Thanks for your reply. I did some further investigation, see attached screen shot. Pic shows a sample location for today 13h00 LT. Graphical estimation from sounding, ECWMF) gives a thermal high of about 1500m at 23°, CCL 2841m , windy computation 1900m. Meteoblue (sorry to mention concurring source) provides ICON-D2 sounding which let me to estimate approx 1000m. Now am a little puzzeled but from experience I think the later is more realistic.
thermal map_temp _Eldingen.JPG sounding_stueve_Berl_Heide_16Mai_1300.png !