THE MAIN WEATHER AND CLIMATE FEATURES OF THE NORTHERN HEMISPHERE IN MAY 2018

Air Temperature.

During at least two last years (2016 and 2017) every month the average monthly air temperature in the Northern Hemisphere was in the first five highest values on the record, i.e. since 1891. However, the situation has been changed in the beginning of 2018. In January, the average monthly air temperature got 6th rank, and then it reached the end of the second five values, in February – 9th rank, in April – 8th one. May continued this tendency. Its average monthly air temperature holds 7-12 line among the highest ranged values.
Oceans are responsible substantially for the cold anomalies of the last May. In the north of Indian ocean, in the north and south of Atlantic and central part of Pacific oceans the average monthly air temperature became lower the norm, at some places by 2° and lower. In the continents, the cold dominated in a lot of Northern Hemisphere regions.
First of all, it is Canada, in the north-east of which the average monthly air temperature is above the norm by 2-4° and more. But in comparison with the south neighbour – USA- this warmth can be considered as not apparent, because in all US territory in May the warm, sometimes hot weather dominated. In all country territory, the average monthly air temperatures exceeded the norms by 2° and more, in the centre and Pacific coast – by 4-6° and more. In some places, the temperature was higher 35°. Warm air was transferred far to the east to the Atlantic ocean, in subtropical latitudes of it the May average air temperature exceeded the norm by 2-4°. In USA, the last May became the warmest one on the record in the country. The previous record achievement of the average monthly air temperature was exceeded by more than 0.5°. In Mexico, it was very warm, especially in the north of the country.

Another cold centre was in the north-west of Africa. In Morocco, Mauritania, west of Algeria and Senegal the last May became colder than usual, in some places by 1-2°. At the same time, in the east of the continent in Egypt and Sudan the warmth prevailed, as well as in the neighbouring countries of the Middle East. Here the monthly anomalies are +2…4°.
China enjoyed the heat, especially its east and south provinces, and Mongolia. Hot daily maximums were recorded the China, Korea and Japan. However, temporary cold air penetrations took place. So, in the third decade the frosts to -4° turned back to Mongolia, to the mountainous areas – to -7°.
The heat more than 40° was in Pakistan, at the same time in the south of India it was colder than usual.
In Kazakhstan and Central Asia republics the most part of the month the cold air dominated, and in the north of the region May became colder the norm by 2° and lower. However, warmth from time to time penetrated here, the air was heated up to 35-40°. In Chimkent, Samarkand and some other points the new daily air temperature maximums were registered. As a result, in the south of Kazakhstan and Central Asia republics the average monthly air temperature was close to the norm.
Once again, as in March, the record heat was in Europe. The last May here became the warmest one on the record. His average monthly air temperature exceeded the last achievement of 2003 by more than 1°. In the East European and Scandinavian countries, the new maximums were registering. In most territory of the continent the air temperature norm were exceeded by 2° and more, in the north of Germany, in Scandinavia and east of the continent – by 4-5° and more. In Oslo the anomaly is +5.7°, Stockholm, Copenhagen and Brno - +4.4°, Warsaw - +4.7, in Budapest and Belgrade - +4.1°, Tallinn and Kaunas - +4.8°, Vilnius and Minsk - +4.5°.
In Russia, the average monthly air temperature is close to the norm. However, it was achieved by distinct ways. In the European territory, the most part of the month kept the warm weather and the average monthly air temperatures exceeded the norms by 2-4°. Sometimes one can imagine that the summer has already come. From Barents sea to the Black sea the new daily temperature maximums were registered, its values approached to 30°. To be impartial one should note that sometimes to the Central Russia the Arctic air penetrated and temperature dropped down below the zero mark.
In the Upper Volga, Urals and West Siberia the situation is another. Here almost all month it was colder than usual. The frosts were frequent, especially in the last days of the month. In Altai, the new minimum air temperature values were registered. In some days, the frosts reached -8…-12°. As a result, the average monthly air temperature here was below the norm by 2-4°. In Urals, it was the coldest May in XXI century.
In the east of Siberia, the cold of the second decade opposed to the warmth of the first and second decades. In the first case, the average decade anomalies reached +4…+6°, in the second one - -2…-3°. Here, together with temperature higher 30° in some days (Irkutsk region, republic of Buryatia) it was cold to -10° (Transbaikalia).
In the Far East, the situation came close to the record achievements in the south of the region. The last month here became the second warmest since 1891 and succeeds only to May of 2002. In the last days of May, Far East was covered by the warmth. In Kamchatka region, Magadan, Amur, Sakhalin areas the daily temperature maximums were registered.
The spring of 2018 was finished in May. In Russia in general the temperature values one can recognize as close to the norm. Although one can consider the last spring in Volga area, Urals, east of North-West federal district as cold (in some places it is colder than usual by 2° and more), at the same time in other country territory its average monthly air temperature is above the norm (in Transbaikalia, and Far East – by 2-4°). In Volga area, Urals and West Siberia inhabitants did not see such cold spring in the present century.
The spring average air temperature in the Northern Hemisphere, as well as in May, is beyond the first five of the highest values. Noticeably warmer than usual in became in Europe, in the Middle East, Central Asia, China, North Africa, north of Mexico and south-west of USA, in the subtropics of Pacific ocean. It became colder than usual (like in May) in the vast ocean areas and partially in Russia and Canada. In China the last spring is the warmest on the record, in Europe it reached the first five of the warmest ones.
In Moscow the May average monthly air temperature is +16.2°, anomaly is +3.0. This is the 8th warmest May since 1891. The spring also became the abnormally warm, but slightly, by 0.7°. Spring of 2018 in Moscow was frequently sunny. According to Moscow State University data, in every month of the last spring the sunny hours quantity in the city substantially exceeded the norms. As a result, during the spring period the sunny hours quantity reached 744, that is above the norm by 30%. It is the second result of this century. The leader is spring of 2002 – 780 sunny hours.

Ocean Surface Temperature.

In Pacific ocean, the cold phase of the Southern oscillation - La Niña has been finished. Although in the east of equatorial latitudes and particularly in Southern Hemisphere the negative SST anomalies has been observing, but they are smaller than 0.5° everywhere. In the Pacific ocean the average SST anomaly in the Northern Hemisphere was kept at the last months level and has set +0.5°. Noticeably higher the norm (by 1-2° and more) the sea surface temperature to the east of Japan, i.e. in the area of the warm stream Kuroshio, and in the north of Bering sea, and in tropical latitudes in the east of the ocean. Vice versa, in the west of tropical latitudes and central part of the ocean the negative SST anomalies were formed.
In the Atlantic ocean the average SST anomaly has been keeping at the previous level, but on the lower one - +0.2°. Abnormally warm water in subtropics (exceeding by +2…3°) opposes to the abnormally cold one in the tropics and mid latitudes. So, apparently the substantial increasing of the warm climate streams in subtropical of the both west ocean areas – Atlantic and Pacific ones. In both oceans, these areas with large positive SST anomalies correspond well with the same areas of air temperature positive anomalies. Very warm water (anomalies more than 1-2°) was formed in the outlying seas of the Atlantic ocean – Mediterranean, Black, North, Baltic seas and on the margin of the Atlantic and Arctic oceans.

Precipitation.

There were a few precipitations in the European territory of Russia. Their monthly sums reached the norm only in the Central area. The most part of the precipitations has been got in the end of the first and beginning of the second decades. In some places here it was kept the half and up to two thirds of the monthly norms over the several days. The new daily precipitations maximums were registered. South areas had a few precipitations. In the Low Volga area in some places, it was absence of the rains. In Crimea it was officially declared about drought, which has already caused the damage more than 1 billion roubles cost.
In the Urals and east of Volga area, in Siberia it was plenty of precipitations. In some places, they exceeded the norms in 1.5-2.5 times. In Altai the heavy showers over the first decade brought 70-80% of the monthly precipitation norm, in the second one exceeded it in 2 times and more. In this month, the snow here became frequent phenomenon, not only in the beginning, but in the end of the month, for instance, in Irkutsk area, where the “white blanket” reached the depth of 10 cm.
May snowfall took place in Amur area, but in one day, the snow was melted by the rains followed. Yakutia and Magadan district have got up to two precipitations norms and more, in Chukotka, Kamchatka and south areas of Far East, except Primorye, it was a few precipitations.
In the east of Asia in Korea, Japan, China it was norm of precipitations and more. In Korea and provinces of the Central China, they exceeded the norms in 2 times. Heavy showers in Sichuan province forced the authorities to rescue the thousands of people. Mongolia was left almost without rains.
South-East Asia has got a lot of precipitations in this month. In Thailand, Laos, Myanmar have got up to 40-50mm of the rain over the day, up to 1.5-2.5 norms over the month.
Summer monsoon came to the south and south-east of India, Sri Lanka and Bangladesh. In the Indian states of Uttar-Pradesh, Bihar, Jharkhand, Mansur, Kerala and Sri Lanka the monthly norms were exceeded in 2-3 times. The rains caused the floods and casualties.
In the most part of the Central Asia, it was dry weather. Exception was only in the north-east of Kazakhstan, where precipitations have set the norm, in the beginning of the month the snow was falling. In the other territory of the region in some places, it was the absence of precipitations, although singly heavy rains took place. In Tashkent, the heavy rains during half of the day, changed streets of the Uzbekistan capital into rivers. The same situation was here last time in 2010, before this – in 1998, in the same time. The same it was last time in 2010, before it in 1998, in the same time.
Astonishing phenomenon was Middle East. One of the driest in the world, this territory has blossomed, inundated by rains. From Turkey to Pakistan the monthly precipitations sums exceeded the norms at some places in 1.5-2.0 times, in places of tropical cyclones Sagar and Mekunu, there are Yemen, Oman, Saudi Arabia, UAE – in 3-5 times. In coastal areas over the cyclone time presence, it fell to 300mm of the rains, in the mountains – to 800mm. This is more than year’s norm. It was natural for the floods. It was informed on casualties and traffic collapse. Numerous showers inundated Transcaucasia and Anatolia. Turkish meteorologists noted that no one has seen such heavy rains in the capital Ankara. Armenia have not seen such heave showers more than 30 years.
In North Africa the rains covered the Mediterranean coast and in Sahel. Here the precipitations were in the norm, in some places even more in 2-3 times. In other territory, it was dry, except the African Horn area. Heavy showers fell here for several months, were followed by the precipitations, brought by the tropical cyclone Sagar. Heavy floods, portable water pollution have already caused many human losses. Hundreds of thousand people were evacuated, the destiny of others depends on humanitarian help.
In the Eastern Europe and in Scandinavia it was mainly dry weather. Monthly precipitations sums barely have set the half of the norm. In many areas of the north there were only millimetres. In Balkans and Central Europe is the precipitations norm, in the west – more the norm. Heavy rains fell in Portugal, Italy, Albania (up to 20-50mm over the day). In UK in some areas the monthly precipitations norm was fulfilled over the day. The floods emerged.
In USA a lot of precipitations happened in Atlantic coast states from Florida to Virginia. Here their sums were close to the extremums and exceed the norms in 2.5-3.5 times. Further to the west the precipitations amount were decreased to the norm, from Mexico Gulf to California and along the Pacific coast there were a few, in some places – absence.
Catastrophic flood took place in the Canadian province of Britain Columbia. After two days of heavy rains, the floods emerged, which were named the heaviest over the last 70 years. In general, in the most part of the country the precipitations became in the norm and more.
In Moscow the monthly precipitations sum has set 61mm or 120% of the norm.