The justification for flying halfway around the world to go testing in Sepang is simple: While Europe is still dealing with the after-effects of winter, plagued by cold, wind and rain, the temperature at Sepang is reliably warm, and despite the usual tropical storms in the afternoon, the chance of having a dry track to test on is very good.
Of course, it doesn't always work out that way. Sometimes, the rain falls much earlier, and the intensity of tropical thunderstorms makes it unsafe to go out on the track until the storm has passed, and the amount of rain that falls leaves a lot of water on the track.
Such was the case on the first day of the second MotoGP test at Sepang. A tropical storm moved in shortly after lunchtime, and the heavy rain left wet patches on the track for most of the afternoon. All the air miles gathered by riders and team staff flying in from around the world were mostly in vain, as they sat in their garages waiting for the rain to pass.