MAIN WEATHER AND CLIMATE TRAITS IN THE NORTHEN HEMISPHERE AS OF AUGUST 2019
Air Temperature
Cold July weather seemed to get stuck for long in the European Territory of Russia. It dominated in the ETR for the whole first decade of August. Numerous events of record-breaking cold were reported in the north-west and midland parts of Russia. Everywhere from the western border to the Urals, the decade-averaged air temperatures dropped below their normal values, by 2° in most of the ETR and by 4-6° in the South-West Federal District and in the north of the Central Federal District.
Some or the other way, the weather became a bit warmer in the second decade. But in the north, it remained colder than ever, with ground frosts observed for the first time. Low temperatures were also recorded in the Lower Volga Region. Yet, the temperature distribution in most of the ETR was close to normal, or showed a 2-3° increase in the south.
However, cold weather returned in the third decade again. In the Central Black Earth Region and in the Volga Region, it came to unprecedented levels. Frosts were reported in many areas including the Moscow Region. As a result, the monthly-averaged temperature was 1-2° lower than usual in the North-West and Volga Regions and in a large part of the Central Federal District. It should be noted that cold August is not very rare in this part of Russia: as a rule, it happens once in 5-10 years.
A completely different picture was observed beyond the Urals. In Siberia, the weather was hot almost the whole month. In the Krasnoyarsk Territory, Kemerovo Region, Republics of Tyva and Khakassia, and in the Taimyr, new daily temperature maxima were recorded. In the outcome, this August in Siberia became the second hottest after August 1998 in the history meteorological observations.
In the Far East, the weather varied. All over there, it was abnormally cold in the first decade, with the anomalies reaching -2° or more in the north of the Khabarovsk Territory and in the Magadan Region. Then, the weather equalised and even became abnormally warm in the Kolyma and Chukotka. In overall, the monthly-averaged air temperature was close to normal or even slightly higher in most of the Far East -- save for the Primorye Territory, Sakhalin and the south of the Khabarovsk Territory where it was somewhat colder than usual in places.
August closed up the calendar summer to reveal that the summer was colder than normal in the north of the ETR, in most part of the Volga Region and partially in the Central Federal District, but much warmer in Siberia and in the north of the Far East – by up to 3-4° in places. In the Siberian and the northern Far East Federal Districts, the average temperatures in summer regained their record-breaking values previously noted in 2016 in Siberia, and in 1991 or 2010 in the north of the Far East. In contrast, this summer was unpleasantly cold in the south of the Far East (the Primorye Territory and Sakhalin). As for Russia as a whole, the average summer temperature occupied a place at the boundary between the first and second tens of highest values in their ranked list.
In East Asia, August was hot. The normal monthly-averaged air temperatures were exceeded by 2-3° in places, most remarkably, in Mongolia and in the north and south of China. A new temperature maximum was set in Hong Kong, and ever-high temperatures were recorded in Japan. At the same time, August was colder than usual in the south-east of China close to the Russian border. Still, there was more heat than cold in China, and August 2019 was the fifth among its hottest counterparts in the history of meteorological observations.
Hot weather dominated the Near and Middle East,. The monthly-averaged air temperature exceeded its normal value by 2-3° in many regions. Yet, August was 1-3° colder than usual in Oman and Yemen in the south of the Arabian Peninsula.
In North Africa, the air temperature turned out to be above the normal climatic value: by 2-4° in the countries on the Mediterranean coast (Egypt, Algeria and Tunisia), or by about one degree to the south of Sahara.
In Europe, the weather was still hot. New temperature maxima were measured here and there from Spain to Ukraine. The air could heat up to +30-35° and above. At the beginning of the month, the invasion of cold air in the Eastern Europe caused new unprecedented colds in Ukraine and Belarus. The anomalies of monthly-averaged air temperature in most of the continent excluding Great Britain and the Scandinavian and Baltic countries were +2-4°. As for the whole continent, the average temperature of August was the fourth highest in the meteorological chronicle.
In the North American continent, the monthly-averaged air temperature was generally normal. In the USA, it was much warmer in the west and south of the country; in Mexico, in the north; in Canada, in the polar north-western regions. There, the anomalies of monthly-averaged air temperature reached +2-3°. On the other hand, August was colder than usual in the west of Canada, as well as in the Rocky Mountains and the Midwest of the USA. The monthly-averaged air temperature in the north-western states from California to Colorado and New Mexico hit the Top Five of the highest values in the history of meteorological observations.
The Arctic was very hot this month. Its average temperature was 2° above the normal value – the highest value in history, as much as half a degree higher than the previous one recorded in 2007.
As previously reported by the Hydrometcentre of Russia, the average air temperatures of June and July 2019 in the Northern Hemisphere were the highest in history (or duplicated the highest ones achieved before). The same happened in August. Upon that, the summer of 2019 turned out to be the hottest in the Northern Hemisphere for almost 130-year history of regular meteorological observations on the planet.
Conforming to the trends of the last years, this achievement was most largely due to the southern and temperate latitudes. From Taimyr to Chukotka and in Eastern Siberia, the average summer temperatures in Russia exceeded the normal values by 2-4° or more. The same was true in the Arctic region in eastern Canada, in Greenland and in Alaska. In most of Europe, in the Near and Middle East, in Transcaucasia, in the northern African countries and in Mexico, the normal values were also exceeded by 2° or more.
In the Arctic and, exceptionally, in Alaska, it was the hottest summer in history, while in Siberia, in the north of the Far East and in the north of Africa, the average summer temperatures were the same as their maxima set out before.
In Moscow, the average air temperature in August was +16.4°. This matches the normal value. The air temperature averaged over the whole summer was also close to normal.
Ocean surface temperature
As the positive SST anomalies of the Pacific Ocean in the Northern Hemisphere continued growing, the average anomaly over the whole surface reached its absolute maximum. Considering that this occurred in June and that the average SST in the Pacific became the second highest (after 2004) in July, no wonder that the average surface temperature of the Pacific Ocean in the Northern Hemisphere for the summer of 2019 became an absolute positive extremum, exactly as in the case of the air temperature in the Northern Hemisphere.
Indeed, the surface of the Ocean in the Northern Hemisphere heated to unprecedented values in August. In a large part of the water area in the east of tropical and temperate latitudes, the average SST exceeded the normal value by 2-3° or more. The SST anomalies in the Bering Sea and in the neighbouring water areas of the Arctic Ocean (Chukchi and Beaufort Seas) reached +4-5° and more.
As for the Atlantic Ocean in the Northern Hemisphere, a completely different picture was observed. There, even though the average SST anomaly also rose compared to the previous month and became the largest in the current year, it was much less than in the past. Along with large positive anomalies (up to +2° and more) off the coasts of the USA and Canada, negative anomalies took place in the east of tropical latitudes, along the coast of Africa, and especially in temperate latitudes from Newfoundland to Europe.
Abnormally warm water was everywhere along the Northern Sea Route.
Precipitation
A spot-like precipitation pattern has long been recognised as an inherent feature of the north-west ETR region. This is readily backed by the precipitation distribution map plotted this August. Indeed, given just 60% of the monthly totals in the Leningrad Region, the neighbouring Novgorod Region surprised at twice the normal figure, and the Republic of Karelia with its roughly the same 60% precipitation quantities was beaten at 1.5 times the normal precipitation in the Republic of Komi eastwards. But the major amounts in the ETR were shared by the south and east of the North-East, the north of the Central and the most part of the Volga Federal Districts with the monthly totals 2-3 times the normal values in some places, or more. Sometimes, the precipitation recorded therein broke all daily or even monthly expectations (as it was in the Arkhangelsk, Pskov and Perm Regions or in the Republic of Komi). Twelve hours were quite enough to produce 80 mm of rain or more. Yet, the precipitation was scarce from the Black Earth Region to the Caucasus in the south of the ETR, and no rains at all were bestowed to certain regions of the North Caucasus.
In the Urals, the precipitation rate was either normal or slightly higher than that. In Siberia, the excess precipitation was recorded in Taimyr and in the south of the region (e.g., the southern areas of the Krasnoyarsk Territory, the Kemerovo Region, and the Altai and Khakassia Republics). The monthly totals in these areas were either normal or increased. The rest of Siberia -- and the Far East alike -- lacked precipitation, excluding the southern areas and the Magadan Region, where the normal precipitation amounts were noticeably exceeded: by 2-3 times in certain places, with the heavy showers resulting in up to 70 mm of rainwater. This exacerbated the already flood-hazardous situation with the rivers. Vast high water beds were flooded, and a new record-breaking amount of precipitation in August was measured in Vladivostok.
A lot of precipitation came to the north-eastern and central regions of China. This was due to both the summer monsoon and the tropical cyclones reaching these areas. Sometimes, the monthly totals where 2-3 times above their normal values in places. In the other territories, rains were rare excluding the province of Guangdong where the monsoon did its best covering the whole South-East Asia by the way. In Myanmar, the rains caused a landslide that killed dozens of people.
An Indian monsoon was still flooding the country. All India was flooded with the heaviest rainstorms. The monthly water amounts in the south and in the centre of the country were two or more times greater than normal, a bit less than in the north-east Pakistan.
The weather in the Near and Far East was quite a different story. A rainy place in August was hard to find in this area. The readings in many meteorological stations in this region showed zero in the "monthly precipitation" column. Hot and dry weather helped the sand storms to spread all over around, markedly, across Iran this time. And the south-west of the Arabian Peninsula and the eastern regions of Turkey received normal or occasionally larger amounts of precipitation.
No regions in Central Asia were endowed with rains excluding the northern or eastern Kazakhstan as well as Kyrgyzstan and the west of Turkmenistan. There, the monthly precipitation amounts reached the normal value or exceeded it in individual places.
Rains were pouring in the west of the African continent. Commonly, their monthly totals were close to normal yet 1.5-2.0 times larger in some places in Mali, Niger and Chad.
Most of Europe was almost rainless in August. The normal rainfall amounts were only observed in the north of the continent (Norway, Sweden, Great Britain and Ireland) and in Belarus, Bulgaria, German and Spain. In certain areas of Spain, the quantity of atmospheric moisture was 1.5-2.0 times the usual monthly amount.
The monthly precipitation rates in the northern and central provinces of Canada were close to normal or two times greater in places, but the west and the east of the country remained dry every so often. In the USA, dry weather prevailed in the south-west where no rains were recorded in particular areas. The states of Utah, Colorado, Arizona and New Mexico hit the Top Ten of the driest Augusts for the whole history of meteorological observations, and the Top Five of the driest summers in the overall. As of this August, the central and eastern regions of the country received their normal or larger amount of precipitation. In certain stations of Nebraska and Kansas, the amounts were exceeded by 2-3 times. It was "sloppy" in the north of Mexico, but the weather in the south of the country was dry.
Moscow received 57 mm of rain in August, which is 74% of the normal quantity. As to the whole summer, this amounted to 190 mm, i.e., the same 74% of the normal value.