128
The image I’ve included is surface level radar (top left) to radar at 15000ft (bottom right) and is truly incredible. You almost never see such obvious and large scale cyclonic activity like this that is both so wide and so high up into the atmosphere. Wind speeds of over 200mph
Tornado circulation continues above the cloud base, far up into the parent storm.
I saw one far away while visiting family in the Midwest as a kid. Cloud base was 2500m that day according to weather records, so at least 8000ft for a random one I happened to see.