Caravan Undifferentiated
Air Traffic Control Fully Certified
Other / Unknown
ATC Issue All Types
Flight Crew Took Evasive Action
Procedure
After the national weather service advised they were going to release the weather balloon in the next couple of minutes; I advised all aircraft in a blank transmission about this. Minutes later; I cleared a Caravan for take off Runway 10 when seconds later I observed the weather balloon midfield of Runway 10 appearing to be in close proximity to the runway. Since it was hard to determine the position of the weather balloon; I advised the pilot of the situation and approved a deviation if the pilot needed. Seconds later I observed the Caravan making a sharp turn to the left appearing to try to avoid the weather balloon and after the maneuver; resumed course without incident. Although for many years I never had an incident involving approving the release of the weather balloon; this was the first time I have became concerned with this procedure. The conditions placed the balloon almost over the runway. Changes in the procedures for approving balloon releases should be considered. I recommend that the balloon is released immediately as the approval is granted.
A SJU Controller observed a departure vs. a weather balloon conflict. He now questions the procedures for releasing the balloons.