The ability for a hot airballoon to fly based on weather, particularly correlation of rain in the forecast. For example, if there is a 70% chance of rain you have a 30% chance the balloon will fly. Sometimes it relates to the speed of the wind, as in the faster the wind the lower the flyability of the balloon.
The flowability of the piece was wrecked after the writer interjected a number of absurd references that made no sense and added nothing of value to the article.