Features of the “Supercell Storm” that hit Halkidiki (video)

South Halkidiki and the peninsula of Kassandra came in the center of a so-called “supercell storm*” with extensive rainfalls and extremely strong lightning activity. At the same time, the peak of the storm surpassed mayor layer of the Earth atmosphere, the troposphere, reaching height of over 12.5 km.

Height of the supercell storm cloud

Very extensive lightning activity

Storms of such great horizontal and vertical growth and intense lightning activity are associated with strong winds and devastating effects, such as those Halkidiki experienced on Wednesday evening, July 10, 2019.

During the evening hours of Wednesday, July 10, 2019 and more particularly during the period 21: 00-00: 00, storms of particular gravity, accompanied in most areas by fierce winds and in some cases by hail of large dimensions, affected regions of Central and Eastern Macedonia.

The strongest phenomena have been identified in the prefecture of Chalkidiki, where 7 people, six foreign nationals and one Greek, were killed, 120 people were injured and large devastation occurred.

The turbulence of the winds, which was the main cause of the loss of human lives, is due to the very strong winds of the violent invasion of the cold front in Northern Greece and to the very strong downward streams accompanying the storm cells.

The following map shows the intense electrical activity was recorded by the National Disaster Detection System of the National Observatory of Athens / meteo.gr “ZEUS” in Northern Greece.

Wind speed: Stratoni 100 km/h at 10:30 pm, Polygyros 68 km/h at 10:20 pm, Nea Mihaniona 85 km/h at 9:30 pm

It is noted that the wind speeds presented are lower than the wind speeds that accompanied the storms, as the strongest phenomena occurred in a very small area where there is no coverage by a meteorological station. In addition, data from some stations such as Cassandria are not yet available due to power outage.

Despite the fact that summer storms and night bourinia** are common in the northern parts of Greece, the phenomena that occurred on Wednesday are characterized as “extreme” because  they occur with low repeatability. It is characteristic that similar phenomena hit central and northern Greece on 20-21 July 1983, resulting in extensive disasters and the death of 9 people in Thessaloniki and Kavala.

Video: Satellite pictures of the Halkidiki storm from Wed noon until Thu morning

It is noteworthy, however, that the extreme phenomena (supercell storm)of Wednesday were predicted in time and with great accuracy, both in terms of the cold and hot convergence of gas masses over Northern Greece, and in the most affected areas.

In the light of the bad weather and the casualties behind it, as well as the experience we have gained from the major disasters in Mandra and Attica, it is now clear that we need to create intelligent systems to alert citizens to the emergence and development of intense / dangerous phenomena. (source: meteo.gr)

Head of the Greek National Meteorological Service, Thodoris Kolydas, told media that inside the storm, wind was reaching a speed of over 320 km/h even 400 km/h.

Professor Christos Zerefos from theResearch Center for Atmospheric Physics & Climatology Academy of Athens, said that waterspouts were built inside the storm and that was that was the explanation that vehicles were whirled in the air and found meters away.

*Supercell is a thunderstorm characterized by the presence of a mesocyclone: a deep, persistently rotating updraft. For this reason, these storms are sometimes referred to as rotating thunderstorms. Of the four classifications of thunderstorms (supercell, squall line, multi-cell, and single-cell), supercells are the overall least common and have the potential to be the most severe. Supercells are often isolated from other thunderstorms, and can dominate the local weather up to 32 kilometres (20 mi) away. They tend to last 2-4 hours.

**Bourini in the common nautical language is generally characterized by the sudden change of weather, of relatively short duration, with increasing wind intensity, accompanied by rain, storm rain, lightning and thunder.

PS The government wants now to activate the European emergency phone number <112>.