MAIN WEATHER AND CLIMATE TRAITS IN THE NORTHEN HEMISPHERE AS OF AUGUST 2020

Air Temperature

In most of the ETR, cool July weather preserved for the first half of August. Even frosts were observed sometimes: hardly surprising for anybody in the Murmansk and Arkhangelsk Regions or in Karelia, they definitely were rare guests in the areas such as the Moscow Region. The weather was warmer than usual in the North Caucasus and in the Kaliningrad Region only: there, new temperature maxima were recorded. In the second decade of August, the decade-averaged temperature anomalies reached -2…-3° in the Volga Region. The warmth came forth as late as on the twenties of the month, and the closer to the end of summer, the higher the temperature. And on the last day, new daily maxima were recorded in the midlands. In the third decade, the normal temperatures were exceeded by 2-3° or more in most of the ETR.
Hot weather prevailed in the Urals and Western Siberia from the first days of August. Sometimes, the thermometers readings rose to record-breaking levels in excess of +30…35°, and even crossed the 39° mark in Yekaterinburg. There, the average temperature was 3-7° higher than normal in all decades. Further to the east, cold weather prevailed in the Far Eastern Federal District. New daily temperature minima down to -8° were observed in Yakutia, and frosts, in Primorye and in the Khabarovsk Territory. The anomalies of decade-averaged temperatures reached -2…-3°. The Far North and the Arctic islands of Russia were the only exceptions to enjoy extraordinary warmth for almost the entire month. The ever highest temperatures were recorded in the areas from Novaya Zemlya to Chukotka. In some places, records were set for ten or more days in succession.

The outcomes of such alternation of heat and cold over the spaces of the vast country were above-normal monthly-averaged temperatures 2-6° higher than the normal value in the Urals, in Siberia and on the Arctic islands and, conversely, subnormal temperatures in the Far East and partly in the Volga Region, the Vologda Region and the Republic of Komi. In Siberia, this August became the second warmest in history, yielding to August 1998 only.
Summer 2020 was among the very warm ones in Russia: its average temperature was the fourth highest in the meteorological chronicle since 1891. The average summer temperature was even higher in 2016, 2010 and 2012. The season-averaged value was also higher than normal almost all over the country: mostly by 1-3°, and by up to 3-5° in the north of the Urals, Siberia and Yakutia, and on the Arctic islands. This summer turned out to be colder than usual on Sakhalin and in individual regions of the Khabarovsk and Primorye Territories.
The weather was hot in the east of China, in Korea and in Japan. There, the air temperatures were exceeded by 2-3 or more degrees in places. New temperature maxima in excess of +40° were recorded on each next day for more than a week in Japan. A similar situation took place in Shanghai (China), but the temperatures were slightly lower: +30° or more.
An even more fierce heat occupied the Near and Middle East, albeit that with occasional penetration of colds that even brought new temperature minima to Transcaucasia. Still, the monthly-averaged temperatures were 2-4 or more degrees higher than normal in this region.
In the republics of Central Asia, the weather was hot all August. The thermometer readings in Tajikistan and Turkmenistan were sometimes above the previous achievements, and the temperature in Kazakhstan exceeded +35°.
In North Africa, the monthly-averaged air temperature was two or more degrees higher than normal in the Mediterranean countries, and close to normal elsewhere excluding the Horn of Africa where this August was somewhat cooler than usual.
Hot weather spread throughout Europe where new daily temperature maxima were set in many countries. Moreover, these maxima were being recorded for several days in succession. In the UK and in France, the temperatures approached +40°, and in the Scandinavian countries to the north of them, exceeded +30° from time to time. In Cyprus, this August became the hottest
one in the history of meteorological observations. Across the entire continent, the monthly-averaged air temperatures were above-normal, most notably, in the countries of Central, Eastern and Northern Europe where the anomalies reached +3…4° or more. August 2020 was the third warmest in the history of the continent, immediately after August 2018 and August 2003.
This August was also the third warmest in the USA, surpassed by August 1983 and August 2011. Although the monthly-averaged air temperature in most of the country roughly matched the normal value or was even a bit lower than that in places, such high rank was achieved due to the western states where this temperature was 2-3 or more degrees higher than usual. The major contributions in this regard were made by the states from California to Colorado and New Mexico: along this way, August 2020 was the hottest in history. In California, a new temperature maximum of +54.5° was established for our planet in the Death Valley. Abnormal heat provoked the development of numerous fires. In Canada, the monthly-averaged air temperature entered the Top Five of the highest values for the entire history of meteorological observations. An approximately normal temperature in most of the country went side by side with a large positive anomaly in the east and the north (up to +3° and more).
High temperatures across the polar region bestowed the Arctic with the second warmest August in history and, at the same time, with the hottest summer ever observed there.
In overall, this summer in the Northern Hemisphere was incomparably warm. Its average temperature exceeded the previous record-breaking value set in 2016. Apart from the Arctic and Russia, the past summer was very warm in the USA, in Canada, Europe and China, as well as in the Near and Middle East. In these territories, the anomalies of the season-averaged temperatures exceeded +2..3° or more. The average temperature of summer was above-normal almost everywhere in the Hemisphere. The exceptions were the Hindustan Peninsula where active monsoon clouds prevent solar heat from warming-up the ground, and certain water bodies of the Atlantic, Indian and Pacific oceans.
In Moscow, the average temperature in August was +17.6°, corresponding to an anomaly of +1.2°. Summer was also warmer than normal, by 1.3°.

Ocean Surface Temperature

The surface temperature of the Pacific Ocean in the Northern Hemisphere was very high: almost one degree higher than normal on the average. Besides, such high temperature preserved there for the entire summer so that this summer became the warmest one in the history of SST observations. In August, anomalies of +1…2° or higher spread over the whole water body of the Ocean in tropical and temperate latitudes. The monthly-averaged SST was below normal along the coast of North-East Asia only (in the Yellow Sea, in the Sea of Japan and partly in the Sea of Okhotsk). Water was abnormally cold along the entire equatorial belt, pointing to rapid advance of the South Oscillation towards the cold episode, viz., La Niña. The very high SST in the western part facilitated the development of typhoons.
A similar pattern was also observed in the west of the Atlantic Ocean where the average SST exceeded its normal value by 1-2° or more along the coast of North America and much further to the east of it. Water was also extremely warm in the north, namely, in the Barents and Kara Seas (with anomalies reaching +5° or more). The water temperature was considerably higher than usual in the marginal seas: in the Mediterranean and Black Seas in the south, and in the Baltic and North Seas in the west. The surface of the Ocean was abnormally cold just in individual water bodies at temperate latitudes.

Precipitation

In August, the most important news about the rains in Russia was coming from the Far East overwhelmed with huge amounts of atmospheric moisture. In Primorye and in the south of the Khabarovsk Territory, the Amur Region, Trans-Baikal, on Sakhalin and in the south of
Kamchatka, the monthly precipitation totals were 2-3 times larger than normal in places. Up to 100 mm of rainwater or more accumulated there per day. Flooding was reported in a number of cities and settlements.
Likewise, heavy rains hit the Urals (Perm Territory, Sverdlovsk and Chelyabinsk Regions), North Caucasus and Upper Volga. There, up to 30-40 mm of daily precipitation was collected, and new daily maxima were recorded. The monthly precipitation totals exceeded the normal values by 1.5-2.0 or more times.
In Yakutia, Kolyma and Chukotka, snowfalls were no longer rare, and continued for several days without interruption in some places.
Yet, precipitation was scarce in most of Russia. It was especially true for the central and southern ETR or for the vast spaces of Siberia and Yakutia, with no noticeable precipitation whatsoever. Soil droughts were observed in the south of Western Siberia.
Before arriving at Primorye, typhoons unleashed their power onto the countries of East Asia: China, both Koreas and Japan. The downpours they brought caused devastating floods and landslides. In some areas of China, the flash flood became the most severe for the last 200 years. The water level in some parts of the Yangtze River surged by 5 m to result in the most catastrophic floods in the past 60 years. Heavy rains on the Korean Peninsula caused tremendous destructions and damage to agriculture. Up to 300 mm of rainwater fell in certain regions per day. Water washed away tens of thousands of hectares of agricultural lands. Railway communication halted from time to time because the tracks were flooded with water. Casualties were reported. The normal monthly precipitation rates in Korea, China and Mongolia were exceeded by 2-3 times in some places. In most of China excluding its south regions, the precipitation totals were above-normal. In Japan, the rain amounts were less than normal, but occasional heavy showers did reach the south of the country at the end of the month.
In the countries of South-East Asia, the precipitation amounts were larger than normal, by 1.5-2.0 times in places. Showers caused floods in the north and north-east of Thailand, bringing more than 200 mm of daily rainwater in some regions. Local meteorologists remarked that the precipitation rate during the monsoon season was exceptionally high this year.
In the Hindustan Peninsula, this monsoon was strongest for several recent years. Its heavy blow impacted the Indian states of Bihar, Assam and Rajasthan. Tens of thousands of people suffered, and some were killed. The motor traffic movement was interrupted. Up to 400 mm of rainwater was collected per day in certain regions. The water level in rivers crossed the critical marks. The city of Mumbai received 332 mm of atmospheric moisture during a single day. The normal monthly totals were exceeded everywhere in the country, by 1.5-2.0 times in places. Rains were even more plentiful in the southern regions of Pakistan where rainwater amounts 2-4 times the normal values were observed. The former capital of the country, the city of Karachi on the coast of the Indian Ocean, was seriously damaged. There, more than 200 mm of rain fell just in a few hours and flooded the whole city. That day in history of the city was the rainiest over the past 50 years. The total monthly precipitation amount in Karachi reached 484 mm, a figure that had never been seen before. Destructive torrential rains passed along Nepal where scores of people died in landslides and mudflows. In Bangladesh, monsoon rains resulted in suffering of about ten million of people. Floods created by these rains were deemed the most shattering in the past 20 years.
The weather was dry in the Near and Middle East. Almost no rains were observed there with the exception of Transcaucasia or the north-eastern Turkey, and of the south-west of the Arabian Peninsula. In the first case, more than 100 mm of rainwater fell in some regions in a few hours, leading to floods and numerous destructions, in particular, affecting the city of Batumi. In the second case, heavy rains in Yemen also caused flooding that brought damages to the city of Sana'a, the capital of the country.
In Central Asia, most rains came to the Central Asian republics and Afghanistan: there, the normal precipitation amounts were exceeded by 3-4 times. Heavy downpours caused flooding in the east of Afghanistan. Water flows swept away hundreds of houses and killed
dozens of people. The weather in Kazakhstan was relatively dry, but occasional heavy showers did take place in the north of the country. For example, 66 mm of precipitation fell in two days in the city of Aktau near the Caspian Sea: this is 11 times greater than the normal monthly amount.
In North Africa, rains were intensive to the south of Sahara only. The monthly precipitation totals all the way from Senegal to Sudan were either normal, or slightly increased. In Niger, the Niger River overflowed its banks after rains and inundated the city of Niamey, the capital of the country, destroying thousands of houses. Showers also caused floods in neighbouring Nigeria, Chad and Cameroon: tens of thousands of people suffered from this disaster in the latter countries. In the east of the continent, downpours in Sudan overflowed the Blue Nile and raised its water level by 1.5 metres. The situation became even worse after the breakthrough of the dam leading to catastrophic damages and to evacuation of thousands of people. The daily precipitation amount exceeded the normal value by nine times.
In the Scandinavian countries and in the east of the European continent, the weather was mostly dry, and Central Europe received approximately normal amounts of precipitation. Heavy rains targeted the south of the continent (Spain, Italy and Greece) as well as the UK and the north of France. There, the precipitation amounts were two or more times greater than normal in places. In the north-east of Italy, rains flooded the streets of Verona and badly damaged the vineyards. Snow fell in the mountains. In Spain, downpours flooded the central and southern regions of the country. Heavens provided a lot of celestial moisture: one day, they supplied 85 mm of rainwater in two hours. For a single day, heavy rains in Greece could bring the precipitation amount twice the normal monthly one. Pouring rains in England and Scotland caused floods, landslides and earth falls. The streets of Aberdeen were flooded. 150 mm of precipitation was collected in the south-east of England just for a couple of days. French Normandy submerged under water.
The weather was mostly dry in the western US from both Dakotas to Texas. In Utah, Colorado, Arizona and New Mexico, this August was the second driest in the history of meteorological observations. There, just a few percents of the normal precipitation amount accumulated for the month, and no precipitation at all accumulated in many places. On the contrary, rains in the east did their work well, and the normal monthly figures in many regions were exceeded by 1.5-2.0 or more times. Flooding occurred in Maryland after heavy rains. The southern and south-western regions of Canada received much precipitation, but the weather in the rest of the territory was generally dry. Heavy rains passed along the Pacific coast of Mexico resulting in floods and landslides. Up to 110-150 mm of precipitation accumulated daily in some places. The streets in the city of Pueblo changed into rivers. Some countries of Central America also suffered from downpours; in particular, 120 mm of rain fell in nine hours on the island of Trinidad off the coast of Venezuela.
In Moscow, 34 mm of precipitation, i.e., 44% of the normal monthly amount, fell in August, and 363 mm fell during this summer; the latter is the sixth highest result in the meteorological chronicle of the capital. For the period from January to August, the precipitation in Moscow amounted to 691 mm: this exactly matches the normal annual total. Now, each next millimetre (and quite a few of them are expected during the autumn months) will add to the excess above the normal figure. And if the precipitation amount would correspond to the normal value by the end of the year, then the year 2020 will be the wettest in the meteorological chronicle of the capital.