the fifth wettest in the meteorological chronicle of the country since 1891.
Hydrometcentre of Russia