Devastating floods in Georgia

By Ivan Smiljanic (DHMZ )

Overflowing rivers in Tbilisi caused flooding and landslides in the centre of the Georgian capital, leaving the city devastated and occupied by the animals who broke out of the local zoo. At least 19 people were reported to have died.

The weather conditions that led up to the flooding were a series of convective rainfall events occurring for a few days.

The favourable conditions for these convective activities were connected to an upper level trough that slowly approached the region from the west — shown by the green isolines of geopotential height at 500hPa pressure level (Figure 1).

The same image contains the black isolines of MSLP (mean sea level pressure) overlaid on a SEVIRI 10.8µm infrared image. At the lower levels there is no prominent pressure pattern as there is aloft.

The downpour which might have caused the rivers in the area to overflow was a relatively small and short convective event that occurred on the evening of 13 June, as shown in the Meteosat-10 infrared animation.

Although the infrared imagery from geostationary satellites reveals that the position of the storm was north of the capital, parallax correction needs to be taken into consideration — meaning that the true position of the storm is approximately 10–20km south of the position on the image.

Figure 2 reveals this parallax effect by presenting the same scene from the two satellites, at the same time, positioned over two different points of the Earth’s equator — Meteosat-7 (Indian Ocean) and Meteosat-10 (Atlantic Ocean, Gulf of Guinea).

The measured difference between the same core of the storm, seen from the two different satellites, is approximately 25km.