The main weather and climate features of the northern hemisphere in April 2017

Air Temperature

In the European territory of Russia (ETR) the temperature conditions were substantially different. In the first ten-day period the March abnormally warm weather was kept. In the north-west and centre of ETU the air temperature anomalies over the first decade reached +3…6 and more. Here were the numerous warm records: Kaliningrad, Pskov, Smolensk, Bryansk, etc. But in the second ten days cold penetrated here, and ten-days period temperature anomalies have set -2…-3°. In the third decade the cold reached the south Russian border. Average decade temperature anomalies exceeded -3…-4°. In the west and central ETR regions, in Volga area and in the south (Crimea, Krasnodar, Stavropol districts) the new daily temperature minimums were achieved. In Smolensk district the frosts reached -15°, Tambov - -9°, the light frosts were even in the south – Rostov district, Stavropol district and in Republic of North Ossetia-Alania. The warmth came to the Central Russia only in the last day of the month.

Striking contrast of ETR became the temperature on the east of Urals. If in Urals, particularly its northern part, in the first and second decade the temperature conditions corresponded to the norm, and abnormal warmth came here only in the third decade, but in Siberia and in Far East it dominated all month long. The average decade temperature anomalies reached here +7…8°. In the north of Far East the April 2017 is the warmest on the country record. In Siberia, seven out of ten warmest Aprils occured in XXI century.

“Siberian” warm anomaly penetrated to the north and central areas of China, Mongolia and Korea. The new daily air temperature maximums have set. In Beijing the April anomaly is +4.0°, in Ulan-Bator - +4.9°, Pyongyang - +3.2°. However, in the vast territory of China, especially to the south of Chang Jiang, the average monthly temperature conditions corresponded to the norm, as well as in the most part of Japan.

Rough norm and even less was the air temperature in south-east Asian countries.

In the most part of India, as in March, the air temperature was close to the norm, but in the north of the country and in the neighbouring areas of Pakistan is the abnormally hot weather. Air temperature exceeds 40°. The new temperature records were reached.

In Central Asia air temperature in the south of Kazakhstan exceeded the norm by 1-2°, in the south of the country and in neighbouring areas of Tajikistan and Kyrgyzstan even less the norm.

Noticeably hotter than usual is was in the most part of Middle East. In Jordan and Kuwait the average monthly air temperature anomaly is +2° and more, in Saudi Arabia and Iran - +3° and more. Nevertheless, in the north of the region in Transcaucasia and Turkey the average monthly air temperature corresponds to the norm, and in some places is lower the norm.

Air temperature in North Africa in average over the month approximately is close to the norm or higher. In Algeria, Tunisia, Morocco, Senegal this exceeding is +2° and more.

In Europe, as well as in ETR, at the beginning of the month is was warm “grace”. The air temperature reached +20°, in some days – up to +25°, and in Spain and Portugal – even warmer. In the north of Italy, in French Riviera, Pyrenean peninsula and Central Europe the new temperature records have been set (Venice, Florence, Nice, Madrid, Budapest and others). Everything was changed in the second half of the month, especially in the east of the continent. Rear for this time of the year colds came to Scandinavian and Baltic countries, Belarus and Czech, Ukraine. Air temperature dropped to -5…-8°. From Baltic to Ukraine the air cooled down to the record values. As a result, average monthly air temperature in the most part of the continent corresponds to the norm. Only in south-west of Spain and Portugal it is higher the norm by 2-3°, and in the north-east in Scandinavian and Baltic countries it is lower – at some places by 1°.

In USA the last April became extremely warm for the east part of the country. Everywhere from Canadian border to Florida the average monthly air temperatures substantially exceeded the norms. In the south Atlantic coast states it was the warmest April on the record. To the south of New-York the average monthly air temperature at some places exceeded the norm by 4-5°. Rough temperature norm was observed in Middle West and Rocky Mountains, and along the Pacific ocean coast it is also exceeded the norm, in California and Arizona – by 2-3°. The same anomalies are in the north of Mexico.

In Canada the air temperature in general corresponded to the norm. Slightly higher the norm it was in south of the country along the US border, also in polar areas, and slightly lower it was in the east of Quebec and in Labrador peninsula.

In general for the Northern Hemisphere April 2017 became the second warmest in history, succeeding the first place in the range series of average monthly air temperatures only to April of the last year.

In Moscow the average monthly air temperature +5.3°, anomaly is -0.5°. Temperature background in the capital in the first and second half of the month distinguished sharply. After the abnormally warm first decade the strong cooling came, which lasted up to the end of the month. This April returning of colds is relatively habitual for Moscow, though considers by people in negative way, because being got used to the warm weather, they are turning back if not to winter, but to the early spring.

Precipitation

In ETR only in the south and the west of the central region the precipitations are less than the norm, but in the other territory there were a lot of , and in some places they were extremely large. The monthly norms exceeding in 1.5-2.0 times was the usual phenomenon, and in North-West, Volga Federal Districts it was 2.0-2.5 norms. In the middle of the month the snow came back to ETR. In Volga area and Chernozemye the depth of the new snow cover reached 12-13 cm. Peterhof fountains were covered with snow and water jets, blowing from the snow, were the wonderful sight.

In the Urals and Siberia, except Altay, there were a lot of precipitations. In the most part of this vast territory their monthly sums exceeded the norm in 1.5-2.0 times, in the south of East Siberia and Baikal area – in 2-3 times.

The norm of precipitations and more was in the west areas of Yakutia, Amur region, Jewish Autonomous Republic and south of Khabarovsk region, though the other areas of Far East Federal District have the deficiency of precipitations. Snowfalls in Far East were the frequently phenomena.

In Mongolia and most part of China there were a few of precipitations. Only in south-west in Sichuan province they have set a norm and more. Some heavy rains were in the south provinces of the country: Hunan, Jiangxi, Zhejiang, Fujian. The precipitations norm is in Japan, with the heave shower rains. At some places it was monthly norm in one day.

In south-east Asia it was substantially higher the norm of precipitations. In Myanmar and in the north of Thailand the norms were exceeded in 2-3 times, and in the other territory in was the norm and more.

In India, except the north areas, it was not precipitations. In Kashmir, Punjab and Uttar-Pradesh there were heavy rains, but in mountainous areas – snowfalls. Here the precipitations norms were exceeded in 1.5-2.0 times. Approximately the same picture was in Pakistan, in the south-west of the country - was dry, in the north-east – close to the norm and more.

Although the most part of Middle East in April did not receive any drop of rain, the heavy showers in the north-west of Iran caused the huge floods with human losses. In this area, as well as in the neighbouring Turkey the precipitations monthly sums have set the norm.

In Kazakhstan, except the west territories, it was a lot of precipitation, in the south they exceeded the norm, as well as in neighbouring areas of Tajikistan and Kirgizia. In Uzbekistan it was deficiency of precipitations, as well as in the most part of Turkmenistan. However, in Caspian area of the country they have set the norm and more.

Dry weather dominated in the most part of North Africa. Only in some areas of Mediterranean coast and Guinean gulf the rains took place. In some areas of Algeria, Côte d’Ivoire, Nigeria, Cameroon the monthly precipitations sums reached the norm and even exceeded it.

“Wet” weather in North and East Europe was a sharp contrast with the dry one in South and West. In Balkans, Italy, Germany and the west of it less the half of monthly norm of precipitations dropped. Nevertheless, here in the north of Italy, in Austria and Slovenia the heavy rains took place, which brought up to half and even to ¾ of the monthly norm. But the main feast of rains and snow was in the north and east of the continent. From Norway and Finland to Ukraine and Moldova the precipitations norms were exceeded in 1.5-2.0 times. In Norway there were rains with 20mm in day intensity. In the middle of the month Baltic countries, Poland, Ukraine and Moldova were covered with snow. Once again the snow cover appeared and, as it could be imagined in the warmest March, forever. Such heavy snowfall was in Moldova the last time in 1955. Over the two days it dropped more than 75 mm of precipitations as a rain and wet snow. The depth of the fresh snow was 60 cm. It never happened before, even during winter. Future harvest of peaches and apricots was eliminated, the early fruits – cherries - gardens suffered. Many areas stayed without electricity because of lines breaks. The common country damage from this disaster is assessed in $3.5 million. Snow covered Ukraine form Kharkov till Odessa. In Black sea area the snow cover was restored once again, with the height up to 10cm.

In USA it was the second wettest April in history. Everywhere, except South California and Arizona, the precipitations were higher the norm. In Kansas, Missouri and Oklahoma in the centre of the country, North and South Carolina in the east, Oregon and Washington in the west the monthly precipitations sums exceeded the norm in 2-4 times. Sometimes the rains were changed by the snow. Because of rains and floods in some states the emergency situation was announced. In South California after the record precipitations in the beginning of the year, which stopped the record draught, once again it was less of the precipitations norm.

The same thing one can say on the neighbouring areas of Mexico, where the deficiency of rains was. But in the central part of the country they make the norm and more. Steady showers happened in Columbia. They caused mudflows and floods with hundreds of casualties.

A lack of precipitation occured in the Pacific and Atlantic provinces of Canada, while in some areas in the central part of the country the precipitation amount was above normal.

In Moscow the monthly precipitation amount was 77 mm or 175% of the norm. This is fourth “wettest” April in the capital. It has not been so much precipitation in April in Moscow over the last 30 years.

Ocean Surface Temperature

The sea surface average temperature anomalies (SST) of Atlantic and Pacific oceans in the North Hemisphere in April 2017 remained at the same level, as in the previous month, i.e. 0.5°.

In equatorial latitudes of Pacific ocean the neutral phase of Southern oscillation is being kept. The abnormally warm water is observing in the tropical latitudes of the central part of the ocean, and abnormally cold – along all strip of middle latitudes.

In Atlantic ocean the abnormally warm water is observing in Mexico gulf, in Gulfstream sources, as well as in west part of Mediterranean sea, and abnormally cold water is near the coast of North America, in Dutch strait between Greenland and Iceland.

As before, the surface temperature of the Barents sea is noticeably above the norm.