An egg-sized hail and a tornado: Are we facing new supercell storms?

Last year, we all got acquainted with the supercell storm, which is still feared, and the director of the Republic Hydrometeorological Institute (RHMZ) prof. Dr. Jugoslav Nikolić tells "Blic" that the global temperature increase can certainly contribute to the increase of such storms.

He explains that supercell storms have occurred in Serbia before, that we did not encounter them for the first time last year. He says that only they are capable of producing large hail with a diameter greater than 5 centimeters, but also a tornado, which does not occur with other types of thunderclouds.

How a supercell storm is being formed

It is possible to successfully forecast 3 to 5 days in advance which region will be hit, and a warning for a specific location is issued only a few hours in advance.

According to Prof. Dr. Nikolić, for the formation of supercell storms, it is necessary to raise moist, warm and unstable air in an atmospheric environment in which there is pronounced vertical wind shear, which we can observe in terms of direction and intensity.

"The most important is the wind profile from the Earth's surface up to a height of six kilometers. Wherever in the world the aforementioned conditions are met, a supercell storm can occur. There have been such storms in our climate before, but certain trends in climate elements can cause their number to increase. All the time it gave strong hail and hurricane-like winds," says Professor Dr. Jugoslav Nikolić.

The length of the path of moving clouds was then more than 1,000 kilometers, the width about 30 kilometers, and the recorded damage from hail in Vojvodina alone amounted to 11 percent of the gross national income of the northern province.

"The year 2014 was also extreme when, in addition to drastic rainfall, which caused floods in May, the whole spring and summer was marked by a surplus of rainfall. Two years later, in June 2016, a supercell storm, which developed over Belgrade, caused a large hail and a tornado in Pancevo, and then it moved through Banat, Romania and Ukraine all the way to Russia, where the cloud finally weakened. The spring and summer of 2023 will also be remembered in the list of years with a large number of weather disasters, especially in the north of Italy, in western and central parts of the Balkans, as well as in the Alps," says the director of the RHMZ.

When is the earliest a supercell storm can be forecast?

According to Prof. Nikolić, from single-cell and multi-cell thunderstorms, supercells are distinguished above all by the rotating updraft of air, which occurs only in atmospheric environments with strong, pronounced vertical wind shear.

"The rotating updraft allows these storms to have a long life. They are the only ones capable of producing large hail larger than 5 centimeters in diameter, but also a tornado, which does not occur with other types of thunderclouds. To what extent will there be supercell storms in the coming season, it is difficult to estimate in advance, due to the complexity of the atmospheric conditions that are necessary for their formation. The global increase in temperature can certainly contribute to the increase of such storms, but their number varies from one season to the next. It can be successfully forecast 3 to 5 days in advance, if we are talking about forecasts and warnings by region. For specific locations, warnings are issued with the help of radar and satellite observations several hours in advance," says Nikolić.

Thunderstorms according to the calendar

A thunderstorm system is sweeping through Serbia these days. Professor Nikolić says that this year, thunderstorms began to occur in accordance with the calendar.

"As a rare occurrence, thunderstorms can also be observed in winter, but spring and summer are the seasons when the atmospheric conditions, in terms of temperature, humidity and instability, are the most favorable and optimal for their occurrence and for their frequent occurrence," he says.

He says that the RHMZ, according to the adopted Conclusion of the RS Government, has carried out all preparatory actions in accordance with the Law on Hail Defense, and that 24,012 anti-hail missiles have been provided.

"In 2024, defense will be carried out on 7,758,900 hectares, of which 5,108,177 hectares are agricultural land. Currently, a total of 24,012 anti-hail missiles are provided, which is the optimal supply of launch stations with missiles. The goal of defense is to reduce the risk of hail, because hail is an elemental disaster that cannot be prevented anywhere in the world. We do everything possible to reduce the damage in accordance with the profession, since there is no absolute protection in the world, ranging from 35 to 60 percent, and here in Serbia it exceeds 70 percent," says the director of RHMZ, Prof. Dr. Jugoslav Nikolić.