The most prestigious gas balloon race in the world is the annual Gordon Bennet Cup
Pilots stay aloft for several days and might cross the continent
To get an idea, here's a video of the tracks flown this year:
The teams have (and need!) a ground crew which advises pilots on weather and tactics
This year, windy and traj were part of the games - in the ground support for the Belgian, Spanish and US teams - Kolja Packard wrote up a field report (he was part of the support team and worked the weather forecasts):
(this is still german-only, I will post an english translation shortly and notify here):
In particular, have a look at the very first image in the blog post - this was the track forecast 20 hours (!) before takeoff
compare that to the youtube video above - the match is amazing!
Many thanks to Kolja in writing this up!