MAIN WEATHER AND CLIMATE TRAITS IN THE NORTHEN HEMISPHERE AS OF MAY 2019

Air Temperature

In the west of Russia, the anomalously cold weather that settled there in the end of April preserved in the beginning of May. Cold air from European countries was still flowing to Russia. Sub-normal temperatures recorded in the Leningrad, Pskov and Novgorod Regions culminated in night frosts and record-breaking temperature minima in the Kaliningrad Region. The frosts and unprecedented colds in the first decade were also observed in Central Russia, the Upper Volga Region and the Urals. Of all the ETR, the abnormal warmth at that time was only in the south of Russia (the Krasnodar and Sevastopol Territories) and in the Middle and Lower Volga Regions: there, the thermometer readings could reach as high as +30°.
In contrast to this, the weather was very warm in the east of the country. New air temperature maxima were repeatedly recorded all the way from the Urals to Chukotka and Primorye. Sometimes, the air heated to +20° in Yakutia and almost to +30° in the south of the Urals and of the Far East. The normal values of decade-averaged air temperatures in the Urals and in the north of the Far East were exceeded by 5-7°.
Further on, such abnormal high-temperature background started to fade throughout the country, and the anomalies normally decayed to at most +2…4° in the second and third decades. Spots of anomalous heat creating new temperature maxima still survived in the Volga and Cis-Ural Regions in the second decade, but the bitter arctic cold rushing down to the ETR and Siberia in the third decade brought frosts and even record-breaking colds to Central Russia, to the west of the ETR and to the south of Siberia. In the second decade, the air temperature anomalies in the south areas of the Krasnoyarsk Territory, in Khakassia and Tyva were -2…-5°.

In the last decade of May, the air temperature was approximately normal in most parts of the country except for the ETR and the Russian North from Taimyr to Kolyma where the weather was to a certain degree warmer than usual. At the end of the month, the records of cold were beaten in Chukotka, and frosts visited Central Russia, the Volga Region, the Urals and South Siberia from time to time.
In terms of the overall monthly figures, the air temperature was above normal almost everywhere in the country. The weather was somewhat cooler than usual only in the southern parts of the Krasnoyarsk territory, and partially in the Altai and Tyva Republics. The normal values of monthly-averaged air temperatures in the ETR and the Urals, in the Taimyr and Evenki Autonomous Districts, in the Primorye and in the north of the Far East were exceeded by 2° or more. This May is ranked the seventh to ninth warmest one in the whole history of regular meteorological observations in the country.
The average temperature in spring 2019 is at the fourth place after 2017, 2014 and 1990 in the ranking list of highest values ever recorded in Russia. The season-averaged air temperature exceeded its normal value by 2° or more almost throughout the entire territory of the Russian Federation, and by 2° or more in the Yamalo-Nenets, Taimyr and Evenki Autonomous Districts as well as in the north of Yakutia and of the Far East. In most Federal Districts excluding the North-West and North-Caucasus ones, the past spring is in the top ten of warmest ones in the metrological chronicles of the regions.
In most of China, the monthly-averaged air temperatures in May matched the normal values, with the exception of north-eastern and coastal eastern provinces where the heat could reach as high as +40°. The same temperature extremes above the ever observed maxima were recorded in Korea and Japan. Thousands of persons in China were hospitalised after heat shocks, and lethal accidents were reported. The monthly-averaged air temperature was 2-3° above the normal value.
In South-East Asia, the weather was hotter than usual. There, the air temperature anomalies amounted to +1.5-3.0°.
In India, the weather remained very hot for the second month already. The thermometer readings were +45-47° in the north and up to +40° in the south of the country. In its central regions and in the south of Pakistan, the monthly-averaged air temperature exceeded the normal value by about 2°.
In most parts of Kazakhstan and Middle Asia, the intense heat prevailed, and the centenary temperature maxima were exceeded. Yet the northern and eastern territories were sometimes blown over by cold air, and the temperatures dropped down below zero. For this reason, the monthly-averaged air temperature was slightly below the normal value in the north and east of Kazakhstan but noticeably above it in the rest of Central Asia. In the south of Kazakhstan, in Uzbekistan and Turkmenistan, the normal value was exceeded by 2-3°.
The Near East was suffering from heat. The air heated to +43° in the central regions of Israel and Jordan, and to +34° on the Mediterranean coast, resulting in fires. The weather was also excessively hot in Transcaucasia where the temperatures rose up to +35°. In the Levant and Transcaucasian countries, the normal monthly-averaged air temperatures were exceeded by 2° or more in some places.
Extremely hot air flowed to the Near East from Africa where the temperatures settled at above +45° in Egypt. In the north-west of the continent, it was very hot too: the air temperatures were 2° or more above their normal values in Morocco, Algeria and Egypt. At the same time, occasional outbreaks of cold air from Europe made the weather in the north of Algeria and Libya cooler than usual on the monthly average.
The monthly-averaged air temperature in Europe returned to its normal value after more than a year since April 2018 when it started to exceed this value, quite significantly sometimes. This was because Central and Northern Europe had been besieged by cold air for a considerable part of the month. On a monthly average, sub-normal temperature conditions were formed in all areas from Scandinavia to Italy and Balkans and, as we saw earlier, to the African coast. The monthly-averaged anomalies were -2° or more in certain places in Germany, Austria, Czechia and the Balkan countries. On the other hand, the weather was much warmer than usual in the west, i.e., in Portugal and Spain, and in the east, i.e., in Belarus, Ukraine and Moldova: by 2-3° here and there. New temperature maxima were reported in Portugal including its capital Lisbon. The same also occurred in the east of the continent where the hot air from Africa penetrated. In Cyprus, a new temperature maximum of +41.9° was recorded for May.
Cold air hit most of the USA. In the central and northern regions of the country, the anomalies of monthly-averaged temperature were -2…-4° in some places. The weather was warmer than usual nowhere else than in the east, especially the south-east, and on the west along the Pacific coast: again, by 2-4° in some places. In the south-east (the states of Florida, Georgia, Alabama, North and South Carolina), this May was the second warmest one in the history of the USA. It was very warm in Alaska where this month was the third warmest May in the history of meteorological observations. In Canada, the weather in May was also warmer than usual, especially in the north of the country where the monthly-averaged temperatures exceeded the normal values by 2-4° or more.
In the north of the American continent and in most northern territories of Eurasia, the weather was so hot as to promote this May in the Arctic to the fourth position of warmest ones in the history. The air temperature averaged over the entire Arctic territory was 2.5° above the normal value. High temperatures resulted in early melting of glaciers. According to NASA, the glaciers in Greenland have been melting at an increased rate for the past twenty years.
The rate of global warming is known to slow down in 2018 to a certain degree. Among everything else, this is supported by the fact that the average air temperature in neither season of that year has entered the top three of highest ones in the history of meteorological observations. The latter trend did not change in winter 2018/2019, but disappeared this spring when the average temperature in the Northern Hemisphere became the second highest for the whole history of meteorological observations on the planet, i.e., since 1891. Only the spring 2016 was warmer.
This time, the season-averaged air temperature across the continents exceeded the normal value everywhere excluding a part of the US territory. This is most evident in middle and high latitudes where the last spring was warmer than usual by 2-4° or more, or in Alaska and in parts of the polar Canadian regions where it was warmer by 6° or more. In the Arctic, this spring was the warmest one in the meteorological chronicle of the region.
The average air temperature in spring 2019 was less than normal solely in parts of the Atlantic and Pacific oceans in middle and tropical latitudes, and partially in the USA where the anomalies of season-averaged temperature reached -2° in certain northern regions of the country.
In Moscow, the average air temperature in May was 16.3° and the anomaly was +3.2°. It was the eighth warmest May in the history of the capital. The spring was also very warm, to be exact, the fifth warmest in the meteorological chronicle; however, its average temperature was much lower (by more than 0.5°) than the one during the record-breaking spring of 1975.
Ocean surface temperature

In the Pacific Ocean, the average SST anomaly in the Northern Hemisphere increased by 0.1° and thus exceeded +0.5°. A weak El Nino survived in eastern equatorial latitudes of the Pacific. The average SST anomaly in the El Nino recording area (120-170°W and 5°N-5°S) was less than +1°. The model calculations indicate that the temperature conditions in the El Nino zone will remain the same in the nearest months; hence, no further development of the El Nino is anticipated. The SST was much higher than its normal value along the coasts of Canada and Alaska (with the anomalies of up to +2° or above), in eastern tropical latitudes, in the Yellow Sea and Sea of Japan, and along the coast of Japan. Anomalously cold water was observed in some areas of middle latitudes and in the Sea of Okhotsk.
In the Atlantic Ocean, the average SST anomaly did not change as compared to the previous month. In low latitudes and to the east of Newfoundland, the SST was below normal, by 1° or more in some places. Water was very warm off the US coast in the Gulf Stream sources (with the anomalies of up to +2° or above). The SST exceeded the normal value in the Barents Sea, whereas negative SST anomalies were observed along the Northern Sea Route. The cold weather in Europe has affected the water temperature in the Mediterranean. The temperature was about 16-18° on the monthly average (which is less than usual in May) and reached +20° off the coast of the Levant only.

Precipitation

Whereas April was dry in the ETR, the precipitation totals in May reached their normal values almost everywhere or exceeded them in many constituent territories of the Federation: e.g., nearly by two times in the west (the Leningrad, Novgorod and Pskov Regions, and the Republic of Karelia) or in the centre of the country (the Oryol, Bryansk and Kursk Regions). A moderate lack of precipitation was only evident in the Crimea and in some republics of the North Caucasus. In the first decade, heavy rains fell in Central Russia. Up to 18 mm of atmospheric moisture were recorded daily, and the normal amounts of monthly precipitation in some regions were achieved by the middle of the month already. In the north of the ETR (the Kola Peninsula and Karelia), snow was still falling at the beginning of May.
Snows were more frequent to the east of the Urals. They were observed in the south of West Siberia where a temporary snow cover was recreated, in Trans-Baikal, on the Kolyma and in the arctic region. The precipitation amounts were close to normal in the Urals and in most of Siberia with the exception of its south (the Novosibirsk and Kemerovo Regions, the Altai Territory as well as the Altai, Khakassia and Tyva Republics) where the monthly precipitation totals hardly surpassed a half of their normal values. The same was observed in the Irkutsk Region. A lot of precipitation went to the Far East. In the Magadan, Khabarovsk and Primorye Territories and in the Jewish Autonomous Region, the normal monthly figures were exceeded by two or more times. In the third decade, a huge amount of precipitation descended upon the Primorye and Khabarovsk Territories, the Amur Region and the Southern Kuril Islands. There, the daily precipitation amounts in certain places exceeded the amounts normally observed for a month or even for a month and a half. Up to 50-70 mm of rain accumulated per 12 hours. The water level in rivers rose by half a metre or more. This resulted in floods.
Plenty of precipitation went to China. In the central and northern provinces and in some places in the south, the normal monthly amounts were exceeded by two times or more. Showers caused floods that required urgent evacuation of people, damaged agricultural lands, destroyed houses, bridges and roads, and lead to fatal casualties. Korea and Japan were also flooded by rains. Up to 50 mm of rainwater per day were recorded in the south of the Korean Peninsula.
In India, the monsoon did not set in yet and the precipitation was scarce, while in neighbouring Pakistan, the precipitation was in abundance: 1.5 times the normal value in places.
The weather was dry in most of Central Asia. Fair amounts of rains fell in the east of Kazakhstan only; at the same time, heavy showers poured down on Afghanistan again.
It was mostly dry in the Near and Middle East. Yet, heavy showers fell in individual regions of the UAE, Saudi Arabia and Transcaucasia, causing floods in the east of Georgia.
On the African continent, many rains came to Algeria and Tunisia where the daily amounts of rainwater measured at 60-80 mm.
In Europe, May was rich in rains. Aside from the very west of the continent (Portugal, Spain and France), the monthly precipitation amounts met their normal figures or significantly exceeded them in many regions. In Italy, in the Balkan countries, in Ukraine, Romania and Moldova, Germany and Austria, Sweden and Finland, the normal precipitation amounts were exceeded by two or three times in some places. In the south-east of the continent, rains were accompanied by hails and posed a threat as to the harvest of fruit trees. In Bosnia and north-eastern Italy, showers resulted in floods.
Rains flooded the USA. According to NOAA, this May was the second wettest in the history of the country. From the Pacific to the Atlantic save for the south-west states (Florida, Georgia and South Carolina), the monthly totals exceeded the normal values by two or three times, with the major quantities attributed to the first half of the month. The Mississippi flood was the most severe one after the Great Flood of 1927. The city of Houston in Texas looked like Venice as the streets turned into channels with the cars floating along them. Canada and Mexico, the northern and eastern neighbours of the USA, received little precipitation: as a rule, less than a half of the normal amount.
In Moscow, 57 mm of rain fell in May, which is close to normal. However, the sum of the two nearly normal amounts in March and in May could not compensate for a severe lack of precipitation in April. Due to this, the spring in the capital was not wet enough, with the precipitation totals for a period from March to May amounting to about 80%.