The merger of two cyclones can create a "super cyclone" over Moscow. What you need to know

Precipitation is expected to increase in Moscow and the region next weekend due to the convergence of two atmospheric vortices. However, forecasts for the arrival of a "rare super cyclone" and extreme rainfall require clarification. What awaits Muscovites this week and next is in the Izvestia article.

Super cyclone in Moscow, the Fujiwara effect and what is really happening with the weather

Evgeny Tishkovets, a leading specialist at the Phobos weather center, reported on extreme rains due to the formation of a super cyclone over the Central part of Russia on July 8 in his Telegram channel. According to the forecaster, the reason for the sharp deterioration in the weather will be the Fujiwara effect, a rare phenomenon in which two cyclones merge and form a powerful vortex with a single center that rotates counterclockwise.

The expert noted that Cyclone Bernadette, which originated on the wave of an atmospheric front, and its "baric counterpart" coming from the Caspian Sea are moving towards the Moscow region.

"Both atmospheric vortices will move deep into the Russian Plain and, once close enough, will begin to interact in a counterclockwise rotation around each other. As a result of swirling around a common center, by the weekend they will merge into one huge regenerating supercyclone with a "core" over Central Russia, where heavy rains are forecast for Saturday and Sunday, with a total rainfall of up to 3/4 of the monthly norm or 5-6 buckets of rainwater per 1 square meter," wrote Tishkovets.

In turn, Tatyana Pozdnyakova, chief specialist of the Moscow Meteorological Bureau, noted that the Fujiwara effect is solely related to the interaction of tropical cyclones or hurricanes. According to her, this phenomenon is observed in areas where powerful tropical systems are forming, for example, in the oceans, when two cyclones begin to converge and affect each other's movement.

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"This effect applies to hurricanes or tropical cyclones. We don't have them right now. When we have a dangerous convergence or unification of tropical cyclones or a hurricane that goes out to sea, say, from Central America, and unites with a tropical cyclone or typhoon in the Sea of Japan, then this effect works. This effect occurs after the convergence or unification of powerful tropical formations. We don't have any powerful formations right now," the weather forecaster noted.

According to her, weather changes are associated with the usual processes for temperate latitudes — the movement of cyclones and their possible interaction.

Which cyclones will bring rain to Moscow this weekend

According to experts, the cause of the deterioration of the weather will be a combination of two atmospheric systems. One cyclone will come from the west, now it is moving through the Baltic region towards Belarus. The second vortex is developing in the Caspian Sea region.

As Pozdnyakova explained, these systems may merge east of the Moscow region. As a result, an extensive zone of cyclonic activity will form in the region, which will lead to an increase in precipitation.

At the same time, the specialist stressed that such processes are not uncommon in the Russian territory. The convergence of Atlantic and southern cyclones regularly occurs in the central part of the country and in itself does not mean the occurrence of extreme weather.

According to her, the intensification of rains in this case is due to the interaction of different air masses. Cooler air from the northwest will meet with a warm and humid stream coming from the south.

Rains in Moscow: what will be the amount of precipitation

Despite widespread reports of heavy rains, meteorologists do not expect extreme rainfall in Moscow. According to experts, the rainy weather will indeed continue, but it will have the usual character for July.

Forecaster Pozdnyakova explained that in meteorology, a downpour is a situation where more than 15 mm of precipitation falls in 12 hours. Currently, such an indicator is not forecasted for Moscow.

"Compared to what we are currently seeing, there will be more rain over the weekend. So far, heavy rains are in the category, and even more so showers, we do not predict such showers. Because the rapprochement processes are still being formed. We don't even know how intense the Caspian cyclone will be," Pozdnyakova said.

At the same time, in some areas of the Central Federal District, a noticeable amount of precipitation may accumulate in a few days. According to the forecaster, up to half of the monthly rainfall is possible in some places.

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However, this is not about a short-term heavy downpour, when a significant amount of water falls in a few hours, but about a more even distribution of precipitation over several days. This scenario is considered typical for the summer period.

Why forecasts need to be clarified

Earlier there were reports that up to 80% of the monthly precipitation may fall during the passage of the cyclone. Forecasters consider such estimates to require careful consideration, since the amount of rain depends on a particular territory and can vary significantly even within the same region.

Pozdnyakova noted that the maximum figures may be recorded in certain areas, but this does not mean a similar development of events directly in Moscow.

The peculiarity of the capital lies in the fact that a large amount of precipitation in a short period has a greater impact on the urban infrastructure. Due to the large number of paved surfaces, the water does not always have time to leave quickly, which can lead to local flooding.

At the same time, according to the expert, the current forecast does not indicate the likelihood of such scenarios. Precipitation is expected to fall gradually, so it does not pose a significant threat to the city.

Rainy weather in Moscow is associated with the peculiarities of July

Meteorologists draw attention to the fact that an increase in the amount of rain in the middle of summer is not an unusual phenomenon for the metropolitan region. July is traditionally considered one of the rainiest months of the year.

According to Pozdnyakova, during this period, situations often arise when a significant amount of precipitation falls in a few hours. However, such phenomena are related to specific atmospheric conditions and do not occur with every passing cyclone.

"In places, up to half of the monthly precipitation may fall in the metropolitan region or in the central region, but this happens very often for July rains. July is characterized by the fact that precipitation falls for 3-4 hours this month, and then there is no precipitation," she said.

The current situation is developing according to the same scenario: the rains will be mostly short-term, and their intensity will remain moderate. At the same time, cloudy weather may persist for several days.

The forecaster noted that residents of Moscow should take into account the change in weather conditions, but there is no reason to expect abnormal showers or the arrival of an unusual "super cyclone".

When will the rains end in Moscow and the weather change

According to preliminary forecasts, the most noticeable impact of the cyclonic zone on the metropolitan region will be on the weekend and the beginning of next week. After that, the atmospheric vortex will gradually weaken, and the pressure will increase.

Pozdnyakova said that in the period from about July 14 to July 23, more stable weather is possible under the influence of an area of increased atmospheric pressure. Rains in this scenario may become less frequent and less intense.

At the same time, the expert stressed that forecasts are regularly updated, as atmospheric processes can change rapidly. In Moscow, short-term forecasts are reviewed every six hours, which allows new data to be taken into account.