Radiosounding data

This image shows radiosounding measurement which took place at Ankara on 26 May 2006 at 00 UTC. Around that time a big convective cell developed near-by induced by orography, ahead of the front. We obtain tropopause at approximately -60°C at about 12 km height. The wind, especially above 3 km, shows south-westerly direction. Some of stability indices show a risk for severe convection. For example, Showalter index (SHOW) lower then 0 indicates that there is quite large possibility for thunderstorms.
The values of stability indices are presented at the right part of images, and more about some of them you can find here or in the chapter "Basics" in the “Manual of Synoptic Satellite Meteorology”

12 hours later, convective development within cold front near Ankara reaches its mature stage. Radiosounding measurement (not complete, probably because of the severe weather) shows potentially unstable atmosphere. Lifted index (LIFT) has negative value which indicate vertical motions, unstable atmosphere and a high chance of convection. Showalter index (SHOW) shows also negative value with high potential for thunderstorms. The pronounced backing of the wind with height indicates strong cold advection aloft which leads to further destabilisation of the atmosphere.

Radiosounding measurement at Isparta at 12 UTC shows unstable stratification, with the tropopause at -65°C at about 12 km height. Many thunderstorm indices show a high possibility of severe convection. Strong south-westerly winds through the whole atmosphere can be noticed.

Radiosounding measurement at Samsun at 12 UTC shows relatively stable stratification. The air above 3 km is relatively dry. At the moment prefrontal convection has not reached Samsun jet, and the other convective system still refrains over eastern Turkey. The strong backing of the wind with height in upper troposphere indicates strong cold advection aloft which leads to destabilisation of the atmosphere.