There usually seem to be some Loons over South America, sometimes Puerto Rico area and there are about 14 over Australia (north and north west) right now. On FR24, set an altitude filter to say 45,500-MAX ft and they stand out clearly. At present MAX seems to be about 65,000 and perhaps these balloons may sometimes be above that.
Here is a launch facility in USA.
https://goo.gl/maps/VYjibCuN9f32
