MAIN WEATHER AND CLIMATE TRAITS IN THE NORTHEN HEMISPHERE AS OF MAY 2020
Air Temperature
The abnormally cold weather which settled in the ETR in April remained cold in May. In addition, negative temperature anomalies were increasing and expanding over time. Whereas in the first decade they were observed in the south only, and the conditions in the rest of the ETR were close to normal, in the second and third decades they reached -2…-3° almost all over the ETR. Frosts in the second half of May were frequent in the North-West, Central and Volga Regions of Russia. The unprecedented minima of air temperature were recorded in many locations of this territory as well as on the Low Volga and the coast of the Sea of Azov. From time to time, warm air broke through to the south of the ETR and then, new events of record-breaking heat were identified in the North Caucasus. In Sochi, the temperature maxima exceeded +30°. On the monthly average, the air temperature everywhere from Karelia to the North Caucasus was about 1.0-1.5° below the normal value.
Just as in April, heat prevailed in the Urals and to the east of them. In the Ural and Siberian Federal Districts, this May was the warmest one in the history of meteorological observations, i.e. since 1891. In this area, the anomalies of monthly-averaged air temperature exceeded +4…+10°, reaching +12° or more in the second decade. The air temperature was over +30° in the Krasnoyarsk Territory and over +25° in Igarka and Taimyr. Due to such hot weather, the ice area in the Kara Sea shrank to its minimum for this time of year.
As for the Far Eastern Federal District, this May was noticeably warmer in Yakutia, Trans-Baikal, the north of the Magadan Region and the Chukotka Autonomous District (the anomalies of +2…+4°). In general, the temperature background in the remaining territories matched the normal ratings for May or slightly exceeded them. Nevertheless, daily temperature maxima were recorded even there, namely, in the Amur and Sakhalin Regions and in the Primorye Territory. Just as in April, the Asian heat overpowered the European cold again. This May was the warmest one in the meteorological chronicle of both the Asian territory of Russia, and Russia as a whole.
As it happened, this spring was abnormally warm in the entire territory of the country: in no location was the season-averaged temperature below its normal value. In the ETR, this temperature was approximately normal due to superposition of the extremely warm weather in March and colder temperatures in the other months of spring. The spring was noticeably warmer than normal everywhere from the Urals to the Far East. The season-averaged temperature of this spring exceeded the normal value by 6-10° in the Urals and in Siberia. Spring 2020 was the warmest spring in the history of meteorological observations in the whole Russia, in its Asian territory, and in a number of its regions (notably, the Ural and Siberian Federal Districts). In the Far East and in the Volga Region, this May entered the Top Five of the warmest ones. Until now, the record-breaking temperature was recorded in 2017, and this May raised the plank by as high as 1.0°.
The weather in May was basically dry in East Asia (China, Mongolia, Korea and Japan). It was most apparent in the northern, north-western and southern provinces of China where the anomalies of monthly-averaged temperature exceeded +2° in some places. New daily maxima were set in the provinces of Henan, Hubei and Zhejiang, as well as in Shanghai. Regarding the whole country, this May was the fifth warmest in the history of meteorological observations. In the rest of East Asia, the temperature distribution was close to normal albeit that with certain emphasis on positive anomalies.
In the countries of South-East Asia, the monthly-averaged air temperature was above the normal value (with the anomalies in the range of +2…+4°).
In anticipation of the summer monsoon, all India suffered from heat above 30°, reaching as high as +43.6° in the north. Truly speaking, it should be noted that the temperature at the same time a year ago was +47°. Still, the distribution of monthly-averaged temperature was close to normal both in this country and in neighbouring Pakistan alike. In the east of India, the weather was slightly colder than usual.
In the Near and Middle East, the monthly-averaged air temperature was well above its normal value, by 2° or more in some areas. In Israel, thermometer readings rose above +40° which was the cause of heat strokes; even fatalities were reported. In Turkey, the absolute maximum temperature in May was surpassed to become +44.5° from now on.
The weather was very hot in Central Asia, with the normal values exceeded by 2-4° or more. In Kazakhstan and Uzbekistan, the temperature reached +40° and above, and in the deserts of Turkmenistan, +43° and above.
Western and Eastern Europe became adversaries. An enormous heat source was formed in the west (Spain, Portugal and France) where the anomalies topped +2…+5°. This May became the warmest ever recorded in Spain and the fifth warmest in the history of France. New absolute maxima of temperature in May were set in Italy and Greece, and new daily maxima, in Madrid, London, Amsterdam, Grenoble and Geneva. In Northern Macedonia, Albania, Greece and Cyprus, thermometer readings rose to +35° and above. On the other hand, cold air soared above Eastern Europe including the ETR. In Poland, Romania, Belarus, in the Baltic countries, in Scandinavia and in Ukraine, the monthly-averaged air temperature was 1-2 or more degrees below the normal value. The record-breaking colds were reported in Belarus and Ukraine. Frosts were observed in the Baltic countries. The temperature in the mountains of Czechia sometimes dropped as low as -10°.
Abnormally warm weather in the east of the European continent occupied North Africa as well: the monthly-averaged air temperatures were 1-2° below the normal value in many countries, and 2-4 or more degrees below it in the Mediterranean area (Algeria, Tunisia and Morocco). This month was the second or third warmest May in the history of meteorological observations, colder than in May 2017 only – solely in terms of the monthly-averages.
In New-Mexico, Arizona, California, Colorado and Utah in the western USA, the monthly-averaged temperature conditions closely matched the maximum values. The anomalies in these states were +2…+5° or higher. If slightly (negative anomalies not exceeding 1°), this month was colder than usual. However, these anomalies were -2° or larger in the east of the country. A similar picture was observed in most of Canada: heat in the west (anomalies up to +2°), and chillness in the remaining territories excluding the polar regions where the monthly-averaged air temperature was 2-3° above the normal value. The anomalies were even higher in Alaska (+3…+5° or greater). Given such temperature distribution, this state entered the Top Five of the warmest Mays in history.
Due to extremely high air temperatures both in the west and in the east of the polar region, the monthly-averaged temperature in the Arctic reproduced the record-breaking value previously set in May 2010.
In overall, this May in the Northern Hemisphere earned the title of the warmest in history. Its average temperature exceeded the previous maximum recorded in 2016.
Spring 2020 was just a step behind still invincible spring 2016, and became the second one in the ranking list of the warmest ones. Large anomalies of up to +4…+8° or higher were observed in the east of Russia, and those in excess of +2°, in Western Europe, North Africa, Central Asia and the Middle East, in the south-west of the USA, in Mexico and Greenland, and all over the Arctic region.
Apart from Russia, this spring was the warmest one in Africa and the fifth warmest in China; its average temperature was above-normal in most of the Hemisphere. Yet, it was below the normal value in a number of territories including Canada, the east of India and individual water bodies of the Atlantic and Pacific Oceans.
In Moscow, the average temperature in May was +11.7°, and the anomaly was -1.4°. The air temperature in the capital was subnormal for the second month in succession. Last time the same was observed in 2004.
Ocean Surface Temperature
The SST anomalies in the Atlantic and Pacific Oceans remained the same as in April.
In the Pacific Ocean, abnormally cold water was observed in the Sea of Okhotsk, to the east of Japan, and in the Bering Straight. The anomalies on the remaining surface of the Ocean were positive, with the largest of them (+1…2° or more) formed at mid-latitudes in the east. The phase of the Southern Oscillation was still neutral.
As for the Atlantic Ocean, cold water – traditionally already – accumulated at subtropical and middle latitudes to the east of the North American coast; and this time, also in the Norwegian and Greenland Seas. During this month, warm water was observed in the Mediterranean, off the coast of Africa in part, in the Gulf of Mexico and along the south-east coast of the US. The latter two areas are most important since tropical hurricanes are developed exactly there after they are conceived in abnormally cold water in the west of the tropical zone.
Precipitation
Such quantity of precipitation that came down to Russia in May has not been seen for a long time. The monthly precipitation totals in almost any constituent entity of the ETR either far exceeded their normal values, or were equal to them otherwise. The latter areas included three in the North-West Federal District (Republic of Karelia, Pskov Region and Nenets Autonomous District), two in the Volga Federal District (Republic of Bashkortostan and Samara Region) and one in each of the South Federal District (Republic of Crimea) and Northern Caucasus Federal District (Karachay-Cherkessia Republic). In the rest of the territory, the normal precipitation amounts were exceeded by 1.5-3.5 times or more. Heavy rains flooded the central and southern regions of Russia bringing from 40 to 80 mm of rainwater per day, which amounted to 70% of the normal monthly value in individual cases. It was still snowing in the north of the ETR. In spite of the rains, soil droughts persisted in the South Federal District and in the south of the Central one. Crops had to be resowed in the Stavropol Territory.
The precipitation quantities were above-normal in the Urals except for the Chelyabinsk Region. All around the vast Siberian territory, a rich variety in the distribution of monthly precipitation totals was observed. In Novosibirsk, Tomsk, Kemerovo and Irkutsk Regions, in the south of the Krasnoyarsk Territory and on Taimyr, these totals were less than the normal values, and in Altai or Khakassia, significantly less, – almost by two times.
The precipitation amounts in the Far East excluding Chukotka were normal or above-normal. The Khabarovsk Territory, Sakhalin and Kamchatka were still covered with snow, and the precipitation rate was very high sometimes. For example, more than 30 mm of precipitation in the form of rain, snow and wet snow accumulated daily in Kamchatka at the beginning of the month, and up to 35 mm of precipitation was brought by the heavy rain on the last day of the month to the Amur River Region and to the south of the Khabarovsk Territory.
The precipitation amounts in China excluding the province of Yunnan where normal or above-normal. The above-normal amounts were mostly observed in the north-east of the country where as much as 1.5 or more times their normal precipitation quantity was accumulated in some places. In the Korean Peninsula, the precipitation was basically normal, but its amounts in the north were large than in the south. In Japan, the precipitation was scarce.
The weather was dry in South-East Asia. Heavy rains in May were observed in Indonesia only and led to floods and mudflows. In some places, the height of flood water reached 2.5 m. Thousands of houses were under water.
Heavy showers came to the north and east of India, to Pakistan and to Bangladesh. Landslides and floods were observed, and damages to hundreds of thousands of hectares of agricultural crops were reported. Snow fell in the mountainous regions of Pakistan. The last time when a snowfall in May was observed was exactly 100 years ago.
In the Near and Middle East, the weather was mostly dry. Heavy rain in Oman brought more than 260 mm of rainwater in two days. Waterfalls occurred in mountains, and floods, in low lands. Water flooded the streets and buildings in the city of Salalah. The precipitation amounts were normal or above-normal in Syria, Lebanon and Turkey. Almost no rains were observed in Transcaucasia.
Heavy showers swept across all East Africa, leading to huge flooding and to a large number of human casualties. More than a million people suffered from the disaster. The largest precipitation amounts over the past forty years were recorded at local meteorological stations. Rains also caused floods in Algeria and in Côte d'Ivoire in the south. In the countries of the Gulf of Guinea, the monthly precipitation totals were normal.
In Kazakhstan, the precipitation amounts were close to normal in the west but very scarce in the east – only a few tens of percents of the normal value. In the republics of Central Asia, the precipitation figures were normal or increased. Showers hit Uzbekistan. Water collapsed the dam of the water storage basin and flooded a number of human settlements. In the south of the Republic, the monthly precipitation amount in May was 2-3 times greater than normal.
Eastern Europe drowned in rains. Their monthly totals exceeded the normal values by 1.5-2.5 times everywhere from Poland to Greece and by three or more times in Ukraine. Snowfalls still occurred from time to time in the north of the continent. In the west, a number of heavy showers caused huge disasters even though the monthly precipitation totals were small. Torrential rains in the north of Italy partially flooded Milan: the streets of the city looked like Venetian canals. Residents of France were also affected by floods. In twelve hours, 200 mm of rain fell in some places, the monthly rainwater amount of 60 mm was reached in Paris, and up to twice the normal monthly amount of 100 mm was observed in Cannes. In Spain, the precipitation totals varied in a wide range yet resulted in the normal figure after monthly averaging over the country. However, this figure was twice exceeded in Andalusia, Aragon and Catalonia, whereas the precipitation was scarce in the north-east and south-east of the country. It was completely dry in Great Britain and Ireland. The precipitation amounts were about 50% of the normal value on average in the whole UK or just 15-20% in some areas; in certain locations, no precipitation at all was seen for the second month in a row. This May was one of the driest in the history of England. The most severe drought since 1976 was observed in the north of Ireland.
The precipitation in the east of the US was normal or above-normal everywhere from the Atlantic Ocean to the Rocky Mountains and Texas. The same was true for the north-west of the country. In the state of Michigan, rivers overflowed and flooded the roads, houses and fields due to heavy showers that were recognised as the record-breaking ones. More than 100 mm of precipitation, i.e., more than the normal monthly amount, fell in two days. The precipitation amount in Chicago for the same time interval was even larger, namely, 210 mm: this is twice greater than the normal value. In the south, heavy showers in the state of Florida inundated Miami and its surroundings, while in the north, a snowfall in the state of New York that occurred in the first decade became one of the most overdue in the history of meteorological observations. The south-eastern states received very little atmospheric moisture, and some regions did not receive it at all.
Heavy rains took place in the countries of Central America and the Caribbean. They caused major floods in Honduras, Guatemala and Salvador and raised the river level by 2.5 m. Up to 100 mm of rainwater fell per day. In Cuba, 120 mm of moisture poured down for an interval of several hours.
The weather in Mexico was dry in the north and wet in the south. In most of Canada, this month was dry, and the precipitation amounts were normal or above-normal in Quebec along the Atlantic coast and in the provinces of Saskatchewan and Alberta only.
In Moscow, this May was the wettest in history. The monthly precipitation total was 156 mm, or 301% of the normal value, which is 13 mm greater than the previous maximum value recorded in 1976. In addition to the record-breaking monthly precipitation, new daily maxima were also set. And the whole spring in the capital also was rich in precipitation. The total amount of precipitation for the three months was 235 mm, which is the second highest value in the history of meteorological observations. The precipitation amount in spring was even greater in 1976 only, namely, 244 mm.