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

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

Air Temperature.

Abnormally cold weather, being dominated in August in Urals and West Siberia, became colder in the Autumn beginning. The territory, captured by colds, increased in the East Siberia and west areas of Yakutia, as well as in High and Middle Volga areas, east areas of Russian North and centre of Russia. It was news from these territories about frosts and new records of the air temperature minimums. In the third decade the temperature anomalies in the south of Urals and the West Siberia, as well as in the west of Yakutia reached -4…-5°. In Urals in XXI century only one September was colder than present one. It happened in 2014. In Siberia the cold September became the phenomena, which one can barely consider as the seldom event. In the recent decade the average monthly air temperature in September has been below the norm the third time. Such cold weather in the last September resulted in decreasing of the temperature below the norm in the area from Arkhangelsk region and the High Volga to Yakutia by 2° and more.
In the other part of European Territory of Russia (ETR) the temperature in the first decade wes close to the norm, but then the warmth began to increase, especially in the second part of the month in the south of ETR. In Crimea, Rostov and Volgograd regions, Krasnodar and Stavropol districts, in the North Caucasus the average daily air temperature many times reached the record values. In this area the average monthly air temperature anomalies exceeded +2…+3°.
In the most part of the Far East, particularly in the north areas, it was warmer than usual. The average monthly air temperature exceeded the norm by 2-3°. In Chukotka the records of maximum temperature have been registered, whereas in Sakhalin and in the south of the region temperature reached the record minimums in the beginning of the month.
In general, in Russia this September was close to the norm by temperature conditions, this is striking distinguishes it from September of the last year, which appeared to be the warmest in the country on the record, i.e. since 1891.

The heat in China did not stop with the finishing of the calendar summer. The first month of the autumn became very warm. In the vast territory the average monthly air temperature anomalies have set +2-4°. In Beijing the air was heated by 3.5° higher the norm. The last September became the second warmest on the record. The warmest one was in 2005.
In the most part of the South and South-East Asia the temperature conditions were approximately close to the norm.
The vast seat of the warmth enveloped all the West Asia. On its periphery the abnormal warmth came to the south of Russia, Central Asia and Kazakhstan. Hot air, arrived here from Arabia and Iran, came here heated up to record high temperatures, being glowed to +40° and more. In all areas of the Middle East, Caucasus, Central Asia and Kazakhstan the average monthly air temperatures are below the norm by 2-4°. (In Ashgabat the anomaly is +3.3°, Dushanbe -+2.4°, Caspian sea coast in Fort Shevchenko - +3.4°, Tbilisi - +3.9°, Amman (Jordan capital) - +2.2°, Bagdad - +3.7°, Tabriz - +3.5°).
North Africa has got a hot September. The average monthly air temperature repeated the record achievement of 2002. In Algeria, Morocco, Egypt its anomaly exceeded +2°, in the sizeable part of the continent - +1°.
European continent was divided to relatively cold central and west parts, and warm east one. So, in Ukraine the average monthly air temperature anomalies in some places exceeded +2…3°, whereas in the west of France and north of Spain they were the same by value, but with opposite sign. As a result, the average monthly air temperature in the continent became close to the norm.
Canada has got the relatively hot September, in the east, central and north provinces the temperature norms were exceeded by 2-4°. Also, one can consider as warm month in USA, where California once again surprised with the record temperature maximums. In this state not only daily, but monthly records have been set. At the same time in the north-east of the country the air was cooled to the record low values.
Arctic for several months has the average air temperatures which are far from record values. (However, in some points the daily maximums were registered, there were in Svalbard and Chukotka). But the warmth, cumulated earlier, apparently is so big that it continues to impact the sea ice distribution. As it known, in September the Arctic ice area reached the annual minimum. In the last September it became closer to the record-small values, than to the record-big ones, exceeded the average value by 1.6 million sq. km over the last 20 years.
The average September temperature of 2017 in the Northern Hemisphere has the third rank among the highest values on the record, i.e. since 1891. The warmer September was only in 2015 and 2016.
In Moscow the average monthly air temperature of September was +13.0°, it is higher the norm by 1.9°. The month was marked with the several periods of the “Indian summer”, when the day air temperature exceeded +20°.

Ocean Surface Temperature.

Sea surface average monthly temperature anomalies of the Atlantic and Pacific oceans in the Northern Hemisphere are kept for a long time at the level of +0.5°. In the equatorial latitudes of the Pacific ocean the area of negative anomalies further increased, and absolute values increased too. The neutral phase of Southern oscillation is being kept and there are no preconditions yet to the new El-Niño initiation. Noticeable part of the ocean is occupied with the positive anomalies. They are particularly large along the north-east Asian coast (Okhotsk and Bering seas) and in the central part of the ocean. But negative anomalies also exist there. In some places, for instance near Japan, one can describe them as big (more than +1°).
In the Atlantic ocean the positive anomalies are situated in the west part of the ocean, and negative ones – in the central part and African coast.
Very warm water is kept in Arctic basin, in some places the anomalies exceed +2°.


Noticeable part of the Russian Federation territory has got in September more than norm of precipitations. In Siberia, except the Arctic territories, the monthly precipitations norms in some areas have set 2-3 norms and more. They are: Evenki area, south of Krasnoyarsk district, Transbaikalia. In the north they saw from time to time the snow squalls with snowstorms.
The Far East has got a lot of precipitations. They exceeded the norms in 2-3 times in the south-east of Yakutia, north of Khabarovsk district, Chukotka, Kurile Islands. In Yakutia the precipitations sums exceeded the monthly norms by the results of the first decade. In the end of September the heavy showers inundated Kurile islands, Sakhalin and north areas of Khabarovsk district. At the same time, Primorye had less than the norm of precipitations.
In the European territory and Urals the heavy rains and at times snowfalls captured the north part of this region. In Ufa the double monthly precipitations norms fell over the 2-3 hours. The monthly precipitations sums from Karelia to Urals exceeded the norms in 1.5-2.5 times. And here it was dry along the Arctic coast. To the south of ETR it was few precipitations. In the Central Federal District they have set approximately the norm and less, in South District – below the norm, at some places in the North Caucasus it was absence of precipitations.
In China in September the hundreds of thousands of people suffered from heavy showers. In the provinces of Guizhou, Hunan, Hubei, Sichuan they caused the landslides, facilities damages and losses of the harvest. According to the local authorities assessment the damage costs the tens of million dollars. The precipitations substantially exceeded the norms in most territory of the country. Only in the north along the Mongolian border, as in Mongolia itself and in the west (Xinjiang) it was few precipitations.
In the South-East Asia the monsoon showers continued to fall. Situation was aggravated by the typhoon Doksuri, which inundated Thailand. In some places it was 100mm of daily rain, which caused the landslides. However, such heavy showers were seldom and atmospheric monthly precipitations sums in this region have roughly set the norm and slightly more.
In India and neighbouring countries – Nepal, Bangladesh, Myanmar, Pakistan – summer monsoon is still active. Heavy rains were everywhere, tens of million people suffered from it. In some places the precipitations norms were exceeded in 2-3 times.
In Central Asia the heavy rains fell in Pamir mountains and in the west of Turkmenistan. Here they exceeded the norm in 1.5-2.5 times. In the east of Kazakhstan it was the precipitations norm, with dry weather in the other territory.
Dry weather dominated in the majority of the Middle East countries. The rains fell only in the south of Arabian Peninsula.
In the North Africa the sub-Sahara countries and some Algerian oases have got substantial quantity of precipitations, in the other subcontinent territory it was dry.
Active cyclones, crossing Europe, caused a lot of rains. Their trajectories often went in the north of the continent. Therefore, a lot of atmospheric precipitations were in north areas of Germany, France, Benelux and east of Europe (Poland, Baltic countries, the West Ukraine). Here the precipitations norms were exceeded in 1.5-2.5 times. Sparse cyclones came from the south, but the precipitations intensity was higher. So, in Vienne the monthly precipitations norms fell over the day, in Italy in Toscana province the shower caused the flood with damage and human losses.
In the North America it was a lot of rains. In USA along the direction from Arizona to Minnesota the monthly precipitations sums exceeded the norm in 1.5-2.5 times. South-east of the country has got the precipitations norm. Dry weather dominated from Gulf of Mexico to the Great Lakes, also in the north-west of the country and, as usual, in the south of California.
Abovementioned rain direction headed further to Canadian territory, crossing provinces of Ontario and Manitoba. Here the precipitations sums, as in the way beginning, exceeded the norms in 1.5-2.5 times. A lot of rains ware also in the north territories and west of the country, whereas in the east the dry weather took place.
Heavy rains fell in the Central America. In Honduras the caused floods and landslides.
In Moscow it was 38 mm of rain, which is 58% of the norm.

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