It does amaze me how long gliders can stay up, in the UK, which doesn't have an awful lot of mountains
I remember flying over Albania (basically, Croatia to Crete) and at one spot, FL170 or so, holding altitude on autopilot, our IAS went up from ~ 100kt to about 140kt. The nose came down, obviously. Clearly there was a massive updraught there. It lasted about 10 mins. It was totally smooth. It was there a few days later on the same route. The mountains were about 8000-10000ft high.
If you were there with a glider you could have just sat there for ages, soaring to some silly height, maybe FL300 plus.